"I love the club but I had to look after my career and I thought the best option for my future was to accept the contract at Penrith.
"My heart's still at the Vodafone Warriors. We're only just into the 2012 season and they'll have my full commitment for the rest of the year.
"I want to thank the club for the opportunity they've given me over the last four years."
Vodafone Warriors chief executive Wayne Scurrah said Brown has made a real mark at the club.
"I'll always remember our first meeting with him in Sydney and the impression he left," he said.
"He had so much enthusiasm and he brought that to the Vodafone Warriors. He has made a great contribution to the club, becoming a first-grade regular in his first season in 2009 and going on to play for the Kiwis as well."
Brown became Warrior No 151 when he made his debut against St George Illawarra in Wollongong in May, 2009. He'll make his 65th NRL appearance against the Sydney Roosters on Saturday night. Used as a back rower, centre and hooker, he has scored 15 tries so far.
He was first selected for the Kiwis for their 2010 Four Nations campaign but had to wait until the Anzac Test last May to make his debut, going on to play in each of the Kiwis' five Tests last year.
- HERALD ONLINE