He had been offered a one-year extension to his deal at Hamburg and was also linked with a move to Santos, but has now signed a two-year contract with the 2010-11 Qatari League runners-up.
The 37-year-old midfielder holds the record for appearances made by a foreign player in the Bundesliga, where he had spells with Bayer Leverkusen, Bayern Munich and most recently Hamburg.
He played for the Seleção 84 times, scoring six goals, and will follow in the footsteps of fellow Brazilians Juninho Pernambucano and Sonny Anderson, who have both previously represented the Qatari side.
