Career
Born in Barakaldo, Biscay, Basque Country, Álvarez joined Athletic Bilbao"s youth setup in 2008, aged 13. He made his debuts as a senior with the farm team in the 2013-2014 campaign, in Tercera División. On 26 May 2014, Álvarez was promoted to the reserves in Segunda División B. He contributed with 36 appearances and one goal during the season, as the B-side returned to Segunda División after a 19-year absence.
Álvarez made his professional debut on 24 August 2015, coming on as a second-half substitute for Jurgi Oteo in a 0–1 home loss against Girona Football Club.