UNITEDSTATES

SECURITIESAND EXCHANGE COMMISSION

Washington,D.C. 20549

FORM6-K

REPORTOF FOREIGN PRIVATE ISSUER

PURSUANTTO RULE 13a-16 OR 15d-16 UNDER

THESECURITIES EXCHANGE ACT OF 1934

Forthe month of: August 2025

Commissionfile number 001-36897

FIRSTSERVICECORPORATION

(Translationof registrant’s name into English)

1255Bay Street, Suite 600

Toronto,Ontario, Canada

M5R2A9

(Addressof principal executive office)

Indicateby check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form20-F ☐                       Form 40-F ☒

SIGNATURE

Pursuantto the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf bythe undersigned, hereunto duly authorized.

EXHIBITINDEX

Exhibit 99.1

FIRSTSERVICE CORPORATION

INTERIM CONSOLIDATED FINANCIAL STATEMENTS

SecondQuarter

June30, 2025

NOTICE OF NO AUDITOR REVIEW OF INTERIM FINANCIALSTATEMENTS

The unaudited interim consolidated financial statementsof FirstService Corporation, which include the unaudited interim consolidated balance sheet as at June 30, 2025 and the unaudited interimconsolidated statements of earnings, comprehensive earnings, shareholders’ equity and cash flows for the three and six month periodsthen ended are the responsibility of management. The financial statements have been prepared in accordance with accounting principlesgenerally accepted in the United States of America and, where appropriate, reflect estimates based on the best judgment of management.

These unaudited interim consolidated financial statementshave not been audited or reviewed on behalf of the shareholders by the independent external auditors of the Company, PricewaterhouseCoopersLLP.

August 1, 2025

The accompanying notes are an integral part of these financialstatements.

The accompanying notes are an integral part of these financial statements.

The accompanying notes are an integral part of these financial statements.

FIRSTSERVICE CORPORATION

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY

(Unaudited)

(in thousands of US dollars, except share information)

FIRSTSERVICE CORPORATION

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (continued)

(Unaudited)

(in thousands of US dollars, except share information)

FIRSTSERVICE CORPORATION

CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited)

(in thousands of US dollars) - in accordance with accounting principlesgenerally accepted in the United States of America

The accompanyingnotes are an integral part of these financial statements.

FIRSTSERVICE CORPORATION

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

June 30, 2025

(Unaudited)

(in thousands of US dollars, except per share amounts)

1.       DESCRIPTIONOF THE BUSINESS – FirstService Corporation (the “Company”) is a North American provider of residential property managementand other essential property services to residential and commercial customers. The Company’s operations are conducted in two segments:FirstService Residential and FirstService Brands. The segments are grouped with reference to the nature of services provided and the typesof clients that use those services.

FirstService Residential is a full-service propertymanager and in many markets provides a full range of ancillary services primarily in the following areas: on-site staffing, includingbuilding engineering and maintenance, full-service amenity management, security, concierge and front desk personnel; proprietary bankingand insurance products; and energy conservation and management solutions.

FirstService Brands provides a range of essentialproperty services to residential and commercial customers in North America through company-owned locations and franchise networks. Theprincipal brands in this division include First Onsite Property Restoration, Paul Davis Restoration, Roofing Corp of America, CenturyFire Protection, California Closets, CertaPro Painters, Floor Coverings International, and Pillar to Post Home Inspectors.

2.       SUMMARYOF SIGNIFICANT ACCOUNTING POLICIES – These condensed consolidated financial statements have been prepared by the Company in accordancewith the disclosure requirements for the presentation of interim financial information pursuant to applicable Canadian securities law.Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with generally acceptedaccounting principles (“GAAP”) in the United States of America have been condensed or omitted in accordance with such disclosurerequirements, although the Company believes that the disclosures are adequate to make the information not misleading. These interim financialstatements should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2024.There are no developments since the Company’s disclosures in its December 31, 2024 audited consolidated financial statements relatingto new standards issued but not finalized.

