Turner will be in charge of Microsoft's global sales, marketing and services operations, along with fulfilment and IT operations.
The position of chief operating officer has been vacant since 2002, when Rick Belluzzo left after just a year in the post.
Microsoft has now made two high-level appointments from outside the technology industry this year, the first being chief financial officer Chris Liddel who joined from International Paper.
Microsoft chief executive Steve Ballmer said in an internal email obtained by Reuters: "Turner's experience as a proven leader of people in Wal-Mart's incredibly dynamic sales environment, his IT background as chief information officer of a world-class company, and his familiarity with our products and technologies as a Microsoft customer for more than a decade, uniquely qualify him to serve as our chief operating officer."
Despite remaining an attractive employer, Microsoft is unlikely to be creating as many millionaires since it abandoned the practice of handing stock options to employees in 2003.
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