Hawkins confirmed the deal on Uninterrupted, the network developed by LeBron James and his business partner Maverick Carter, saying, "I'm super excited about the opportunity to join the reigning football champions. I exited Cleveland, and I said it was about joining a contender and the Patriots are the contender, the reigning champs. The program is top-notch and you get the opportunity to play with the best quarterback and the best coach in NFL history."
Hawkins added that he passed up on deals that "were probably double the compensation" with other teams.
"It's all about winning for me at this point, and putting myself in the best position to do so. I have my work cut out for me, it's an opportunity, and that's how I'm approaching it: Go in there, seeing how I stack up with the best, and try to earn my keep and prove my worth. Hopefully I can be a part of something special and kind of join that Patriots legacy."
To make room for Hawkins, the Patriots waived wide receiver Devin Street.
The Patriots announced the signing on Thursday, but did not disclose terms.
Hawkins, 31, worked out for the team last week. He most recently made headlines by earning his master's degree from Columbia with a 4.0 GPA.
The Browns had released him on Feb. 27 in a move the wide receiver agreed was best for all parties.
The Browns are a young team that drafted four receivers a year ago. Even though none had an outstanding rookie season, the Browns wanted to give them a longer look.
Hawkins signed with the Browns as a restricted free agent in the spring of 2014. He led Cleveland with 63 catches and 824 yards in his first season, but had just 60 catches the past two seasons combined.
Hawkins played for the Bengals in his first three NFL seasons.
ESPN's Pat McManamon contributed to this report.