The Bucs made the announcement Wednesday morning on their website.
Before the Bucs announced the deal, Sherman made the announcement on his podcast.
"I finally had enough conversations and came to a decision that I'm going to play for the Tampa Bay Buccaneers," he said.
According to ESPN, a source told the network's Adam Schefter that Sherman signed a one-year contract.
Sherman spent seven seasons with Seattle and was one of the main stars in the "Legion of Boom" defense.
He helped lead the team to a 2014 Super Bowl victory and was selected to five Pro Bowls in his 10-season career.
The cornerback became an unrestricted free agent in March after his third season with the San Francisco 49ers.
This is a developing story, and will be updated.
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