Ryan left the Crusaders last year to join Ian Foster's staff at the All Blacks and will continue in the role once Foster steps down at the end of the September 8-Oct. 28 World Cup in France.
Robertson appointed Ryan at the Crusaders in 2016 and the pair oversaw the Super Rugby side's run of six championship trophies in six years.
"Any role coaching the All Blacks is a huge honour and for as long as I have the opportunity to contribute to the legacy, I will do that to the best of my ability," Ryan said in a New Zealand Rugby statement on Wednesday.
"My full focus right now is Rugby World Cup, but I look forward to continuing the journey in 2024 and beyond."
Ryan will be joined by assistant coaches Leon MacDonald, Jason Holland and Scott Hansen, who take up their All Blacks roles in 2024.
Current Auckland Blues coach MacDonald will lead the attack with assistance from Wellington Hurricanes coach Holland, while Crusaders assistant coach Hansen will be in charge of defence.
Nic Gill, a key part of the All Blacks management group since 2008, will stay on as Head of Performance, New Zealand Rugby said.
"I've known Jason, Leon, Scott, Alfie (Holland) and Gilly for a long time and worked with them all at times during my playing and coaching career," said Robertson.
"They are a highly talented and motivated group who will bring different strengths to the table and who share a similar philosophy on the game.
"Like myself with the Crusaders, I know they all have important work to do in 2023 and their main focus will be on their current job in hand, but we will be ready to go from 2024."
