Johnson (knee) was in Miami for a visit on Wednesday, Adam Beasley of the Miami Herald reports.
The Dolphins lost out on C.J. Anderson when the Broncos matched the contract offer Tuesday but they are still looking for a veteran back to compete for the starting job with Jay Ajayi. Johnson had a productive season for Arizona last year rushing for 814 yards before suffering a broken leg in Week 12 that prematurely ended his 2015 campaign.