Richardson posted 507 receiving yards and four touchdowns over 17 games in Washington. He battled injuries throughout his tenure with the Redskins.
Washington will absorb a $6-million cap hit for the transaction. Richardson marks the second notable veteran to be released by the Redskins on Friday, as they also reportedly let go of high-priced cornerback Josh Norman.
Richardson, 27, served as a deep-ball threat for the Seattle Seahawks from 2014-17 before coming to the Redskins via free agency.