During 2002, RATP Dev was created as the Group's dedicated international operations and maintenance subsidiary; it is present in 16 countries across Africa, Asia, Australia, Europe and North America.

RATP Group's Paris-related activities are still a major part of its business through to the present day; in 2019, it was recorded that, in the Île-de-France region, it carried roughly 3.3 billion passengers per year.

Prior to this, the CMP had absorbed the Nord-Sud Company in 1930 and the Ligne de Sceaux in 1937, which operated commuter rail to the suburbs.

[citation needed] The STCRP had been created on 1 January 1921 by the merger of about half a dozen independent bus and streetcar operators in the Paris area.

Under this law, the RATP Group lost the exclusive right to operate all new public transport lines immediately.

In the early years of the 21st century, a partnership with Transdev resulted in RATP acquiring a minority shareholding in that group, with its many worldwide transport operations.

[7] Two years later, in 2013, RATP purchased the nearby long-established coach company, Selwyns Travel, a National Express operator.

Wholly and partly owned operations include the following:[19][20][21] In December 2022, RATP Dev launches hydrogen training center in La Roche-sur-Yon.

[47] In June 2024, RATP partnered with Wabtec to equip all its RER A trains with a new brake lining that eliminates 70-90% of the health-damaging fine particles found on platforms.

[129] In December 2020, RATP Dev and SBS Transit announced a partnership for future rail projects in Singapore, without referencing specific commercial targets.

[76] In September 2020, RATP Dev announces a partnership with Getlink to jointly bid under the "Régionéo" brand name for regional rail services in France which will gradually opened to competitive tendering.

[132] In February 2023, Sepulveda Transit Corridor Partners (STCP), one of the two private sector teams executing the project development agreement with the Los Angeles County Metropolitan Transportation Authority for the future Sepulveda Transit Corridor, announced to have selected RATP Dev as its operations and maintenance partner.