Ayers' addition Wednesday makes him the 13th veteran the team has signed since free agency started.
Ayers had a career-high 5.5 sacks last season for the AFC champion Broncos. A 2009 first-round draft choice out of Tennessee and a New Jersey native, he is the fourth participant from February's Super Bowl, and the third from the Broncos, to join the Giants. The others are cornerback Dominique Rodgers-Cromartie and return specialist Trindon Holliday. Cornerback Walter Thurmond left Seattle to join the Giants.
The Giants lost defensive captain Justin Tuck to Oakland in free agency, leaving Jason Pierre-Paul, Mathias Kiwanuka and second-year pro Damontre Moore. Pierre-Paul was limited by injuries last season.
''This is a tremendous opportunity for me, coming to a great organization like this,'' Ayers said. ''They hate losing and they're always about getting better and preparing, and I've heard nothing but good things about the general manager and the owners, the coaches. Everyone speaks highly of them across the league. They're a blue-collar organization.''
Ayers played in 72 regular-season games with 27 starts for the Broncos and had 141 tackles (101 solo), 12 sacks and three forced fumbles.
The Giants have been the NFL's most active team in free agency. Along with Rodgers-Cromartie, Thurmond and Holliday, they have signed offensive linemen Geoff Schwartz, J.D. Walton, John Jerry and Charles Brown; defensive backs Zack Bowman and Quinton Demps; wide receiver Mario Manningham; linebacker Jameel McClain; and running back Rashad Jennings.
The Giants have also retained 10 of their own free agents - linebackers Jon Beason, Spencer Paysinger and Mark Herzlich; cornerback Trumaine McBride; safety Stevie Brown; kicker Josh Brown; quarterback Curtis Painter; running back Peyton Hillis; fullback Henry Hynoski; and defensive tackle Mike Patterson.