The 2008–09 Primeira Liga was the 75th season of the Primeira Liga, the top professional league for Portuguese association football clubs.
Porto was the three-time defending champions and secured a fourth consecutive title for the second time in its history.
Boavista were also relegated as a punishment for their participation in a match fixing scandal in 2003–04 season.
Accordingly, Paços de Ferreira, which was originally scheduled to be relegated, was saved from demotion.
Leiria and Boavista were replaced by two promoted teams from Liga de Honra.