Founded in 1993 as Mainframe Entertainment Inc. by Christopher Brough, Ian Pearson, Phil Mitchell, Gavin Blair and John Grace, the company established itself as a leading contributor to the introduction of computer-generated imagery (CGI) live action in animation, film and television.

Due to the cost of shipping equipment back home, advantageous tax credits and proximity to Los Angeles, the company set up shop in Vancouver, Canada.

[7] Mainframe opened its American division in Los Angeles on April 17, 1998, to be led by Dan DiDio and oversee content development, production and local distribution.

After having earlier produced two ReBoot themed rides for the company, the IMAX Corporation made a $16 million investment in the company in 1999, which gave IMAX roughly 30% ownership of Mainframe, included the creation of a new joint venture meant to facilitate the creation of animated films based on Gulliver's Travels and Pied Piper, with a third project titled Pandora’s Box.

[12] Buoyed by Heavy Gear, Action Man and their first direct-to-video film, Casper's Haunted Christmas, Mainframe posted another profit of $2.4 million for fiscal 2001.

While a number of projects were announced they ultimately did not see fruition, including a pre-school oriented ReBoot spinoff called Binomes as well as Mainframe's first live-action production, an adaptation of Harriet the Spy.

[27][28] This branch of the company worked on a number of projects, including cut-scenes for Prototype, 50 Cent: Blood on the Sand and Ghostbusters: The Video Game, as well as the 2006 MTV Movie Awards.

[29] Finding itself under new ownership, IDT sold its 62% stake in Mainframe to Vancouver-based post-production firm Rainmaker Income Fund on July 20, 2006, for $13.8 million.

[33] Later that year, Rainmaker sold its visual effects and post production divisions to Deluxe Entertainment Services Group, leaving only the animation business.

On October 7 that same year, Rainmaker launched a television production division and revived the "Mainframe Entertainment" brand for its title, starting with a CG-animated incarnation of Bob the Builder.

[48] On June 24, 2021, the company confirmed that it would develop a 2D-animation pipeline in support of its first production in the medium, an animated series inspired by YouTube personality Guava Juice.

[49] The following August, Mainframe announced that it would open a virtual studio in Toronto in the east of the country, building upon its earlier remote work experience.