Born in Ondarroa, Biscay, Zubikarai joined Real Sociedad in 2003 at age 19, being assigned to the B team in Segunda División B.

[2] After Asier Riesgo moved to Recreativo de Huelva, Zubikarai was definitely promoted to the main squad but, after the former returned from his loan, both battled for second-choice status during the 2009–10 campaign.

[6] He continued to act as understudy to Claudio Bravo for the duration of his spell,[7] but was Real Sociedad's goalkeeper in the Copa del Rey, notably helping to a semi-final run in 2013–14.

[13] This exploit constituted the third-longest streak of its kind of all time – behind Mazarópi and Thabet El-Batal – as well as the longest of the 21st century, and of any European goalkeeper.

However, the club reportedly feared public reaction to the signing of a player whose father, Cándido, was affiliated with terrorist organisation ETA, and was sentenced to thirty years in 1989 for the murder of two civil guards.