In 1943 Yves Allégret's brother, Marc gave Gérard a small role in Les Petites du Quai aux Fleurs. The movie was to be shot in sunlit Nice, with six pretty girls evoking the charm of Paris in the main roles. With the war and the fear of the Gestapo in the background, the local palaces were occupied by rich refugees. Even in this atmosphere Gérard would be very cool about his role, despite the fact that because the ladies were to be shown always from the front, he would have to stand with his back to the camera most of the time. The movie did not reach any kind of success and remains to be known (incorrectly) as Gérard Philipe's first movie appearance.
In 1943, the cast of Jean Giraudoux's play, Sodome et Gomorrhe was almost complete, with only the Gardener and the Angel missing. The director of the play, Douking had seen Gérard in Lyon and wrote to him about the roles, but Gerard did not reply. They accidentally met on the metro some time after that, and hours later Gerard was already reading out the role of the Gardener. It had not yet been decided which role he would actually get. When asked for her opinion, Edwige Feuillere, the main actress in the movie said: "Him, a gerdener? But he is an angel!" Gérard took to transforming himself into his character with an enthusiasm and efficiency rare for an actor so young. For eight months he played his role faithfully, while trying to keep his personal life to himself. He did not neglect his friends and colleagues, either: his wonderfully told stories would be constant help for others to forget the horrors of bombings.
Gerard did not become conceited at the raving reviews he received from the press and public; he said he was still young and had no "technique". In October he was admitted to the Conservatory, and the following year he met George le Roy, who was more open to avant-garde and was not very conventional in taste. Gerard started attending his classes and would ask his tutor's professional opinion at all stages of his later career. Stagewise he was involved in the comedy Au Petit Bonheur by Marc-Gilbert Sauvageon in 1944, and a year after that in Fédérigo by Mérimée, in which play he starred next to Maria Casares, who would later on be his partner several times in his career.
After the liberation of Paris, Gerard joined the FFI, and Georges Lacombe gave him a double role in Le Pays Sans étoiles, a movie considered unique in its time, for rarely did French cinema turn towards the science-fiction in the first half of the twentieth century. It tells of the adventures of a notary clerk in a supernatural world, and Gérard was scared he would not come up to expectations. He need not have been: both the audience and the press praised Gérard unanimously.