The 57-year-old ended his previous stint with rugby union's top international side in 2011 after seven years, opting to become assistant coach at Super Rugby side the Chiefs.
However, he will leave the Hamilton-based side to work at the international level again, while also helping all five New Zealand-based Super Rugby sides.
Smith is relishing the chance to return but revealed he had canvassed opinion with some of the current squad before accepting the role.
"I care deeply about the All Blacks," he said. "I'm excited to be back and looking forward to getting stuck in next year.
"When I was asked to be involved in the All Blacks again for 2015, it was a case of checking whether I had the support of my family, which I did.
"I also spoke to some of the senior players in the team and everyone was incredibly supportive."
Smith will work alongside head coach Steve Hansen, his assistant Ian Foster and fellow specialist coaches Mike Cron and Mick Byrne.
Hansen is delighted to have Smith back on board for the new year, which will see New Zealand try to defend their Rugby World Cup crown in England in September.
"He is one of the most astute coaches in world rugby and having worked with him in the past, we know just how valuable he is to any team he is involved in," said Hansen.
"Smithy will add another dimension to what is already a strong coaching group in what will be a big year for us. We look forward to welcoming him back into the fold.
"Smithy's role will be purely around defence but, as we do with all our coaches, we will tap into his vast knowledge of other areas of the game."