The hotel, which received the 2010 Corporate Trophy, was the only UK winner among the 13 categories of the Relais & Chateaux annual awards.
The Corporate Trophy, sponsored by Glenmorangie, was introduced in 2005 to recognise properties that distinguish themselves by providing high-performance event facilities and hospitality to business groups.
Chewton Glen managing director Andrew Stembridge said: "This is yet more wonderful recognition and highlights the fact that we look after business groups and parties as well as we do individuals."
Relais & Chateaux also unveiled Stembridge as the newest member of its board of directors after he was elected to join the nine-strong executive committee. He said he was "honoured and delighted" by the appointment.
These are the latest in a series of accolades for the Hampshire hotel, which was voted Best Incentive Hotel in C&IT's inaugural Hot List.
Earlier this week, it was named best British Luxury Service Brand at the 2009 Walpole Awards for Excellence, whose judging panel included GQ editor Dylan Jones and celebrity chef Marcus Wareing.
Meanwhile, Relais & Chateaux announced that 31 properties had joined its collection of more than 400 leading hotels around the world, including The Connaught, in London, and the Cliff House Hotel, in Waterford, Ireland.