After retirement, Gallego turned his attention towards coaching. In 1994 Gallego was chosen to manage his former team, River Plate. In his first tournament as head coach, his "Millonarios" went undefeated to win the championship. The following year, he served as an assistant coach under Daniel Passarella, the Argentine national team's head coach, for the three-year tenure. After his experience with the national team, El Tolo returned to coach River Plate, with whom he won another championship, this time in 2000.