Johnson signed with the Dolphins on August 23, but had his contract terminated September 3 after recording 46 yards and a touchdown on 12 carries in the preseason.
Johnson will try to bolster a Miami running game that features Reggie Bush and rookie Daniel Thomas. The Dolphins, who opted against signing both Ronnie Brown and Ricky Williams as free agents, also released guard Ray Feinga to make room for Johnson.
The 31-year-old Penn State product was selected by Kansas City with the 27th overall pick of the 2003 draft and twice eclipsed 1,700 rushing yards in a season for the Chiefs. Despite starting only nine of the 16 games in 2005, he finished with 1,750 yards and 20 touchdowns, then followed with 1,789 yards and 17 scores the next season.
After falling out of favor in Kansas City during the 2009 campaign following a suspension for posting demeaning comments toward Chiefs coach Todd Haley, he was picked up by Cincinnati and appeared in seven games that season for the Bengals.
In his eight-year career, Johnson has run for 6,221 yards with 55 touchdowns and has caught 154 passes for 1,373 yards with six scores.