Unai Lopez was born in the Basque city of Donostia and showed great promise at an early age when he joined famous youth academy Antiguoko. In 2010 he made the switch to Real Sociedad and immediately looked to become on of the top young players but, after just one year, he decided to leave to attend Lezama which caused a big stir among the two rival clubs. López worked his way up through the academy and was eventually promoted to the first team in the summer of 2014 and made his debut on 27 August, 2014 in a 3-1 win over Napoli in a Europa League qualifier match. Due to having competition in front of him in the squad, the midfielder has spent time on loan at Leganés and Rayo Vallecano and at the later he performed as one of the best players in the Segunda in the 2017/2018 season. After returning to Athletic he was rewarded with a new contract.
Unai López is under contract through 2022 and his deal contains a €45 million release clause.