The Dolphins promoted Smith from their practice squad to the active roster Wednesday.
Smith's addition seemed inevitable after the Dolphins' co-starting running back, Damien Williams, dislocated his shoulder in Sunday's loss to the Patriots, while third-string back Senorise Perry exited with a concussion. It's looking like the Dolphins will be without both players for the Week 13 matchup with the Broncos, so Smith could be called upon to fill the top backup role behind Kenyan Drake, the only other healthy back on the roster. It's expected that Drake will handle a three-down workload during the contest, so Smith may only be summoned on offense when Drake requires a breather.