The Dolphins also waived tight end Lorenzo Diamond.
Because of the 37-year-old Seau's hefty contract, his release had been expected. He missed 17 games the past two years due to injury, finishing both seasons on injured reserve, and an Achilles tendon injury limited him to seven games in 2005.
"Ideally, we would like to keep many of those players on our roster, but we are simply not able to do that," coach Nick Saban said.
Seau, a 16-year veteran, spent the past three seasons with Miami after being acquired from San Diego.
Seau has said he wants to play this year, even if it's not with Miami. His agent, Marvin Demoff, didn't return calls seeking comment.
Diamond, a two-year veteran, played in every game as a reserve last season and caught eight passes.