The deal is worth $50.6 million in new money and gives Howard the most guaranteed cash for a cornerback in NFL history.
Howard had three years and $39 million remaining on the five-year, $75 million contract he signed in 2020 but had grown discontent with the deal entering the 2021 season. The 2016 second-round pick requested a trade in July, saying he didn't feel "valued or respected" by the organization that drafted him.
His request came during an offseason in which Miami signed cornerback Byron Jones to a five-year, $82.5 million contract, making Howard the second-highest paid cornerback on his own team.
To alleviate his concerns, the Dolphins had slightly restructured Howard's contract after his trade request, which included rescinding his fines for skipping mandatory minicamp and promising to renegotiate his contract following the 2021 season.
"Xavien has done a lot of good things here for this organization," Dolphins GM Chris Grier said at the NFL's annual meeting last week. "I've known him for years. I was here when we drafted him. He was my second draft pick here. I'm looking forward to him being here and helping us win."
Howard intercepted five passes in 2021 and forced a pair of fumbles, one of which he returned for a touchdown. Since he entered the league in 2016, no other player has more interceptions than Howard's 27.