The Indianapolis Colts reportedly used a two-year, $23 million contract to lure Stephon Gilmore to the Lucas Oil Stadium.
A source told ESPN's Adam Schefter that the deal includes a guarantee of at least $14 million for the former Patriots cornerback.
Indianapolis have looked to add experience to their roster ahead of the 2022 NFL Draft at the end of April.
The Colts also recruited former Philadelphia Eagles safety Rodney McLeod, announcing that deal on Thursday 14 April.
It has been an off-season of rebuilding for the Colts who saw defensive co-ordinator Matt Eberflus leave to take over as head coach at the Chicago Bears.
Indianapolis Colts chase Super Bowl
Experienced coach Gus Bradley comes in to replace Eberflus and marshall a defence that features five Pro Bowlers.
General manager Chris Ballard has moved the puzzle pieces around to refresh the defensive options for a team that see themselves as genuine Super Bowl contenders.
Ballard has traded corner Rock Ya-Sin for highly-rated edge rusher Yannick Ngakoue, he also signed corner Brandon Facyson, safeties Rodney McLeod and Armani Watts, and linebacker Brandon King.
Gilmore and the Colts appear to be a good match, with both looking to recapture former glory.
The five-time Pro Bowler's time at the Patriots was overshadowed by injuries and a nasty contract dispute.
Colts owner Jim Irsay had vowed to overhaul the roster after the team missed the playoffs in 2021.
"When we started this season 0-3, we knew the rest of this season would be an uphill climb.
"We all were hopeful we could dig our way out of the hole and reach the playoffs, and we should have.
"But we ended our season in perhaps the worst way possible and missed our chance to compete for history.
Irsay promised: "The buck stops with me, and this experience makes me even more determined to bring Indiana a contending team.
"We are already working toward the future, and I'm going to do whatever it takes to put us in a position to win next year and for years to come.
"As always, thank you for your support of the Colts in 2021. This was a rough way to end our year, but this bad taste will fuel and motivate us even more next season. I promise you there are some exciting days to come."