Álvarez began his club career in Argentina in 2008 with Vélez Sársfield. His performances earned him a move to Italian club Internazionale in 2011, where he remained until 2015. He joined English side Sunderland on-loan during the 2014–15 season, a move which was to become permanent should Sunderland retain their place in the Premier League for the following season. The deal ended in a legal dispute with Inter over the contract with the Court of Arbitration for Sport later ruling in Inter's favour. He returned to Italy, joining Sampdoria as a free agent in 2016. At international level, Álvarez was a member of the Argentine squad that reached the 2014 FIFA World Cup Final.