The 34-year old Santos fan was at a bus stop heading home after Sunday evening's match.
Two car loads of Sao Paulo fans beat him with iron bars and kicked him to death. The man, who like the Sao Paulo fans belonged to an organised fan group, died in hospital.
The match ended 0-0.
Violence in and around Brazil's soccer stadiums has become an increasingly serious problem and more than 30 people were killed last year.
The World Cup in Brazil starts on June 12.