The 6'6", 235-pound prospect is now the sixth defensive lineman to join Penn State's recruiting class of 2020.
Warren picked the Nittany Lions over Virginia Tech, Louisville, and Michigan, among others.
Johnson is the ninth-ranked player in Virginia and the 33rd-best cornerback in the nation.
Washington is the third wide receiver to join Penn State's recruiting class of 2020.
Single-game tickets will go on sale to the general public at 10 a.m. July 2.
James Franklin landed his second recruit within the hour with Amin Vanover's commitment on Friday night.