King, who brought up his 100th game for the Highlanders earlier this season, has signed a one-year contract and will move to the south of France at the conclusion of the Highlanders' season.
King first played Super rugby in 2003, making his debut off the bench for the Crusaders.
He moved south a couple of years later and has been part of the Highlanders side since.
He played his 100th game for the franchise against the Stormers in Cape Town, and is one of the most experienced players in this year's squad.
Former Highlanders lock Tom Donnelly, who is now at the Blues, has also signed for Montpellier for the coming season.
Otago captain Paul Grant played for the French Top 14 side last season but has since signed with English club Nottingham.
King's departure is a blow for the Highlanders as his experience and versatility was an asset to the team.
The 33-year-old's ability to play both sides of the scrum meant he was an automatic inclusion in the starting team or in the reserves most weeks.
Highlanders coach Jamie Joseph said earlier this week the side was constantly evolving and new players would be needed for next season.
He may find it tough to replace King, though it is a chance for an emerging prop to stake a claim.
King played for Otago, Southland and Taranaki in his provincial career.
Montpellier, which also has former All Black Rene Ranger on its books, finished in the top four of the French Top 14 last season before losing in the semifinals.
Montpellier has also announced the signing of French prop David Attoub and former Australian captain Ben Mowen.
