The Dolphins settled on Garrard after being spurned by almost every free-agent quarterback they courted this offseason.
Both Peyton Manning and Matt Flynn chose to sign elsewhere after visiting with the Dolphins and new coach Joe Philbin. Former 49ers quarterback Alex Smith, who visited the team Sunday, will likely return to San Francisco.
Garrard sat out 2011 after being cut by Jacksonville days before the start of the season and eventually underwent back surgery.
The Dolphins have also informed safety Yeremiah Bell that he will be released to create cap space, a person familiar with the discussions told The Associated Press
The person confirmed the discussions to the AP on condition of anonymity because the Dolphins hadn't announced a move.
The Dolphins will save more than $4 million in cap space.
Bell, 34, has played his entire eight-year career with Miami and became a starter in 2006. He made the Pro Bowl in 2009 and led the team in tackles each of the past four seasons.