Number eight Nick Williams will join Cardiff Blues from Ulster on a long-term deal ahead of the 2016-17 Pro12 season.
The 32-year-old, hailed by his new head coach Danny Wilson as "an extremely physical and uncompromising forward", revealed he had been lured to Wales by the ambition of the region, who finished a disappointing 10th last season.
"It is a new challenge for me and I'm excited about what I've heard about what Cardiff Blues are looking to achieve, both on and off the field, in the coming years," he said in a statement.
"I spoke to Danny at length about the region and his plans. I'm now looking forward to using my experience to help the team and getting stuck in."
Williams started his career in his native New Zealand with Super Rugby team Auckland Blues and provincial side North Harbour, playing for both for four years from 2004.
He moved to Europe with Munster in 2008, winning the Pro12, then known as the Celtic League, in the 2008-09 campaign.
A two-year spell with Aironi of Italy followed between 2010 and 2012.
Williams, the brother of Samoa international Tim Nanai-Williams and cousin of All Black Sonny Bill Williams, has spent the last three years with Ulster.