PARIS — From barren territory on the outskirts of Paris, Ladj Ly hit movie theaters last month with an urgent message: Multicultural France is here, it is real and it is not in good shape.

The message comes directly from his own experience. Mr. Ly, 39, the son of a garbage collector from Mali, has put his whole life into a sharp-edged film that depicts the harshness of the French capital’s immigrant suburbs — the banlieues — that has won applause from French film critics of all political stripes, made President Emmanuel Macron sit up and take notice, garnered Mr. Ly a top prize at Cannes and is France’s candidate for Best Foreign Language Film at the Oscars.

What sets apart Mr. Ly’s film, “Les Misérables,” is its intimacy. He is part of this ill-understood world, grew up in it and still lives there. Authentic films about the banlieues are rare in France. The last major one, Mathieu Kassovitz’s “La Haine” (“Hatred”), in 1995, was made by an outsider.

Mr. Ly’s film is different.

Before becoming a professional filmmaker, Mr. Ly was the child with the video camera in his pocket, filming rough police “interventions,” partly to protect the banlieues’ inhabitants and often suffering the consequences.