These interim financial statements follow the sameaccounting policies as the most recent audited consolidated financial statements. In the opinion of management, the unaudited condensedconsolidated financial statements contain all adjustments necessary for a fair statement of the financial position of the Company as atJune 30, 2025 and the results of operations and its cash flows for the three and six month periods ended June 30, 2025 and 2024.All such adjustments are of a normal recurring nature. The condensed balance sheet at December 31, 2024 was derived from audited annualfinancial statements but does not contain all of the footnote disclosures from the annual financial statements. The results of operationsfor the three and six month periods ended June 30, 2025 are not necessarily indicative of the results to be expected for the yearending December 31, 2025.

3.       REVENUERECOGNITION – Disaggregated revenues are as follows:

The Company disaggregates revenue by segment. Withinthe FirstService Brands segment, the Company further disaggregates its company-owned operations revenue; these businesses primarily recognizerevenue over time as they perform because of continuous transfer of control to the customer. As such, revenue is recognized based on theextent of progress towards completion of the performance obligation. The Company generally uses the percentage of completion method.

We believe this disaggregation best depicts how thenature, amount, timing and uncertainty of the Company’s revenue and cash flows are affected by economic factors.

The Company’s backlog represents remaining performanceobligations and is defined as contracted work yet to be performed. As at June 30, 2025, the aggregate amount of backlog was $1,111,356(December 31, 2024 - $924,803). The Company expects to recognize revenue on the majority of the remaining backlog over the next 12 months.

The majority of current unearned revenues as at June30, 2025 are expected to be recognized into income within 12 months of the balance sheet date.

4.       ACQUISITIONS– During the six months ended June 30, 2025, the Company completed six acquisitions, two in the FirstService Residential segmentand four in the FirstService Brands segment. In the FirstService Residential segment, the Company acquired an amenity management firm,headquartered in Ithaca, New York, as well as a property management company located in Edmonton, Alberta. Within the FirstService Brandssegment, the Company acquired two independent roofing businesses located in Alberta, Canada, and San Diego, California, respectively.In addition, the Company acquired a Paul Davis franchisee operating in Pennsylvania, as well as an independent fire protection businessheadquartered in Salt Lake City, Utah. The acquisition date fair value of consideration transferred was as follows: cash of $51,916 (netof cash acquired of $7,534), and contingent consideration of $5,683.

During the six months ended June 30, 2024, the Companycompleted six acquisitions for cash consideration of $154,649 (net of cash acquired of $24,504), and contingent consideration of $42,454.

Acquisition-related items included both transactioncosts and contingent acquisition consideration fair value adjustments. Acquisition-related transaction costs for the six months totaled$6,488 (2024 - $3,256). Also included in acquisition-related items was an increase of $13,407 related to contingent acquisition considerationfair value adjustments (2024 - $650).

The purchase price allocations for certain transactionscompleted in the last six months are not yet complete, pending final determination of the fair value of assets acquired. These acquisitionswere accounted for by the purchase price method of accounting for business combinations and accordingly, the consolidated statements ofearnings do not include any revenues or expenses related to these acquisitions prior to their respective closing dates. There have beenno material changes to the estimated purchase price allocations determined at the time of acquisition during the six months ended June30, 2025.

Except for where arrangements represent compensationfor the benefit of the Company, contingent consideration is recorded at fair value each reporting period. The fair value recorded on theconsolidated balance sheet as at June 30, 2025 was $85,641 (see note 9). The estimated range of outcomes (undiscounted) for these contingentconsideration arrangements is $73,720 to a maximum of $86,729. The contingencies will expire during the period extending to January 2028.During the six months ended June 30, 2025, $900 was paid with reference to such contingent consideration (2024 - $25,513).

5.       LEASES– The Company has operating leases for corporate offices, copiers, and certain equipment. Its leases have remaining lease termsof 1 year to 14 years, some of which may include options to extend the leases for up to 15 years, and some of which may include optionsto terminate the leases within 1 year. The Company evaluates renewal terms on a lease by lease basis to determine if the renewal is reasonablycertain. The amount of operating lease expense recorded in the statement of earnings for the six months ended June 30, 2025 was $36,407(2024 - $30,922).

