The move, announced on Sinofsky's personal blog on Thursday, is slightly surprising given Marc Andreessen, co-founder of the venture capital firm, has long been a critic of Microsoft, since Microsoft effectively crushed his Netscape Communications browser company in the 1990s.
Founded in 2009, Andreessen Horowitz is one of Silicon Valley's newest and most prominent venture funds, which has recently backed companies such as photo-sharing business Instagram and accommodation service Airbnb.
Sinofsky left Microsoft unexpectedly in November, just after he led the rollout of Windows 8, after an uncomfortable relationship with CEO Steve Ballmer.
He has kept a low profile since then, teaching a class at Harvard Business School. An agreement with Microsoft prevents him from working with direct rivals such as Amazon.com Inc, Apple Inc or Facebook Inc for a year.
"I'm especially excited to learn by spending more time with entrepreneurs and those creating new technologies and products," said Sinofsky on his blog. "Andreessen Horowitz is a VC firm that believes deeply in helping entrepreneurs and helping change the product and business landscape."
© Thomson Reuters 2013
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