After an unassuming spell with S.C. Salgueiros in Portugal (no appearances), Mahamat moved to France and remained in the country for four of the five following years, playing exclusively in amateur football and mainly with L'Entente SSG.
In the 2006–07 season, aged 23, he made his professional debuts, appearing for and G.D. Estoril Praia in the Portuguese second division.
In November 2007, Mahamat had unsuccessful trials in England with Hartlepool United and Bradford City.
Mahamat made his Primeira Liga debut on 15 August 2010, playing 90 minutes in a 0–0 home draw against U.D.
In May 2011, just weeks after the season ended, he was purchased by fellow league side S.C. Braga for an undisclosed fee;[2] on 1 June 2011 his transfer was confirmed, with the player signing a four-year contract[3] and reuniting with Beira-Mar boss Leonardo Jardim.