He began his career with Racing de Santander, and had spells playing for Zaragoza, Espanyol and Villarreal for La Liga totals of 233 matches and five goals.

Born in Potes, Cantabria, Álvaro was a product of local club Racing de Santander's youth ranks, and made his professional debut in the 2009–10 season, appearing in 23 games for the reserves in the Segunda División B and being relegated.

[11][12] Álvaro made his competitive debut for Villarreal on 15 September 2016, in a 2–1 home win against FC Zürich in the group stage of the UEFA Europa League.

[13] His first league appearance came ten days later in the 3–1 home defeat of CA Osasuna where he played 90 minutes and gave away a penalty which resulted in the opponent's goal.

[14] On 19 July 2019, Álvaro joined French club Olympique de Marseille on a season-long loan, with a mandatory purchase option of €5 million on 30 June 2020.

[18] In March of the following year, having ceased to be part of manager Jorge Sampaoli's plans, he profited from an international break to return to his country, and subsequently failed to report to training.