After finishing his development at Basque giants Athletic Bilbao, he spent several years competing at amateur level in the region, on loan.

He was an undisputed starter from early on, contributing three goals in 39 games (almost 3,000 minutes) in his fourth year as the Valencians returned to La Liga after a 13-year absence.

[3] On 28 August 2010, Sendoa appeared in the 2010–11 opener, a 0–1 home loss against Athletic Bilbao, thus becoming the oldest rookie in the history of the Spanish first division (aged 34 years, 8 months).

[6] He finished his playing career with a two-year spell at Deportivo Alavés, helping the club to achieve promotion from the third tier in 2012–13.

In July 2019, Sendoa was named as Athletic Bilbao's match delegate, an administrative role which he had performed for the previous four seasons at Alavés; he replaced Andoni Imaz.