[3][4] Born in Tampa Bay, Florida,[5] Belfiore became enamoured of computers as a child through his experience with a Timex Sinclair 1000 belonging to the father of a fellow kid in his neighborhood.

[11] As part of this effort, Belfiore successfully negotiated a deal with US cable companies to enable PCs to consume and broadcast digital TV signals around the home.

[16] On October 8, 2017, in response to a Twitter question about Windows Phone, Belfiore broke Microsoft's silence about the platform by saying it will continue to be supported for bug fixes and security only, but no new features or hardware.

This clarified Microsoft's position that the platform, then having fallen below 1% market share, is on end of life support amid ongoing rumors of a "Surface Phone".

:([19]In the summer of 2013, Belfiore was named the leader of the "PC/Tablet/Phone" vertical within the Operating Systems Group at Microsoft,[20] responsible for delivering Windows 10 on PCs, tablets and phones.

This group significantly updated the Windows desktop experience, owned and created the Cortana digital assistant,[21] and created the "Continuum" feature set, which enables 2-in-1 PCs (like the Surface) to transform between "PC Mode" and "Tablet Mode";[22] and additionally enables Windows Phone devices to connect to a keyboard, mouse and monitor and work in a PC-like experience.

In August 2019, Belfiore and his wife Kristina joined the ownership group of Seattle Sounders FC, a Major League Soccer club.

[31] His work on Windows 10 earned him kudos as Stuff magazine's #16 innovator of the year for 2015[32] and in May 2013, he was recognized by Business Insider as the #10 Best Designer in Technology.