Born in Portugalete, Biscay, Aranguren joined Basque Country giants Athletic Bilbao's youth system at the age of 16, from neighbouring Sestao Sport Club.
On 18 November 1962, one month shy of his 18th birthday, he made his first-team – and La Liga – debut, playing the entire 2–1 away win against Córdoba CF, and finished his first season with 18 matches.
Aranguren would be an important defensive unit for Athletic in the following 11 campaigns, starting in 225 of the 229 games he appeared in the league and helping to win two Copa del Rey trophies.
After one year with Sporting de Gijón, Aranguren managed Athletic Bilbao during fifteen games in the 1991–92 season, following the dismissal of his former club teammate Iñaki Sáez.
In 1994, Aranguren returned to Alavés, winning promotion in his first year and staying with the team for a further two seasons, the second ending on 16 February 1997 following a 2–3 home loss against RCD Mallorca.