Webb was a restricted free agent and the Ravens had given him a first-round restricted tender worth about $2.7 million.
The cornerback will be heading into his fourth season after being drafted in the third round of the 2009 draft.
Last season, his first as a full-time starter, Webb led the Ravens in interceptions with five, including a touchdown against the Jets in Week 4. He recorded 67 tackles.
In the playoffs, Webb recorded three interceptions, including two against Tom Brady of the Patriots, which led the team.
I wrote Wednesday that the Ravens were negotiating with Webb and three other players they would like to extend - quarterback Joe Flacco, running back Ray Rice and cornerback Cary Williams. It appears one of those deals is done.
Update: The NFL Network reports the deal is worth $50 million with a $10 million signing bonus and $20 million guaranteed.