Other information related to leases was as follows (in thousands):

6.       INVENTORIES - Inventories are comprised of the following:

7.       INCOMETAX – The provision for income tax for the six months ended June 30, 2025 reflected an effective tax rate of 30% (2024 - 29%).

8.       LONG-TERMDEBT – In February 2025, the Company entered into a third amended and restated credit agreement providing for a $1,750,000 revolvingcredit facility on an unsecured basis. The maturity date of the revolving credit facility is February 2030. The revolving credit facilitybears interest at 0.20% to 2.50% over floating reference rates, depending on certain leverage ratios.

In September 2022 (and as amended in April 2024 asnoted below), the Company entered into two revolving, uncommitted financing facilities for potential future private placement issuancesof senior unsecured notes (the “Notes”) aggregating $550,000 with its existing lenders, NYL Investors LLC (“New YorkLife”) of up to $250,000 and PGIM Private Capital (“Prudential”), of up to $300,000, in each case, net of any existingnotes held by them. The facility with Prudential has a term ending September 29, 2025, and the facility with New York Life has a termending April 3, 2027. As part of the closing of the New York Life facility, the Company issued, on a private placement basis to New YorkLife, $60,000 of 4.53% Notes, which are due in full on September 29, 2032, with interest payable semi-annually. In April 2024, the facilitywith New York Life was amended to increase the potential financing capacity by $100,000, to the current $250,000, and to extend the termof the New York Life facility from September 29, 2025 to the current April 3, 2027. The Company has the ability to issue incremental Notetranches under the facilities, subject to acceptance by New York Life or Prudential, with varying maturities as determined by the Company,and with coupon pricing determined at the time of each Note issuance.

In January 2024, the Company issued, on a privateplacement basis to New York Life, $50,000 of 5.48% Notes, which are due in full on January 30, 2029, as well as $25,000 of 5.60% Notes,which are due in full on January 30, 2031, both with interest payable semi-annually. Also in January 2024, the Company issued, on a privateplacement basis to Prudential, $50,000 of 5.64% Notes, which are due in full on January 30, 2031, with interest payable semi-annually.

The indebtedness under the Credit Agreement and theNotes rank equally in terms of seniority. The Company is prohibited under the Credit Agreement from undertaking certain acquisitions anddispositions, and incurring certain indebtedness and encumbrances, without prior approval of the lenders under the Credit Agreement.

9.       FAIR VALUEMEASUREMENTS – The following table provides the financial assets and liabilities carried at fair value measured on a recurring basisas of June 30, 2025:

The fair value of the interest rate swap liabilitywas calculated through discounting future expected cash flows using the appropriate prevailing interest rate swap curve adjusted for creditrisk. The inputs to the measurement of the fair value of contingent consideration related to acquisitions are Level 3 inputs using a discountedcash flow model; significant model inputs were expected future operating cash flows (determined with reference to each specific acquiredbusiness) and discount rates (which range from 8% to 10%). The range of discount rates is attributable to the level of risk related toeconomic growth factors combined with the length of the contingent payment periods; and the dispersion was driven by unique characteristicsof the businesses acquired and the respective terms for these contingent payments. Within the range of discount rates, there is a datapoint concentration at 9%. A 2% increase in the weighted average discount rate would not have a significant impact on the fair value ofthe contingent consideration balance.

Changes in the fair value of the contingent considerationliability are comprised of the following:

The carrying amounts for cash and cash equivalents,accounts receivable, accounts payable and accrued liabilities approximate fair values due to the short maturity of these instruments,unless otherwise indicated. The inputs to the measurement of the fair value of long term debt are Level 2 inputs. The fair value measurementswere made using a net present value approach; significant model inputs were expected future cash outflows and discount rates (which rangefrom 4.5% to 5.0%). The following are estimates of the fair values for other financial instruments:

