Agent Drew Rosenhaus said the deal includes $20.1 million guaranteed, a record for a tight end. With incentives, it could be worth up to $42.1 million.
Contract talks began soon after the Feb. 27 trade that sent Winslow, who participated in the Bucs' voluntary minicamp last week, to Tampa Bay from Cleveland in exchange for a second-round pick in this year's draft and a fifth-rounder in 2010.
"The Bucs were open to something long-term," Rosenhaus said. "It's nice to get it done."
Winslow was the sixth overall pick in the 2004 draft, and his career has been marked by plenty of highs, lows and controversy.
The 25-year-old had 219 receptions for 2,459 yards and 11 touchdowns in five seasons with the Browns, and the Bucs are counting on him to play a major role in an overhauled offense next season.
Winslow had 89 catches for 875 yards and three touchdowns in 2006 and followed with 82 receptions for 1,106 yards in 2007. He survived a serious motorcycle accident and battled injuries throughout his stay in Cleveland, and last season squabbled with the Browns' front office.
Jagodzinski told the Buccaneers' team Web site that he was excited about the opportunity to work with Winslow.
"We can put him in different spots and move him around to get the matchup that we want. He can get in and out of a cut like a receiver, now. He's good. He's really good. I'm really looking forward to working with him and he's been great. He's been great out at practice, asking a lot of questions.
"(Tight ends coach) Alfredo (Roberts) had him in Cleveland already, so he's very familiar with him and how he works and how he needs to be coached. I'm excited about him. I came off the field and I said, 'Man, we've got something good with him.'"
In addition to trading for Winslow, the Bucs placed the franchise tag on receiver Antonio Bryant, assuring him a salary of $9.8 million next season, and signed former New York Giants running back Derrick Ward to a four-year, $17 million contract.
Information from The Associated Press was included in this report.