Internationally, Amorebieta played for Spain (where he spent most of his early life) at youth level, but later decided to represent his country of birth Venezuela as a senior, appearing for the nation at the 2015 Copa América.

Born in Cantaura, Pedro María Freites Municipality, Anzoátegui, Venezuela, Amorebieta joined Athletic Bilbao in 1996, aged 11; he met the club's eligibility standards having been raised in the Basque town of Iurreta and through his parents, both of whom hailed from the region.

[5][6] After progressing through the ranks – alongside Fernando Llorente[7]– including CD Basconia (the farm team) and Bilbao Athletic (the reserves), he made his first-team debut in 2005–06, becoming first choice in the subsequent La Liga seasons.

[12] The Premier League club officially announced him on 22 May,[13] and he made his debut on 14 September, coming on as a substitute for Kieran Richardson in a 1–1 draw against West Bromwich Albion at Craven Cottage.

[17] He scored his first goal for the latter on 8 May, replacing Lee Tomlin after 73 minutes and netting a last-minute winner for a 2–1 away win over Brentford in the play-off semi-finals;[19] he was unused in the final at Wembley Stadium, a 2–0 defeat to Norwich City.

[39] Amorebieta also appeared in four matches for the Basque Country national team (a non-FIFA affiliate), debuting against Venezuela in San Cristóbal, Táchira on 20 June 2007.

The friendly match, a 4–3 Basque victory, was the grand opening for the 43,000 all-seated Pueblo Nuevo Stadium, after two years of construction for the 2007 Copa América.