Johnson signed a contract with the XFL's Los Angeles Wildcats on Friday, Kevin Seifert of ESPN.com reports.
Johnson appeared in four games for the Redskins last season (three starts), completing 57 percent of his passes for 590 yards, three touchdowns and four interceptions. He also played for the Buccaneers, Browns and Bengals in his NFL career. A stipulation in Johnson's contract bars him from participating in the NFL for the duration of the season in order to attend next month's XFL minicamp.