After another season with Siena, Taddei left on a Bosman free transfer and signed a five-year contract with AS Roma on 3 June 2005.

[4] On 4 April 2007, he scored the opening goal in Roma's 2–1 victory over Manchester United in the first leg of the 2006–07 UEFA Champions League quarter-finals.

On 5 March 2008, he scored a goal in a 2–1 away win over Real Madrid in the 2007–08 UEFA Champions League round of 16,[5] in which Roma qualified to play another quarter-final against Manchester United.

At the end of the season, the club and the Brazilian footballer didn't reach an agreement[citation needed] for a contract renewal and Taddei left Roma after 9 years, playing almost 300 games and scoring 31 times in all competitions.

On 21 July 2014, after having been a free agent for two months, Taddei signed a contract with AC Perugia Calcio in Serie B.

[9] Taddei has never been capped by the Brazil national team but, thanks to his Italian citizenship, he is also eligible to play for Italy.