Brumbies first five-eighths Christian Lealiifano will play his rugby for Waikato next month.
His arrival helps offset the loss of former All Blacks lock Kevin O'Neill, who is to play for Super 15 expansion team Melbourne next year.
Waikato said the Chiefs player, with one test cap for the AllBlacks in 2008, will also not be available for Waikato in this year's national provincial competition.
The 2.01m lock has played 32 matches for the Chiefs and 20 for Waikato after earlier playing for the Crusaders and Canterbury.
"We are sorry to be losing such an experienced forward from our province. However, we are aware that comes with the territory in professional rugby," Waikato coach Chris Gibbes said.
"Kevin has been a great performer for Waikato and will be missed."
Lealiifano, 22, was born in Auckland and will arrive early next month to embark on a "one-off" campaign with Waikato.
"It is a unique opportunity to have a proven, quality Super 14 player from outside our region wanting to play for Waikato," Gibbes said.
"He is keen to carry on his good Super rugby form into our national provincial rugby competition.
"Christian is a skilful player and he is the type of guy who I'm sure will help inspire a lot of young players in our squad."
Lealiifano played six Super 14 games for the Brumbies this season before being sidelined with a knee injury.
He has now recovered from the rupture to his posterior cruciate and will be fully fit for the ITM Cup which starts at the end of July.
