The 25-year-old quarterback signed with the Hamilton Tiger-Cats on Tuesday, a day after being released by the Toronto Argonauts. Collaros' deal is through the 2016 season.
"Zach is a very talented quarterback with a great future in front of him," Hamilton coach and GM Kent Austin said in a statement. "He's a dedicated, proven winner and a natural leader with tremendous character.
"We are very excited that he has chosen to join our football team."
Hamilton and the Winnipeg Blue Bombers were the two leading suitors for Collaros, who posted a 5-2 record last season as a starter subbing for the injured Ricky Ray.
The six-foot-two, 216-pound Collaros completed 190-of-287 passes (66.2 per cent) for 2,316 yards with 14 TDs and six interceptions. He also ran 59 times for 246 yards and five touchdowns and was scheduled to become a free agent Feb. 15
"I'm very excited to join the Tiger-Cats," Collaros said. "This team has all the pieces in place for success now and in the future.
"I can't wait to work with the players, coaches and staff in Hamilton and play in front of an outstanding fan base at Tim Hortons Field."
Collaros, entering his third CFL season, played collegiately at Cincinnati. He completed 485-of-783 passes for 6,272 yards and 51 touchdowns. He ran 268 times for 1,240 yards and scored 16 TDs.
The signing of Collaros ends veteran Henry Burris's time in Hamilton as he was released Thursday.
Burris guided Hamilton to a Grey Cup berth last season and was slated to become a free agent next month.
Burris is expected to garner a lot of attention from the Bombers, who used three different starters last season in posting a league-worst 3-15 record.
Collaros will join a Hamilton squad with youngsters Dan LeFevour and Jeremiah Massoli along with former NFLers Brian Brohm and Stephen McGee under contract.