10.       REDEEMABLENON-CONTROLLING INTERESTS – The minority equity positions in the Company’s subsidiaries are referred to as redeemable non-controllinginterests (“RNCI”). The RNCI are considered to be redeemable securities. Accordingly, the RNCI is recorded at the greaterof: (i) the redemption amount; or (ii) the amount initially recorded as RNCI at the date of inception of the minority equity position.This amount is recorded in the “mezzanine” section of the balance sheet, outside of shareholders’ equity. Changes inthe RNCI amount are recognized immediately as they occur. The following table provides a reconciliation of the beginning and ending RNCIamounts:

The Company has shareholders’ agreements inplace at each of its non-wholly owned subsidiaries. These agreements allow the Company to “call” the non-controlling interestat a price determined with the use of a formula price, which is usually equal to a fixed multiple of average annual net earnings beforeextraordinary items, income taxes, interest, depreciation, and amortization, less debt. The agreements also have redemption features whichallow the owners of the RNCI to “put” their equity to the Company at the same price subject to certain limitations. The formulaprice is referred to as the redemption amount and may be paid in cash or in the Company’s Common Shares. The redemption amount asof June 30, 2025 was $391,148. The redemption amount is lower than that recorded on the balance sheet as the formula prices of certainRNCI are lower than the amount initially recorded at the inception of the minority equity position. If all put or call options were settledwith Common Shares as at June 30, 2025, approximately 2,200,000 such shares would be issued; this would be accretive to net earnings pershare.

Increases or decreases to the formula price of theunderlying shares are recognized in the statement of earnings as the NCI redemption increment.

11.       NET EARNINGSPER COMMON SHARE – The following table reconciles the basic and diluted common shares outstanding:

12.       STOCK-BASEDCOMPENSATION

Company stock option plan

The Company has a stock option plan for certain officersand key full-time employees of the Company and its subsidiaries. The stock option plan came into existence on June 1, 2015. Options aregranted at the market price for the underlying shares on the date of grant. Each option vests over a three-to-five-year term, expiresfive to six years from the date granted and allows for the purchase of one Common Share. All Common Shares issued are new shares. As atJune 30, 2025, there were 763,240 options available for future grants.

Grants under the Company’s stock option planare equity-classified awards. There were no stock options granted during the three months ended June 30, 2025 (2024 – nil). TheCompany estimates the probability of achievement of performance conditions at each reporting period and reflects the estimates in thenumber of options expected to vest with any changes recognized through stock-based compensation expense. Stock option activity for thesix months ended June 30, 2025 was as follows:

The amount of compensation expense recorded in thestatement of earnings for the six months ended June 30, 2025 was $14,155 (2024 - $13,927). As of June 30, 2025, there was $45,254 of unrecognizedcompensation cost related to non-vested awards which is expected to be recognized over the next 5 years. During the six month period endedJune 30, 2025, the fair value of options vested was $18,361 (2024 - $17,078).

13.       CONTINGENCIES– In the normal course of operations, the Company is subject to routine claims and litigation incidental to its business. Litigationcurrently pending or threatened against the Company includes disputes with former employees and commercial liability claims related toservices provided by the Company. The Company believes resolution of such proceedings, combined with amounts set aside, will not havea material impact on the Company’s financial condition or the results of operations.

14.       SEGMENTEDINFORMATION – The Company has two reportable operating segments as determined by the chief operating decision maker (CODM), whois the Chief Executive Officer of the Company. The segments are grouped with reference to the nature of services provided and the typesof clients that use those services. The CODM assesses each segment’s performance based on operating earnings. Specifically, theCODM uses operating earnings to monitor results against expectations for each reportable segment. FirstService Residential provides propertymanagement and related property services to residential communities in North America. FirstService Brands provides Company-owned and franchisedproperty services to customers in North America. Corporate includes the costs of operating the Company’s corporate head office.

FIRSTSERVICE CORPORATION

MANAGEMENT’S DISCUSSION AND ANALYSIS

For the Six Month Period Ended June 30, 2025

(in US dollars)

August 1, 2025

The following Management’s Discussion and Analysis (“MD&A”)should be read together with the unaudited interim condensed consolidated financial statements of FirstService Corporation (the “Company”or “FirstService”) for the three and six month periods ended June 30, 2025 and the Company’s audited consolidatedfinancial statements, and MD&A, for the year ended December 31, 2024. The interim consolidated financial statements have beenprepared in accordance with generally accepted accounting principles in the United States (“GAAP”). All financial informationherein is presented in United States dollars.

