Microsoft has signed Jason Holtman, the former lawyer who spearheaded Valve's Steam business for eight years before departing the company in February.
Holtman told GamesIndustry International that he will be "focusing on making Windows a great platform for gaming and interactive entertainment".
The former Steam businessman did not discuss his departure from Valve, which raised questions when the news first leaked online, due to his seniority at the company (to the extent that he spoke for the company at industry events).
"I think there is a lot of opportunity for Microsoft to deliver the games and entertainment customers want and to work with developers to make that happen, so I'm excited to be here," he added.
Holtman's move from Valve to Microsoft (both based in Washington) comes amid growing division between the two companies.
Valve company president Gabe Newell turned heads when last year he branded Windows 8 "a total catastrophe", and began porting Valve games onto the Linux platform.
Though Microsoft's commitment to the PC space has become a matter for debate, a spokesperson for the company told CVG last Friday that the Windows firm remained "fully committed" to desktops.
The Xbox One controller will be PC-compatible by 2014, Microsoft has said.