After much speculation, Hansen confirmed at a press conference in Auckland that he won't continue on beyond next year's event, where the All Blacks are attempting to become the first team to win three consecutive World Cups.
"I'm finishing," said Hansen. "I just think that after 16 years it is the right time to move on after the World Cup. It is the right thing for the team. We can have a fresh pair of eyes come into the team.
"The other major reason is that I want to spend more time with my family. They have given me unreserved support and now it is time for me to make them the sole focus and spend more time with them. One of the things about this role - and I am not bagging it - is that you become everyone's property and everyone has an opinion. Which I am fine with but it is hard on the other family members."
Hansen doesn't have any other coaching role lined up yet.
"I haven't thought about what I will do after the World Cup. It is such a great privilege to coach the All Blacks and I am focused on nothing more than the next 21 months as we have an incredible opportunity to do something that no other team has ever done before," he said.
"I have no regrets about making the decision and feel good about it. By doing it now it gives the Rugby Union plenty of time to find a replacement and run their process and it means I won't be getting asked about it every five minutes."
Hansen's plans have gripped the nation for months and now attention will turn to his successor. Ireland's Kiwi coach Joe Schmidt has ruled himself out in the short term, which means Hansen's assistant Ian Foster will be at short odds to take the reins.