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. From 1995, 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. In 2002, he coached
Independiente to a championship, ending the team's 8-year drought. In 2004, he returned to the Newell's Old Boys organization after a 23-year hiatus, and once again proved his worth as a head coach, winning a championship that very same year. With that, he became only the second coach ever to win the
Argentine Primera championship with three different Argentine clubs (along with
José Yudica, who did the same with
Argentinos Juniors,
Quilmes and Newell's). His success attracted attention from teams in other countries, notably from Mexico. After leaving Newell's Old Boys, Gallego was sought after by a myriad of clubs, including
San Lorenzo de Almagro, but chose
CD Toluca in Mexico. Despite being overtly criticized by the media and his team's own fans for his defensive style and benching of established players in favor of younger, inexperienced players – his scheme paid off and Toluca won the Apertura 2005 championship in Mexico, and was named Best Coach of the championship. In 2007 Gallego resigned as coach for Toluca and said he wanted some time off to be with his family and be away from soccer for a while. His time off did not last long, as a juicy offer from
Tigres UANL made him change his mind and take over for
Mario Carrillo as coach. After an unsuccessful spell and a streak of bad results he was sacked in February 2008. In March 2009 he returned to Independiente to take over from
Miguel Santoro, and signed until June 2010, but did not end up winning any championships nor renewing his contract. In February 2011 he began a new tenure in
Colo-Colo of Chile, which finished on August of that same year. ==Career statistics==