Colliers International Group Inc.

Colliers began in Australia in 1976 after Glynn Lynch & McHarg and Jones Lang Wootten & Sons merged under the Colliers name. In 1978, Colliers merged with Hong Kong–based Tony Petty & Associates.

In 1984, Colliers merged with Macaulay Nicolls. The following year, the company merged with American Realty Services Group. In 1992, the company merged with Jardines, a British firm.

In 2004, FirstService Corporation bought a controlling interest in Colliers Macaulay Nicolls, Colliers' largest member. After gaining controlling interest, Macaulay Nicolls became First Service REA.

In 2006, FirstService purchased a majority stake in PGP Valuation and merged with the appraisal arm of Colliers Macaulay Nicolls. In 2007, FirstService acquired an 80 percent stake in PKF Hotel and Hospitality Consulting and a 60 percent stake in MHPM Project Managers.

In September 2008, FirstService purchased a 65 percent stake in GVA Williams. In 2009, FirstService gained control of Colliers after acquiring large shareholders. In October, Colliers invested in Colliers CRE, a London-based real estate services company.

In January 2010, the merger of Colliers and FirstService was announced. Following the merger in April 2010, Dylan Taylor became president and CEO of Colliers International's US operations. Also in April, Colliers invested in Colliers Bennett & Kahnweiler and West Shell Commercial in Cincinnati, Ohio. The following month, Adena Commercial, a real estate firm in Columbus, Ohio, and Grubb & Ellis Paramount Commerce in Grand Rapids, Michigan, began working with Colliers International. In June 2010, Colliers partnered with Sutton & Edwards, a real estate firm in Long Island, New York.

In July 2014, PKF Consulting was sold to CBRE Group. In June 2015, Colliers International and FirstService Corporation separated into two independent, publicly traded companies – Colliers International Group Inc. and FirstService Corporation.

In September 2016, Stephen Harper, Canada's former Conservative Prime Minister, was appointed to the company's board.

In October 2017, Colliers acquired Serten Advisors, LLC; a tenant representation firm headquartered in the Washington, D.C., area.

In May 2018, Colliers acquired a majority 75% stake in Harrison Street for $550 million.

In September 2019, Colliers acquired Synergy Property Development Services, an Indian real estate company.

In December 2019, Colliers acquired certain divisions of Doughtery Financial based in Minneapolis.

In July 2020, Colliers acquired Maser Consulting P.A., a multi-discipline engineering design services firm based in New Jersey.

In July 2025, Colliers restructured its entire investment management business to be under the Harrison Street brand. These would include its companies: Basalt Infrastructure Partners, Versus Capital, Rockwood Capital, and Colliers Global Investor. The new unit would be named Harrison Street Asset Management.