Facebook announced Harvard alumna Sandberg's promotion to the eight-member board on Monday.
Forty-two-year-old Sandberg joined the social network in 2008 and oversees Facebook's business operations including sales, marketing, business development, legal, human resources, public policy and communications.
"Sheryl has been my partner in running Facebook and has been central to our growth and success over the years," Facebook founder and chief executive officer Mark Zuckerberg said in a statement.
"Her understanding of our mission and long-term opportunity, and her experience both at Facebook and on public company boards makes her a natural fit for our board."
Sandberg, whose profile in Facebook is considered second only to that of Zuckerberg, played a significant role in launching Facebook's initial public offer and working with business partners.
One of Facebook's most public figures, she is largely regarded as the perfect COO who complements Zuckerberg to work on important projects and chart the long-term future of the company he founded in a Harvard dorm room in 2004.
Commenting on her elevation to the so far man-only board of directors in the California-based
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