The Company has prepared this MD&A with reference to National Instrument51-102 – Continuous Disclosure Obligations of the Canadian Securities Administrators (the "CSA"). Under the U.S./CanadaMultijurisdictional Disclosure System, the Company is permitted to prepare this MD&A in accordance with the disclosure requirementsof Canada, which requirements are different from those of the United States. This MD&A provides information for the three and sixmonth periods ended June 30, 2025 and up to and including August 1, 2025.

Additional information about the Company, including the Company’sAnnual Information Form, which is included in FirstService’s Annual Report on Form 40-F, can be found on SEDAR+ at www.sedarplus.caand on the US Securities and Exchange Commission website at www.sec.gov.

Results of operations - three months ended June 30, 2025

Consolidated revenues for our second quarter were $1.42 billion, 9%higher than the comparable prior year quarter.

Consolidated operating earnings for the second quarter were $97.3 million,compared to $83.9 million in the prior year quarter. The operating earnings margin was 6.9% versus 6.5% in the prior year quarter. AdjustedEBITDA (see “Reconciliation of non-GAAP measures” below) for the second quarter was $157.1 million, up from $132.5 millionreported in the prior year quarter. Our Adjusted EBITDA margin was 11.1% of revenues versus 10.2% of revenues in the prior year quarter.

Depreciation and amortization expense totalled $45.6 million, relativeto $39.2 million in the prior year, with the increase primarily related to recently acquired operations in both our FirstService Residentialand FirstService Brands segments.

Acquisition-related items for the second quarter were $7.7 million, upfrom $2.3 million in the prior period. The increase was mainly due to fair value adjustments to contingent upside earn-out structuresin the FirstService Brands segment.

The consolidated income tax rate for the quarter was 30%, compared to 29%in the prior year quarter. The effective tax rate for the full year is expected to be approximately 30%.

On July 4, 2025, the One Big Beautiful Bill Act was signed into law inthe U.S., which contains a broad range of tax reform provisions affecting businesses. We are evaluating the full effects of the legislationon our estimated annual effective tax rate and cash tax position, but we expect that the legislation will likely not have a material impacton our financial statements. As the legislation was signed into law after the close of our second quarter, the impacts are not includedin our operating results for the six months ended June 30, 2025.

Net earnings for the quarter were $55.4 million, versus $44.9 millionin the prior year quarter, with the increase attributable to higher profitability in both segments.

The RNCI redemption increment for the second quarter was $5.9 million,versus $7.2 million in the prior period, and was attributable to changes in the trailing two-year average of earnings of non-wholly ownedsubsidiaries.

The FirstService Residential segment reportedrevenues of $593.0 million for the second quarter, up 6% versus the prior year, including organic growth of 3% (see “Reconciliationof non-GAAP measures” below). Adjusted EBITDA was $65.5 million, or 11.0% of revenues, versus $59.1 million, or 10.6% of revenues,in the prior year quarter. Operating earnings were $51.6 million, or 8.7% of revenues, versus $49.1 million, or 8.8% of revenues,for the second quarter of last year. The Adjusted EBITDA margin improvement reflected ongoing efficiencies in our property managementclient service delivery model. The Operating Earnings margin remained in-line with the prior year primarily due to increased depreciationin the segment.

Second quarter revenues at our FirstServiceBrands segment were $822.7 million, up 11% relative to the prior year quarter. On an organic basis, division revenues were up 1%,with double-digit growth at Century Fire Protection, offsetting modestly lower quarter-over-quarter results in our Roofing Corp of Americaoperations. Recent tuck-under acquisitions across the segment also contributed to the top-line increase. Adjusted EBITDA for the quarterwas $95.2 million, or 11.6% of revenues, versus $77.6 million, or 10.5% of revenues, in the prior year quarter. Operating earningsfor the second quarter were $56.5 million, or 6.9% of revenues, versus $46.3 million, or 6.3% of revenues, in the prior yearquarter. The increase in operating margins was attributable to continued operating process improvements at our restoration and home servicebrands.

