Taghmaoui was born in the Parisian suburb of Villepinte, into a large family of nine siblings. His parents were Moroccan immigrants of Berber ancestry. Taghmaoui grew up in Aulnay-sous-Bois, in the quartier Rose des Vents. He dropped out of school to become a boxer and rose as high as number 2 in his weight class in France.

Later he met Mathieu Kassovitz and together, they co-wrote the script for the award winning film La Haine (about race and violence in the suburban ghettos of Paris). Taghmaoui also played one of the main characters in the film and was nominated for a César Award in 1996 (Most Promising Actor) for his performance. He has performed in many films since then. He speaks five languages and he has pursued an international career, making films in Italy, Germany, Morocco and the United States. He divides his time between Los Angeles, France and Morocco.

Taghmaoui recently starred in the 2008 film Vantage Point playing the leader of a terrorist group that plotted to kidnap the U.S. president. Taghmaoui is again working with Matthew Fox as a guest star in the ABC TV show Lost.

In Morocco acted in Djinns a film about the Algerian War alongside Thierry Fremont.