Chris Boyd has already announced he'll be leaving after the current season to take up a position with English club Northampton.
Jason Holland will be assistant coach with both he and Plumtree signing three-year deals.
Boyd and Plumtree arrived at the Hurricanes in 2015 after working together in Wellington and at the South African side the Sharks.
At that time Boyd said that he had planned that Plumtree would eventually take over from him.
The pair guided the Hurricanes to their maiden Super Rugby title in 2016 after finishing runners-up in 2015.
Hurricanes chief executive Avan Lee said the club was delighted with Plumtree's appointment which would be well received by fans and supporters alike.
"We're fortunate that someone of Plum's calibre has already been a key part of the Hurricanes environment. Having both him and Jason at the helm will certainly ensure some important continuity and familiarity, but more importantly, we know they are a formidable coaching combination.
"We know that these appointments will be pretty popular with our fans.
"This does mean that with both Plum and Jason working alongside Chris this year, we are in the best position for a smooth transition to a new management team and new season in 2019. In the meantime, it is important to acknowledge that Chris has done a fantastic job in steering the ship and he continues to keep everyone focussed on our current season," Lee said.
Plumtree, 52, played for Taranaki and Hawke's Bay before heading to South Africa to play for the Sharks.
His coaching career started with Swansea in 1997.