The Redskins also announced Monday that Bob Slowik will move to linebackers coach after working with the secondary for the last two seasons.
Hilliard played 12 seasons in the NFL and spent this season as an assistant receivers coach for the Miami Dolphins.
He replaces Keenan McCardell, who was dismissed earlier this month.
The changes are among several to coach Mike Shanahan's staff this offseason. Former Tampa Bay Buccaneers coach Raheem Morris was brought in to coach the defensive backs, safeties coach Steve Jackson was let go, and linebackers coach Lou Spanos left to become UCLA's defensive coordinator.