Pierschbacher signed a contract with the Eagles on Monday.
The 25-year-old was residing on Washington's practice squad but will now be joining a division rival. Pierschbacher hasn't seen game action this season but appeared in five games as a reserve for Washington in 2019.
Washington waived Pierschbacher on Saturday, Adam Schefter of ESPN reports.
The 2019 fifth-round pick appeared in five games with Washington as a rookie. He could still offer modest developmental intrigue as a reserve center or guard.