Microsoft Mobile was a subsidiary of Microsoft involved in the development and manufacturing of mobile phones. Based in Espoo, Finland, it was established in 2014 following the acquisition of Nokia's Devices and Services division by Microsoft in a deal valued at €5.4 billion, which was completed in April 2014. Nokia's then-CEO, Stephen Elop, joined Microsoft as president of its Devices division following the acquisition, and the acquisition was part of Steve Ballmer's strategy to turn Microsoft into a "devices and services" company. Under a 10-year licensing agreement, Microsoft Mobile held rights to sell feature phones running the S30+ platform under the Nokia brand.

Originally Microsoft had established a major partnership with Nokia in 2011, in which the company exclusively produced smartphones using the Windows Phone platform, and promoted Microsoft services on its feature phone products (including Bing search). Microsoft also licensed Nokia Maps data for its own mapping services. While Nokia's resultant Lumia range had the largest market share out of all Windows Phone vendors, Nokia's overall market share was falling rapidly due to competition from other major vendors, resulting in a dire financial situation. In September 2013, Microsoft announced its acquisition of Nokia's devices and services businesses, which closed with the formation of a Finnish subsidiary, Microsoft Mobile. On smartphones, the Nokia name was phased out in favour of Microsoft branding on future Lumia products.

While the Lumia range continued to be successful, especially with low- and mid-range devices targeting emerging markets, sales of both Microsoft-manufactured smartphones and feature phones began to see major declines, due primarily to the rapidly-deflating market share of Windows Phone. In 2015, Microsoft took a US$7.8 billion write-down on the Nokia purchase, and announced layoffs of 7,800 employees, primarily within Microsoft's phone business. In May 2016, Microsoft abandoned its mobile business, selling the Nokia feature phone line and trademark rights to the Finnish startup HMD Global, and announcing that it planned to cut up to 1,350 positions in Finland and focus on offering its productivity services on competing mobile platforms. In 2017, Microsoft executive Joe Belfiore revealed that Microsoft had ceased the development of new Windows phones and new features for Windows 10 Mobile, citing the losses in market share and lack of app development.