Keolis is one of the world’s leading public transport operators. The company is majority owned (70%) by the French state railway SNCF, the other shareholder being Caisse de dépôt et placement du Québec (CDPQ). Present in 15 countries (France, UK, Sweden, Australia, Germany, Belgium, Denmark, Norway, Netherlands, Canada, India, Middle East, Portugal, USA, Luxembourg and China) with 63,000 employees, Keolis develops tailored mobility solutions (automatic metros, tramways, trains, buses, coaches, ferries, self-service bicycles) adapted to local environments. The Group offers solutions and services via its subsidiary, Kisio. It is also the second leading car park operator in France thanks to its subsidiary EFFIA. In 2019, Keolis transported 3.4 billion passengers and generated 6.579 billion euros in revenue.

The Group has a large number of key references. It operates over 90 urban networks in France including those of Lyon, Lille, Bordeaux and Rennes. It is a partner in four rail franchises in the UK, carrying over 30% of the country's passengers. Its Swedish subsidiary is national number 2 in buses and number 1 in Stockholm. Its Australian subsidiary operates the Melbourne tram system Yarra Trams, the largest in the world with 250km of track. The Group also operates the Washington DC suburban lines of the Virginia Railway Express.

Keolis is the world leader in tram operations and the pioneer of the driverless metro, introduing the world's first in Lille in 1983.