Winslow had signed a one-year contract with the Patriots on Sept. 19, the team's interest coming after tight end Aaron Hernandez sprained his ankle in a 20-18 loss to the Arizona Cardinals three days earlier.
Winslow requested the Patriots release him after one game because he decided enduring a painful knee condition to play a limited number of snaps in what seems likely to be a very temporary role -- Hernandez apparently is healing faster than expected -- was not worthwhile, a league source told ESPN's Ed Werder.
There was no personality conflict between Winslow and the coaching staff, and he was considered a good fit for the Patriots' system, the source said.
"Yesterday, I had a discussion with Kellen," Patriots coach Bill Belichick said Friday. "We talked about several different things. At the end of that discussion, I felt that it was best that we release Kellen for personal reasons. So that's what we did, and our roster is currently at 52 (players) and we'll just go from there."
Winslow thanked the Patriots in a posting to his Twitter account Friday.
"I would like to express my gratitude to the Patriots organization and wish them a great season," he wrote in one tweet, following it with: "I'm lookin forward to my next opportunity in the NFL and continuing to play the game I Love!"
Despite the tweet, the source told Werder it would surprise nobody in the New England organization if Winslow never played again.
Hernandez has yet to return to practice, but he has been spotted in the locker room without the aid of crutches or a protective boot.
Winslow played four snaps in the Patriots' 31-30 loss to the Ravens on Sunday night, catching one pass for 12 yards and dropping another along the sideline.
In the days leading up to the game, Belichick noted Winslow's football intelligence as a factor in his being able to play in the game despite having been with the team for a short period.
"He's a pretty experienced guy, he's smart, he's (played) a lot of football," Belichick said.
One day after signing with the Patriots, Winslow had lauded the team's winning ways over the past decade and expressed excitement about the possibility of contributing. He also acknowledged that he plays in pain because of his knee.
"I would say, 'Will.' Overcome. The thing I concentrate on is not missing any games," he said.
Information from ESPN's Ed Werder was used in this report.