Corporate costs (see definitions and reconciliationsbelow), as presented in Adjusted EBITDA, were $3.6 million, relative to $4.2 million in the prior year quarter. Corporate costs for thecurrent quarter were $10.9 million in the quarter versus $11.5 million in the prior year quarter.

Results of operations - six months ended June 30, 2025

Revenues for the six months ended June 30,2025 were $2.67 billion, 9% higher than the comparable prior year period.

Operating earnings for the period were $136.5 million,versus $122.0 million in the prior year. Our operating earnings margin was 5.1% of revenues versus 5.0% of revenues in the prioryear period. Year-to-date Adjusted EBITDA (see “Reconciliation of non-GAAP measures” below) was $260.4 million, up from$215.9 million reported in the comparable prior year period. Our Adjusted EBITDA margin was 9.8% of revenues versus 8.8% of revenuesin the prior year.

Depreciation and amortization expense totalled$89.8 million, relative to $76.0 million in the prior year, with the increase primarily related to recently acquired operations in bothour FirstService Residential and FirstService Brands segments.

Acquisition-related items were $19.9 million,up from $3.9 million in the prior period. The increase was primarily due to fair value adjustments to contingent upside earn-out structuresin the FirstService Brands segment.

Our consolidated income tax rate for thesix-month period was 30%, versus 29% in the prior year-to-date period.

Net earnings for the six-month period were$69.5 million, up from $59.8 million in the prior year period, and was attributable to higher profitability in both segments.

The RNCI redemption increment for the periodwas $15.9 million, versus $14.2 million in the prior period, and was attributable to changes in the trailing two-year averageof earnings of non-wholly owned subsidiaries.

Our FirstService Residential segment reportedrevenues of $1.12 billion for the six-month period, up 6% over the prior year period, including 3% organic growth. Adjusted EBITDA was$107.1 million, or 9.6% of revenues, up from $94.7 million, or 9.0% of revenues, in the prior year period. Operating earnings were$80.9 million, or 7.2% of revenues, for the six-month period, relative to $75.8 million, or 7.2% of revenues, in the prior yearperiod. The Adjusted EBITDA margin improvement was due to realized operating efficiencies in our property management client service deliverymodel. The Operating Earnings margin remained flat versus the prior year period mainly due to increased depreciation in the segment.

Year-to-date revenues at FirstService Brands were $1.55 billion, anincrease of 10% relative to the prior year period, all from acquisition growth. Revenue growth was driven by double-digit organic growthat Century Fire Protection, offset by reduced activity-levels at our Roofing Corp of America operation. Adjusted EBITDA for the periodwas $163.0 million, or 10.5% of revenues, up from $133.0 million, or 9.5% of revenues, in the prior year period. Operating earningswere $81.0 million, or 5.2% of revenues, versus $73.1 million, or 5.2% of revenues, in the prior year. The Adjusted EBITDA marginexpansion was largely driven by continued improvements in our operating processes and cost structure at our restoration and home servicesbrands. The Operating Earnings margin remained in-line with the prior year due to increased contingent upside earn-out adjustments tiedto recently completed acquisitions.

Corporate costs (see definitions and reconciliations below), as presentedin Adjusted EBITDA, for the six-month period were $9.7 million versus $11.9 million in the prior year period. Corporate costs were $25.3million, compared to $26.9 million in the prior year, with the decrease due to the impact of foreign exchange.

Summary of quarterly results

The following table sets forth FirstService’s quarterly consolidatedresults of operations data for each of the ten most recent quarters. The information in the table below has been derived from FirstService’sinterim consolidated financial statements (except for other data which is non-GAAP), that, in management’s opinion, have been preparedon a consistent basis and include all adjustments necessary for a fair presentation of information. The information below is not necessarilyindicative of results for any future quarter.