Stellini played for Novara (Serie C2), Spal (Serie C1) before joined Ternana of Serie C2 in October 1996. He won promotion twice for the team to Serie B in summer 1998. In summer 2000, he joined Como of Serie C1, he won promotions again, reaching Serie A in 2002. he made his Serie A debut on 14 September 2002 against Empoli F.C..
In summer 2003, he joined Modena but suffered from leg injury. After played just twice, he moved to Genoa. For Genoa, after the scandal made the promotion to Serie A became relegated to Serie C1, he stayed with the club and also played 4 times in the promotion playoffs.
In June 2011 he passed the category 2 coaching exam. Early before, he was hired as a member of Antonio Conte's coaching team at Juventus.