The fly-half, who missed out on a place in the All Blacks squad for the World Cup, will leave North Harbour and New Zealand after the ITM Cup match against Counties Manukau this week.
North Harbour Rugby chief executive Brett Hollister said: "We've worked with the New Zealand Rugby Union to negotiate an appropriate release with Luke, including an early release fee,” North Harbour chief executive Brett Hollister said.
"We're obviously very disappointed that he is leaving during our 2011 ITM Cup campaign - as our season was planned on the expectation Luke would play for us.
"The reality is he wishes to start his new contract in Toulouse this month and for us that means finishing the ITM Cup season without him."
New Zealand general manager Neil Sorensen added: "While this is a disappointing end to Luke's career in New Zealand, we have agreed that this is the best outcome for everyone involved and we wish him well."