Bennett played a key role for the Grand Slam winning Wales U21 side and made two appearances for the senior side in the 2003 Rugby World Cup against Canada and Tonga.

Bennett enjoyed a successful 2006–2007 domestic season with the Ospreys; he made 23 appearances for the region and scored three tries, one in each of the Magners League, EDF Energy Cup and Heineken Cup campaigns.

Bennett was included in the national squad for the 2006 Invesco Perpetual Series, and came on as a replacement in Wales's victory over the Pacific Islands. Bennett was named in the 28-man squad for the two-Test tour of Australia in May 2007 but after aggravating a neck problem in the Ospreys' Magners League title-winning, final clash of the season was unable to play a part in the tour.

In June, Bennett was named in Gareth Jenkins's 41-man preliminary Rugby World Cup 2007 summer training squad. He made the final cut in August and played in Wales's Rugby World Cup warm-up game against England at Twickenham. He made one appearance at the 2007 Rugby World Cup tournament, as a replacement against Japan at the Millennium Stadium.

In November 2007 Bennett was included in Nigel Davies's starting line-up to face world champions South Africa in the Prince William Cup clash at the Millennium Stadium. And in January 2008 the hooker was selected for Warren Gatland's RBS Six Nations squad; Bennett started in the victories over England, Scotland and France and came on as a substitute against Italy, missing the clash with Ireland at Croke Park though illness.