Porter and Bruce inked three-year deals while Parker signed a two-year contract.
"We welcome Arland, Byron and Quinton to the Alouettes. We have added three solid professionals to our organization today," Alouettes general manager Jim Popp said in a statement.
The Alouettes snapped up all three players after they were released by their former teams last week. Bruce and Parker are former CFL all-stars who were released on Friday by B.C., a day after the Lions signed quarterback Travis Lulay to a new deal.
Porter, who backed up Henry Burris in Hamilton last season, was released last Tuesday.
Parker is a nine-year CFL veteran, and has 236 career defensive tackles and 29 interceptions with B.C., Toronto and Edmonton since 2005.
Parker's most effective season came with the Argonauts in 2011, when he recorded a career-best 50 defensive tackles.
He was named a CFL all-star in 2006, 2007 and 2011. He holds the league record for career interceptions returned for touchdowns (nine) and interception return yards in a single season (348).
"Byron comes in as one of the top DBs in the CFL over the last decade," Popp said. "We welcome his leadership and ability to make big plays."
Bruce has spent 11 seasons in the CFL with Winnipeg, Toronto, Hamilton and B.C., and has recorded more than 10,000 receiving yards and 89 touchdowns.
He caught 43 passes for 603 yards and five touchdowns last year. He missed the final five games of the regular season with a concussion before returning for the Western final, which B.C. lost to Calgary.
"Arland offers us a solid playmaker and legitimate game changer," said Popp. "He is one of those players that makes the other team a little nervous when he is on the field."
Bruce eclipsed the 1,000-yard receiving mark six times in his career. He is a two-time Grey Cup winner (2004 and 2011) and was selected as a CFL all-star in 2006, 2009, and 2010.
Porter spent some time starting as Hamilton's starting quarterback since joining the team in 2008, but was used sparingly last season.
During his time in Hamilton, Porter completed 358 of 562 passes (63.7 per cent) for 4,095 yards with 21 touchdowns and 18 interceptions.
"Quinton has been on my radar screen for sometime," Popp said. "We feel his potential can reach great heights and we look forward in getting him into the Alouettes' system."