Born in Irun, Gipuzkoa, Sergio Francisco spent the vast majority of his 15-year senior career in the lower leagues, amassing Segunda División B totals of 254 games and 74 goals for four teams.
His debut in the latter competition took place on 17 September 2000, as he came on as a second-half substitute for Edgaras Jankauskas in a 4–1 away loss against RC Celta de Vigo.
[1] Having suffered an anterior cruciate ligament injury in September 2008,[2] Sergio Francisco retired at the end of the 2010–11 season, aged 32.
[4] He was appointed at Real Sociedad C in 2017, achieving promotion to the newly created Segunda División RFEF at the end of the 2020–21 campaign.
[5] On 31 May 2022, Francisco was named manager of Real Sociedad's reserves, recently relegated to the Primera Federación, in place of the departed Xabi Alonso.