In May 2011, Bustinza was promoted to the reserves in the Segunda División B. He appeared regularly for them the following campaigns, scoring a career-best five goals in 2012–13.[3]
On 15 July 2014, Bustinza was promoted to the Basques' main squad in La Liga.[4] He made his debut in the competition on 25 August, coming on as a late substitute in a 1–0 away win over UD Almería.[5]
Bustinza was handed his first start for the Lions on 2 May 2015, being sent off in the 93rd minute of the 0–0 draw with Atlético Madrid for two bookable offences.[6] Later that month, he played the full 90 minutes in the final of the Copa del Rey against FC Barcelona, a 3–1 loss.[7]
Leganés
On 22 July 2015, Bustinza was loaned to Segunda División side CD Leganés in a season-long deal.[8][9] The following 18 July, having contributed 1,134 minutes in all competitions to a top-flight promotion, he signed a permanent three-year contract after cutting ties with Athletic.[10][11]
Bustinza scored the first of two goals in the Spanish top tier on 21 February 2018, but in a 1–3 home defeat to Real Madrid.[12][13]
In November 2023, Bustinza started training with SD Amorebieta.[16] On 18 January 2024, he agreed to a deal at the second-division team.[17]
International career
Bustinza made his debut for the unofficial Basque Country national team in May 2019, in a 0–0 draw away to Panama for which a small, youthful and inexperienced squad was selected.[18][19]
^Funqueiro, Lucía (24 June 2022). "El Málaga pone el ojo en Bustinza" [Málaga set their sights on Bustinza] (in Spanish). Grada 3. Retrieved 4 July 2022.
^López, Jesús Fernando (25 October 2014). "Etxeita da aire al Athletic" [Etxeita gives air to Athletic]. Marca (in Spanish). Retrieved 27 October 2014.
^Malagón, Manuel (2 May 2015). "El Atlético llega tarde" [Atlético arrive late]. Marca (in Spanish). Retrieved 16 June 2015.
^Siguero, Santiago (30 May 2015). "Messi es el Rey León" [Messi is the Lion King]. Marca (in Spanish). Retrieved 16 June 2015.
^"Bustinza, cedido al Leganés" [Bustinza, loaned to Leganés] (in Spanish). Athletic Bilbao. 22 July 2015. Retrieved 22 July 2015.
^González, Raúl (19 July 2016). "Unai Bustinza, el soldado de Butarque" [Unai Bustinza, the soldier of Butarque] (in Spanish). Sphera Sports. Retrieved 27 February 2024.
^Guerreiro, Daniel (9 November 2023). "Bustinza se entrena con el Amore" [Bustinza trains with Amore]. Diario AS (in Spanish). Retrieved 18 January 2024.