Les Ulis (French pronunciation: [lez‿ylis] ⓘ) is a commune in the Essonne department located in the southwestern suburbs (banlieue) of Paris, France.

Les Ulis is a new town located in the Île-de-France, in the south-west of the Parisian agglomeration and in the north-west of the Essonne department.

To the west is the residential area, a large part of which consists of 33 HLM tower blocks, grouped into four neighbourhoods.

The town was conceived and built in the 1970s according to the precepts of Le Corbusier by architects Robert Camelot, François Prieur and Georges-Henri Pingusson.

Line B of the RER runs through the Chevreuse and local bus services give access to the train stations at Orsay and Bures-sur-Yvette.

The discovery in 1977 of Bronze Age tools in the neighbouring town of Villejust suggests the possibility of pre-historic human occupation of the area that is today Les Ulis.

265 hectares of land comprising four farms, previously belonging to the communes of Bures-sur-Yvette and Orsay, were set aside for this housing project.

Road and utilities for the industrial zone were completed by July 1966, with the first business, AtoChem (part of what is now Total S.A.), moving in the following year.

Because this was significantly greater than the populations of both Bures-sur-Yvette and Orsay, which shared administrative responsibility for the town, a local plebiscite was held on 14 March 1976 to decide between three propositions: maintaining the status quo; creating a new commune comprising the three towns; creating a new commune for Les Ulis.

In March 1977, Paul Lorident was elected mayor of Les Ulis, whilst the town remained in construction.

He oversaw the building of a town hall, a market, a hybrid library and a cultural centre, named after the writer Boris Vian.