He was born in Paris in 1929 and went to art school to study painting. After some time working in advertising, he got a job in a psychiatric institution where he began experimenting in animation with the interns. It is at the psychiatric institution that he made 1960's Monkey's Teeth (Les Dents du Singe), in collaboration with Paul Grimault's studio, and using a script written by the Cour Cheverny's interns.
Another important collaborator of his was Roland Topor with whom Laloux made Dead Time (Les Temps Morts, 1964), The Snails (Les Escargots, 1965) and his most famous work, the feature length Fantastic Planet (La Planète Sauvage, 1973).
Laloux also worked with Jean Giraud (Mœbius) to create the lesser known film Les Maîtres du temps (Time Masters) in 1981. Laloux's 1988 film, Gandahar, was released in the US as Light Years. The US version was redubbed by Harvey Weinstein, from a screenplay adapted by Isaac Asimov. The US version was not as successful as the French version, grossing less than $400,000 on its release.