Johnson, 26, caught 28 passes for 328 yards and five touchdowns in his final season at Alabama State before going undrafted in 2014. The 6-foot-3, 225-pounds receiver began his professional career as a member of the Green Bay Packers' practice squad in 2015, and has also spent time with the Toronto Argonauts of the Canadian Football League. He signed a future contract with Seattle following the conclusion of the 2016 season, then was waived in May.