Johnson signed with Miami in late August to give the team another rushing option. He was a Pro Bowl selection for the Chiefs in 2005 and '06, when he eclipsed 1,700 yards rushing each year.
But his production has dropped off in recent seasons. He fell out of favor in Kansas City during 2009 following a suspension for posting demeaning comments toward Chiefs coach Todd Haley, and appeared in seven games for the Bengals that season. Johnson, 31, played in just two games for the Redskins last year.
The veteran Allen started 72 games for the Giants from 2001-05 and 53 games for the Dolphins from 2006-09. But he missed the latter part of '09 and all of 2010 because of injury.
To reach the NFL regular-season roster limit of 53 players, the Dolphins also terminated the contracts of safety Gerald Alexander, nose tackle Ronald Fields, fullback Lousaka Polite and tackle Ray Willis.
Miami also waived cornerbacks Vincent Agnew and Nate Ness; tight ends Brett Brackett and Mickey Shuler; wide receivers Patrick Carter, John Matthews, Julius Pruitt and Phillip Livas; guard Garrett Chisolm; quarterbacks Pat Devlin and Kevin O'Connell; tight end Dedrick Epps; linebackers Jonathan Freeny, Robert Rose, Quinton Spears and David Nixon; running back Nic Grigsby; tackles D.J. Jones and Matt Kopa; and safety Mark Restelli.
The Dolphins placed tackle Lydon Murtha on injured reserve.