[3] In July 2010, Herrerín decided to leave Athletic in search for "a new life in football", signing a contract with Atlético Madrid and spending two full seasons with the reserves also in the third division.

[17] On 30 November 2016, after being overtaken by Kepa Arrizabalaga, Herrerín was loaned to fellow top-tier side CD Leganés until the end of the season, mainly as a replacement for injured Jon Ander Serantes.

[18] On 19 January 2018, already back at Athletic and during a domestic league fixture away to Getafe CF, he conceded two penalties by tripping opposing forwards, saving the second kick in an eventual 2–2 draw.

[26] He made his debut the following 3 January in a 3–0 win at CF La Nucía of the Primera Federación in the Spanish Cup's last 32, playing the final 13 minutes in place of Giorgi Mamardashvili.

[27] On 21 July 2023, Herrerín joined several compatriots at Cypriot First Division side AEK Larnaca FC,[28] including manager José Luis Oltra.

[30] Herrerín 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.