[6][7] Rojo made his La Liga debut on 26 September 1965 in a 1–0 away loss against Córdoba CF,[8] and helped Athletic to win Copa del Rey trophies in 1969[9] and 1973.

[10] He totalled 414 games in the Spanish top flight, becoming the player with the second-most appearances in the Basque club's history, only behind José Ángel Iribar.

[4] He scored three goals in his nine years with the national team, but never took part in any major international tournament; he and his brother José Ángel appeared together in an exhibition game with Turkey on 17 October 1973, in the latter's sole cap.

[17] In 1982, aged 35, Rojo retired as a footballer and began a coaching career – a testimonial match was held in his honour, with Athletic Bilbao hosting the England national team.

[27] Rojo returned to the San Mamés Stadium for 2000–01,[28] but moved back to Zaragoza the following campaign, being replaced by Luis Costa on 22 January 2002 after a 4–2 away loss against Sevilla FC,[29] and ultimately being relegated from the top tier.