 On 29 July 2005 Thiago Ribeiro returned to his native state, signing for São Paulo.He made his debut for the club on 14 August, replacing Amoroso in a 3–2 home win against Fortaleza, and scored his first goal on 16 October in a 6–1 away routing of Flamengo.On 19 November 2005, Thiago Ribeiro scored a hat-trick in a 4–2 home success over Figueirense.