Christie has been the defence coach at Tasman for the past three years and the province has won the Mitre 10 Cup premiership in the past two years.
He will join Highlanders head coach Tony Brown and assistant coaches Clarke Dermody and Riki Flutey.
Christie played 30 games for the Highlanders from 2014-2017 and co- captained the team in 2016.
Highlanders chief executive Roger Clark said there were a lot of quality candidates but it was clear Christie had what it took to deliver a quality defence.
Christie, fresh from winning the Mitre 10 Cup with Tasman, is excited to begin his new role in the New Year.
"Obviously I am stoked to be able to work alongside Brownie, Derms and Flutes. The chance to coach defence for the Highlanders is an awesome opportunity and I can’t wait to get to Dunedin and get stuck into our work. It's already been a big year and this is a great way to finish it for me," he said.
