CGI Inc. (Consultants to Government and Industry Incorporated) is a Canadian multinational information technology consulting and Software Development company headquartered in Montreal, Quebec, Canada. CGI went public in 1986 with a primary listing on the Toronto Stock Exchange. CGI is also a constituent of the S&P/TSX 60 and has a secondary listing on the New York Stock Exchange.

As of 2024, CGI is based in 40+ countries with around 400 offices worldwide with 95,000+ employees. CGI mainly works in application services, business consulting, business process Management, IT infrastructure services, IT outsourcing services, and systems integration services.

CGI Inc. was founded as an IT consulting company on June 15, 1976, in Quebec City, Québec, by Serge Godin. Within several months he was joined by co-founder André Imbeau from Quebec City. They initially ran the business from Godin's basement with a single phone. Starting with one client, as the company grew in size the co-founders moved to Montreal, and by the end of their first year they had generated $138,000 in revenue. While CGI stands for "Conseillers en gestion et informatique" in French (which translates to "consultants in management and information technology"), the official English meaning would later become "Consultants to Government and Industry." In later years the company began to go to market as simply CGI.

Throughout the 1970s, CGI focused on the information technology (IT) services market. Later in the 1970s, CGI branched into IT outsourcing. CGI's annual revenue in 1986 was $25 million, and the same year CGI went public with an initial public offering (IPO).

CGI earned ISO 9001 certification for their "project management framework" in 1994, and in doing so became the first IT consulting firm in North America to comply with the ISO quality standard. In 1995, CGI entered into a commercial alliance with the large telecommunications company Bell Canada, with Bell Canada purchasing CGI shares then valued at $18.4 million. By the end of 1996, CGI's annual revenue was $122 million. In 1997, CGI acquired the company CDSL Holdings Limited (CDSL). After the acquisition, CGI's employees in both Canada and internationally numbered 2,500. In 1998 CGI acquired the Canadian company Bell Sygma, a Bell Canada subsidiary, which almost doubled CGI's size.

CGI acquired IMRGlobal in 2001 for $438 million, which added "global delivery options" for CGI. In 2003, the Canadian tech company Cognicase was bought out by CGI for US$221 million, and at the end of 2003 CGI had annual sales of $1.85 billion. In 2004, CGI purchased the majority of American Management Systems (AMS) for $858 million. As of late 2004, CGI was the world's eighth largest independent provider of information technology services.

CGI co-founder Serge Godin stepped aside as CEO in 2006, taking the new position of executive chairman of the board and appointing as new CEO Michael Roach. Annual revenue at CGI was $3.5 billion by the fiscal end of 2006. That same year, CGI became one of four primary Recovery Audit Contractors in the US, with responsibilities to audit region B. At the end of 2007, CGI had a backlog worth $12.04 billion and an annual revenue of $3.7 billion, employing around 26,500 people.

In 2010, CGI acquired Stanley, Inc. for an enterprise value of approximately $1.07 billion. The deal came close to doubling CGI's presence in the United States and expanded CGI into defense and intelligence contracts. In 2010, CGI was included in the Forbes Global 2000 ranking of the 2,000 largest public companies in the world. As of 2011, there were 31,000 CGI employees in 125 offices worldwide and 89% of professionals at CGI also owned company shares.