Quinn reached an agreement on a deal after a tryout and is expected to compete with Matt Moore for the Dolphins' backup job behind starter Ryan Tannehill. Moore has been nursing a sore shoulder and didn't play in the first exhibition game last week, but he practiced Monday.
Quinn was with the Seahawks, Rams and Jets last year but didn't play. He is 4-16 as a starter and has thrown 12 touchdown passes and 17 interceptions, including two touchdown passes and eight interceptions in 2012, when he started eight games for the Chiefs.
''I feel extremely blessed for the opportunity to be a part of the Miami Dolphins!'' Quinn tweeted. ''Thank you for all of the well wishes. Fins Up!''
Quinn was a star at Notre Dame and the 22nd pick in the 2007 draft by the Cleveland Browns after being widely projected to go higher. Fans at the Dolphins 2007 draft party booed when the team passed on Quinn with the ninth pick and instead took receiver Ted Ginn Jr.
Moore, due to make $4 million this season, has 25 career starts but played in only three games in Joe Philbin's first two seasons as the Dolphins' coach.
Quinn has a career passer rating of 64.4. Moore's is 79.3