He spent the majority of his career with Sevilla, appearing in 414 official games over the course of 16 La Liga seasons (206 goals, best-ever in the club's history[1]), and also managed his main team on several occasions.

He moved to neighbouring Deportivo Alavés in the Basque Country subsequently, then to CD Málaga, staying one year with the latter team.

In 1943, aged 20, Arza continued in Andalusia and joined Sevilla FC, where he had his most enduring and successful spell, scoring a hat-trick on his official debut, a 5–2 home win against CE Sabadell FC on 26 September, and netting 57 goals in his first four seasons combined – in 1946 the club won its first ever La Liga championship, with the player contributing with 14.

Dubbed El Niño de Oro ("The Golden Boy"),[1] Arza scored a career-best 29 goals in the 1954–55 season, good enough for his first and only Pichichi Trophy.

He also worked with the club as match delegate in the 80s and 90s[1] and, as a coach, was also at the helm of RC Celta de Vigo (five separate seasons, four in the top division).