The Bengals worked out free agent Rod Smith, Field Yates of ESPN reports.
Smith, 27, is the brother of Cowboys linebacker Jaylon Smith.
The running back has spent most of the past four seasons in Dallas and backed up Ezekiel Elliott the past three seasons.
Smith entered the NFL as an undrafted free agent in 2015, signing with the Seahawks. He played one game with Seattle that season after earning a promotion from the practice squad.
The Cowboys claimed him off waivers later that season.
He has started two of 49 games played and has 636 yards from scrimmage and six touchdowns on 131 touches. Smith also has 65 career kickoff returns for a 21.7 yards average.