Mitchell's four-year contract is worth $16 million with $9 million guaranteed, according to the Miami Herald.
"I would like to welcome defensive tackle Earl Mitchell to the Miami Dolphins," said Dolphins general manager Dennis Hickey.
"Earl's production at the defensive tackle position speaks for itself. He is a productive and talented player who has a great passion for the game. The addition of a veteran like Earl will help bolster our defensive unit as a whole as well as adding another piece to the defensive front."
The 6-foot-3, 300-pound Mitchell joins Miami after spending the past four seasons with the Houston Texans.
Mitchell started 14 games and registered career highs of 48 tackles and 1 1/2 sacks last season.
Selected by Houston in the third round of the 2010 NFL Draft, Mitchell has recorded 134 tackles and 3 1/2 sacks in 63 career games.