Prior to the 2011 NFL draft, Cannon was considered one of the top offensive tackle prospects[2] and was selected by the New England Patriots in the fifth round with the 138th overall pick.

The New England Patriots selected Cannon in the fifth round, with the 138th pick, acquired in a trade from the Houston Texans.

[6] Cannon's late selection in the draft is widely attributed to his diagnosis of non-Hodgkin lymphoma pre-draft.

Cannon began the 2011 season on the Non-Football Injury list as he recuperated from his chemotherapy treatment, which took place during the NFL lockout.

[8] Cannon played in all 18 of the Patriots' regular and postseason games during the 2012 NFL season, including one start in place of right tackle Sebastian Vollmer.

With his significant improvement and performance through the first 11 games of the season, Cannon signed a five-year, $32.5 million contract extension with the Patriots through 2021.

[11] For his performance in the 2016 season, Cannon was named second-team All-Pro by Pro Football Focus and The Associated Press.

With Cannon, the Patriots were able to reach Super Bowl LIII where they defeated the Los Angeles Rams 13–3.

[16] On September 9, 2019, in the Patriots Week 1 matchup against the Pittsburgh Steelers, Cannon sustained a shoulder injury in the fourth quarter, which may cause him to miss a couple of months.

[17] On July 28, 2020, Cannon announced his decision to opt out of the 2020 season, due to concerns over the ongoing COVID-19 pandemic.