Amorebieta met Athletic de Bilbao's eligibility standards, having been raised in the region, and through his parents, both of whom are from the Basque Country. He made his first team debuts in 2005–06, becoming an undisputed first-choice in the subsequent La Liga seasons.
Amorebieta expressed his interest in playing for the Venezuelan national team (dubbed La Vinotinto); however, according to FIFA association rules, he should have switched codes prior to the age of 21, having previously played for the Spain in the youth categories.