Microsoft has set its sight on the lucrative $50bn 'affordable handset' market following its $7bn acquisition of Nokia.
Bill Gates's company completed the deal for the Finnish firm last Friday after announcing it in November 2013, and the unit will now be rebranded Microsoft Mobile, responsible for Lumia, Asha and Nokia X mobile phones and other devices.
About 25,000 employees from more than 130 sites across 50 countries will join Microsoft.
Nokia's manufacturing units in Chennai, India, however will not be transferred due to ongoing tax proceedings against the facility and an asset freeze by the Indian tax authorities.
Similarly, its Masan facility in Korea will not be transferred, affecting around 200 workers there.
Former Nokia president and CEO Stephen Elop will report to Microsoft CEO Satya Nadella, serving as executive VP of the Microsoft Devices Group, overseeing the devices business that includes Lumia smartphones and tablets, Nokia mobile phones, Xbox hardware, and the Surface tablet.
Nadella said: "The mobile capabilities and assets [Nokia's employees] bring will advance our transformation.
"Together with our partners, we remain focused on delivering innovation more rapidly in our mobile-first, cloud-first world."
Other senior executives from Nokia who will be transferred include Jo Harlow, Juha Putkiranta, Timo Toikkanen, and Chris Weber.
The deal also includes a patent transfer license.