The Cardiff man was honoured for his outstanding performances against Fiji, Canada and New Zealand.
"I am surprised at getting this award, it is a big honour for me," said Williams as he received the award at a luncheon in the Millennium Stadium.
Williams has won a total of 28 caps since he made his international debut against the Barbarians in August 1996
The Former Wales Under-21 captain level played club rugby for his home-town of Pontypridd before joining Cardiff in June 1999.
And he is no stranger to awards - winning the club's official Player of the Year award in his first season at the Arms Park. Williams has been club captain since the start of the 2002-3 season.
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