Career
Born in Eibar, Gipuzkoa, Basque Country, Seguín joined Athletic Bilbao"s youth setup in 2005, aged ten. He made his debuts as a senior with the farm team in the 2012-2013 campaign, in Tercera División. On 26 May 2014, after scoring 11 goals for Basconia, Seguín was promoted to the reserves in Segunda División B. He appeared in 35 matches and scored three goals over the course of the season, as the B-side returned to Segunda División after a 19-year absence.
Seguín made his professional debut on 24 August 2015, starting in a 0–1 home loss against Girona Football Club.