He played college football for the Washington Huskies and was selected in the sixth round of the 1983 NFL draft.
He signed with the Express immediately and started the last eight games of the 1983 USFL season catching 37 passes for 613 yards and three touchdowns.
In 1984, Allen started the season with the Express, however, was traded mid-season to the Michigan Panthers for a draft pick after eight games.
When the Panthers merged with the Oakland Invaders prior to the 1985 USFL season, Allen was not protected in the merger and was selected in the dispersal draft by the Baltimore Stars.
In his first game as a wide receiver for the Redskins against the St. Louis Cardinals, Allen had eight catches for 255 yards and three touchdowns, which is still a franchise record.