In 1924, Boulogne-sur-Seine was officially renamed Boulogne-Billancourt to reflect the development of the industrial neighbourhood of Billancourt annexed in 1860.

On that occasion, the communes of Auteuil and Passy were disbanded and divided between Boulogne-Billancourt (then called Boulogne-sur-Seine) and the city of Paris.

[4] In 1929, the Bois de Boulogne, which was hitherto divided between the communes of Boulogne-Billancourt and Neuilly-sur-Seine, was annexed in its entirety by the city of Paris.

Since then, Boulogne-Billancourt has been surrounded to the west, south and east by the Seine and to the north and north-east by the 16th arrondissement of Paris.

The automobile industry had a large presence with Renault on Île Seguin, as well as Salmson building both cars and aircraft engines.

It is also served by three stations on Paris Métro Line 9: Marcel Sembat, Billancourt and Pont de Sèvres.

[18] Prior to the September 1968 opening of Prévert, the first high school/sixth-form in Boulogne, an annex of Lycée La Fontaine served the city.

[20] The Association Eveil Japon (エベイユ学園 Ebeiyu Gakuen), a supplementary Japanese education programme, is located in Boulogne-Billancourt.