Imanol made his professional debut on 16 August 2021, starting in a 0–0 away draw against Málaga CF.[5] He scored his first professional goal seven days later, netting his team's second in a 2–0 home win over SD Amorebieta.
On 14 July 2022, Imanol was loaned to SD Eibar in the second division for the season.[6] In February 2023, he suffered an Achilles tendon rupture, being sidelined for the remainder of the campaign.[7]
Back to Athletic in July 2023, Imanol was definitely assigned to the first team during the pre-season,[8] and made his La Liga debut for the club as a second-half substitute on the opening matchday of the 2023–24 season, a 2–0 loss to Real Madrid at San Mamés.[9]