Six Nations chiefs confirmed the former England captain's appointment at their meeting held in Rome.
Beaumont's three-year term of office begins immediately and he succeeds Welshman David Pickering, who will remain on the council as Welsh Rugby Union representative.
Beaumont said: "It is a privilege to be involved with the biggest annual rugby competition in the world.
" I would like to thank the outgoing chairman, David Pickering, for his work over the last four years, and I look forward to working with him and the rest of the council."
Ireland's Pat Whelan was elected as Six Nations vice-chairman, also with immediate effect.
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The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
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The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
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The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.
