Smith was not tendered by the Dolphins and has become an unrestricted free agent, Alain Poupart of the team's official site reports.
Smith went undrafted out of Michigan in 2017 and was on and off with the Dolphins throughout his rookie season, getting waived and subsequently re-signed twice before season's end. He ultimately finished the year having appeared in five games but never received a rushing attempt in his limited offensive action. Just 23 years old, Smith has youth on his side and should be able to land another contract this offseason with a team in need of running back depth.