Aged 16, he joined local giants Real Sociedad's youth ranks, going on to play his entire career there and being known as "El pulpo" (Octopus in English).

[9] He still returned strong for three more seasons, helping Real Sociedad to two consecutive Copa del Rey finals before retiring at 35 with a total of 414 appearances (551 overall); after that, he remained apart from the football world.

[12][13] In the 1982 World Cup, Arconada fumbled a cross from Billy Hamilton of Northern Ireland, dropping the ball for Gerry Armstrong to score the only goal in Valencia and help his team to win the group.

[16][17] At the 1984 European Championships, Arconada's blunder resulted in the opening goal for hosts France in a 2–0 final loss: he appeared to have smothered a free kick from Michel Platini under his chest in a diving save, but the ball slid off under his body and rolled slowly into the net; despite his reputation as a world-class goalkeeper, several years later he was still widely remembered for the error, known as "Arconada's goal" in Spain.

[22] A severe cruciate ligament injury while playing for Real ousted him from the final stages,[9] being replaced by fellow Basque Andoni Zubizarreta.