T-Mobile is a mobile network operator headquartered in Bonn, Germany. It is a subsidiary of Deutsche Telekom and belongs to the FreeMove Business alliance.

T-Mobile is a group of mobile phone corporate subsidiaries (all under the ownership of Deutsche Telekom) that operate GSM and UMTS networks in Europe and the United States. The "T" stands for "Telekom." Most subsidiaries of Deutsche Telekom have names beginning with "T-" like T-Home, T-Systems and T-Online. T-Mobile also has financial stakes in mobile operators in Eastern Europe. Globally, T-Mobile has 101 million subscribers, making it the world's sixth largest mobile phone service provider by subscribers and the third largest multinational after the United Kingdom's Vodafone and Spain's Telefónica.

T-Mobile International has a substantial presence in eleven European countries (Austria, Croatia, Czech Republic, Germany, Hungary, Macedonia, Montenegro, the Netherlands, Poland, Slovakia and the United Kingdom) as well as in the United States.

In recent years Deutsche Telekom attempted to acquire rival mobile network operator O2, but in 2006 it was acquired by Spain's Telefónica.

As well as kit sponsors for FC Bayern Munich, Ferencvárosi TC and West Bromwich Albion, and a supporting sponsor of Birmingham City F.C., T-Mobile is also a sponsor of several sports events, some of which carry the company name. For example, it sponsors the Austrian first division football competition, the T-Mobile Bundesliga. It was also the official global mobile phone carrier for the 2006 FIFA World Cup (football) in Germany and sponsored its own cycling team, the T-Mobile Team.