Sinopoli was drafted 29th overall in the fourth round of the 2011 CFL Draft by the Calgary Stampeders. He was later signed to a contract with the Stampeders on May 20, 2011. He dressed in all 18 regular season games for the 2011 season as the third-string quarterback as well as dressing in the West Semi-Final. Sinopoli served as the team's holder for placekicks in all of their games as well. Prior to the start of the 2012 regular season, Sinopoli was released by the Stampeders. Following an injury to Calgary's starting quarterback Drew Tate, Sinopoli was re-signed by the Stampeders on July 9, 2012. Thereafter, Sinopoli dressed for ten games as the third-string quarterback before Tate went back on the active roster. Following another injury to Tate, Sinopoli dressed in the West Final and 100th Grey Cup. Due to the entrenched quarterbacks on the depth chart, Sinopoli was moved to wide receiver for the 2013 CFL season, with his first career reception coming against the Montreal Alouettes. Sinopoli recorded his first CFL touchdown on a 26-yard run in a 10–7 victory over the Hamilton Tiger-Cats on July 18, 2014. He finished the 2013 season with 34 receptions and 417 receiving yards in 14 regular season games played. In 2014, he recorded his first receiving touchdown in a game against the Toronto Argonauts on September 13, 2014. He broke his collarbone while catching a touchdown pass on October 17, 2014 and sat out the rest of the season. While he didn't play in the game, Sinopoli earned his first Grey Cup championship following the Stampeders' victory in the 102nd Grey Cup game.
Ottawa Redblacks
On February 10, 2015, Sinopoli signed a free agent contract with the Ottawa Redblacks. He had a break-out season with the Ottawa Redblacks; playing in all 18 regular season games and becoming one of four Ottawa receivers with 1000-yard receiving seasons. Sinopoli finished the regular season with 86 receptions, for 1,035 yards with three touchdowns. His successful season was rewarded when he was named the CFL's Most Outstanding Canadian. In 2016, Sinopoli surpassed his 2015 performance by finishing the regular season with 90 receptions, for 1036 with four touchdowns. He would also go on to win the Dick Suderman Trophy as the Most Valuable Canadian player at the 104th Grey Cup after compiling six receptions for 94 yards and one touchdown in the Redblacks' upset victory over the Calgary Stampeders. In the Redblacks' second to last regular season game of the 2017 season, Sinopoli injured his shoulder. Following the team's bye week it was announced that he would miss the remainder of the season with a broken bone in his shoulder that would require surgery. At the time of his injury, Sinopoli was seventh in the league in receiving yards with 1,009. Immediately following the 2017 season, Sinopoli signed a new two-year extension. He played in 17 games in 2018, resting for the last game of the regular season, but still managed to post a career-high 116 receptions for 1376 receiving yards and four touchdowns. He set an all-time CFL record for receptions in a season by a Canadian player as well as setting the all-time Ottawa professional football record for most receptions in a season. 2019 was a down year for Sinopoli, and the Redblacks as a whole. After the team blocked offensive coordinator Jaime Elizondo the opportunity to interview for a head coaching vacancy in Saskatchewan, Elizondo left to join Marc Trestman in the XFL, creating a hole in the coaching staff, and resulting in an inconsistent "offensive committee" to call plays from either Winston October or Joe Paopao. Also in free agency, Ottawa General Manager Marcel Desjardins did not extend key components of Ottawa's offense from the past several seasons, including all star players William Powell, SirVincent Rogers, and Greg Ellingson, as well as starting quarterback Trevor Harris, getting into contract disputes with the latter two. With Sinopoli as the only remaining star player on offense, the team struggled and finished dead last with a record of 3-15. Sinopoli's statistics suffered from playing with three different quarterbacks, and the lack of a running game; no Ottawa running back scored a touchdown all season. Sinopoli managed 72 catches for 671 yards and 3 touchdowns.
Career statistics
Awards and honours
In 2016, the Ontario Sports Hall of Fame recognized Brad Sinopoli as the 2015 Syl Apps Athlete of the Year Award recipient. The award celebrates the contributions of top athletes in Ontario, and is awarded to the athlete who has made an outstanding and memorable contribution to Ontario sports during the previous calendar year. The online public vote to determine the award recipient concluded on March 31, 2016 with Sinopoli edging out other top professional competitors such as Andre De Grasse, Brooke Henderson and Andrew Wiggins to win. He received nearly 30% of total votes cast.
