Bombardier Transportation was a Canadian rolling stock and rail transport manufacturer, with headquarters in Toronto and Berlin. It was one of the world's largest companies in the rail vehicle and equipment manufacturing and servicing industry, prior to being acquired by Alstom in 2021. Bombardier Transportation had many regional offices, production and development facilities worldwide. It produced a wide range of products including passenger rail vehicles, locomotives, bogies, propulsion and controls. In February 2020, the company had 36,000 employees, and 63 manufacturing and engineering locations around the world. Formerly a division of Bombardier Inc., the company was acquired by French manufacturer Alstom on 29 January 2021.

Canadian company Bombardier Inc. entered the rail market in 1970 when it purchased Lohner-Rotax of Austria. While Lohner built trams, Bombardier was more interested in its Rotax business, which built engines for its Ski-Doo snowmobiles. But Bombardier held onto the rolling stock business, and in 1974 secured an order from Société de transport de Montréal (STM) to build metro trains for the Montreal Metro. The core of the transportation group was formed when Bombardier purchased the Montreal Locomotive Works (MLW) in 1975. The purchase of MLW gave Bombardier a rail focused manufacturing facility, that had an established history of building locomotives, freight railcars, and passenger railcars.

With the purchase of the MLW, Bombardier acquired the LRC (Light, Rapid, Comfortable) tilting train design which it heavily marketed to both Amtrak and Canada's Via Rail, however, the program was only modestly successful with Bombardier selling about 100 LRC coaches to Via. In 1987, Bombardier bought the assets of two major US railcar manufacturers, Budd and Pullman-Standard. With these new assets, and no desire to remain in the business of building freight locomotives or freight cars, Bombardier sold off MLW to General Electric in 1988.

In the late 1980s Bombardier Transportation gained a manufacturing presence in Europe with the acquisition of a 45% share in BN Constructions Ferroviaires et Métalliques (whose principal facility was in Bruges, Belgium) in 1986. This was followed by the acquisition of the second-largest French railway manufacturer ANF Industrie with its main plant in Crespin in 1989. Bombardier Transportation had become by that time the leading North American producer of rail equipment which had sold 825 subway cars to New York City in the 1970s and 1980s.

Back home in Canada, 1991 brought a big expansion for Bombardier. The company was able to acquire the Urban Transportation Development Corporation (UTDC) from the Government of Ontario after its parent company Lavalin went bankrupt. In addition to the core UTDC assets, Bombardier also received the rail manufacturing division of Hawker Siddeley Canada which had been purchased by Lavalin and merged into UTDC. The Hawker Siddeley assets included a manufacturing plant in Thunder Bay, Ontario.

That same year in Europe, the company established its Bombardier Eurorail division consisting of ANF, BN, BWS (the former assets of Lohner), and the English bodyshell maker Prorail, which it had purchased in 1990. The company also owned the North-American rights to the French TGV through an agreement with GEC Alsthom. In 1992, the company acquired Mexico's largest railway rolling-stock manufacturer, Concarril, from the Mexican government.

The late 1990s also saw a major expansion in European operations. The company purchased Waggonfabrik Talbot (whose factory was in Aachen, Germany) in 1995 and Deutsche Waggonbau (DW) in 1998, which added factories in Bautzen and Görlitz, Germany along with a plant in Villeneuve, Switzerland which DW had purchased the prior year from Ateliers de Constructions Mécaniques de Vevey.

The company's biggest acquisition came just after the turn of the century when it purchased Adtranz from DaimlerChrysler. Adtranz was a sprawling multi-national company twice the size of Bombardier at the time, which had only become profitable in the months before the merger. The combination would make Bombardier the largest rail-equipment manufacturer.