Terms weren't disclosed, but a source told ESPN NFL Insider Adam Schefter that Williams agreed to a three-year contract.
"It's going to be awesome. I'll be glad to join those guys and help those guys with whatever they need," Williams said in a statement. "I see where these guys are going and I think I can help them go to where they want to go. They had a great defense last year with a lot of young guys on the team. I'm a veteran guy and I hope I can take them to another level."
He took it a step further on Twitter, showing his excitement about pairing up with Haden in the Browns' secondary.
Fresh start. Cleveland it's time to RISE UP! This is our year! RT if you know me and @joehaden23 are about to lock up the AFC North!— Tramon Williams (@HighRizer38) March 17, 2015
Williams, who turned 32 on Monday, started every game for the Packers for the fourth time in five years. Dating to 2007, he has missed only one game.
"Tramon is a really good and consistent player," Browns general manager Ray Farmer said in the statement. "He has had success in this league because he's a pro's pro who believes great preparation leads to great performance. We are very happy to be able to sign a player of his caliber to our secondary."
In 2014, he tied for the team lead with three interceptions, giving him 22 since 2010 (including playoffs), which ranks second in the league among active players behind only Seattle's Richard Sherman.
Williams made $7.5 million last season in the final year of a four-year, $33 million contract extension he signed in 2010.
"I know this is a good spot for me," Williams said in the statement. "It carries the same tradition Green Bay had. I'm just ready for a new chapter in my life."
ESPN.com Packers reporter Rob Demovsky contributed to this report.