The Browns filled a gaping offensive hole by signing Watson to a three-year, $12 million contract that includes $6.35 million in guaranteed money, a league source told ESPN NFL Insider Adam Schefter.
Watson spent the past six seasons with the New England Patriots, where he previously worked with Browns coach Eric Mangini and offensive coordinator Brian Daboll.
"We viewed Ben as one of the top all-around tight ends in the free-agent market," Browns general manager Tom Heckert said.
"Because of his athleticism and intelligence, he has proven valuable as both a receiver and blocker during his career, and has performed well in both facets. He comes from a winning program in New England and possesses the traits that we like in a player. We feel as though he can help us in many different areas and we are excited about his addition to our team."
The Patriots never seemed overly aggressive when it came to returning Watson to the fold despite their large void at tight end. They have Robbie Agnone and Rob Myers at the position, and neither has played in a regular-season game.
Watson visited with Seattle on Monday and was in Cleveland on Thursday. The Browns didn't let him get away, as Watson signed the contract before boarding his return flight Friday morning.
Known more for his pass-catching and speed, Watson finished last season with 29 receptions for 404 yards and five touchdowns. Although it was a season in which the tight end was not a big part of the offense from a pass-catching perspective, Watson came up big in the season opener with two touchdown catches in a comeback win over the Buffalo Bills. Quarterback Tom Brady later said one of those touchdowns was the best catch of Watson's career.
Watson was a first-round draft pick of the Patriots in 2004 (32nd overall) and came with plenty of hype. He was touted as an out-of-this-world athlete who could bring a Tony Gonzalez-type element to the offense. That never happened, and the expectations created an uphill battle for him.
"No matter how wise you are as a rookie or second-year player, I think we definitely get caught up in the expectations we have and the expectations for other people, trying to please other people," Watson said in November after a strong start to the 2009 season. "As you get a little older, you sort of get to the point where you ask, 'What am I trying to please other people for? Why am I going home stressed out about what other people think of me?' You sort of move and grow a little past that."
Watson's growth in that area was evident in recent years.
In 2006, Watson had a career-high 49 catches in a season in which the team featured more two-tight end sets with him and Daniel Graham. The past three seasons, he was a nice complement in the team's three-receiver package, his speed sometimes threatening defenses down the middle.
Without him, the Patriots will have a dramatically different look at the position in 2010.
ESPNBoston.com Patriots reporter Mike Reiss contributed to this report.