Williams played the past four seasons with the Miami Dolphins.
Williams was mostly a backup with the Dolphins. He rushed for 477 yards in four seasons, including a career-high 181 last year. He was utilized frequently as a pass receiver in Miami, where he caught 85 passes, including 20 in 2017.
Ware, who led the Chiefs in rushing in 2016, missed all of last season with a knee injury and Williams is insurance in case Ware doesn't return for the start of the season.