Both are on one-year contracts.
Sowell played in all 16 games last season on special teams and as a backup offensive lineman. The Cardinals claimed him off waivers in 2013 and he appeared in all 16 games, the last 11 as a starter, that year.
As an undrafted rookie free agent in 2012, he played in 10 games for the Indianapolis Colts.
Smith was among Kansas City's final roster cuts before the start of last season. In 2013, he was on the practice squad of the B.C. Lions of the Canadian Football League.