London born McKenzie joined Calvisano from London Wasps in 2007 having won the European Challenge Cup with Wasps in 2003 and was part of the Wasps squad which went on to the lift the Heineken Cup at Twickenham in 2004.
“We are delighted that Hugh is staying with us at the Dragons,” said Dragons Rugby manager Robert Beale.
“He is a talented young player and although he has struggled with injury this season, we consider him to be very much a part of the future of the side at Rodney Parade.
“Ali will be a great addition to our squad. He has plenty of experience of big games from his time at London Wasps and he will certainly reinforce our already quality front row.”
