The deal will see the Japan-based playmaker rejoin Canterbury for the 2026 National Provincial Championship and the Crusaders from the 2027 Super Rugby season.
"We're really pleased to have Richie re-committing to New Zealand Rugby," chief executive Mark Robinson said in a statement.
"He's a proven talent with a strong track record of performing on the biggest stages."
Mo'unga, capped 56 times for the All Blacks and a winner of seven championship trophies at the Crusaders, has been ineligible to play for New Zealand since leaving for Japan after the 2023 World Cup in France.
New Zealand Rugby restricts Test selection to home-based players to try to protect its domestic competitions from talent drain.
His former coach at the Crusaders, Scott Robertson, is now the All Blacks coach and has been vocal about wanting Mo'unga home and pushing for selection.
Mo'unga helped Brave Lupus Tokyo seal back-to-back Japan Rugby League One titles in June while playing with a fractured hand.
"He has this gift of bringing out the best in those around him and we can't wait to have him back in 2027," Crusaders CEO Colin Mansbridge said.
Mo'unga's return to New Zealand a year before the 2027 World Cup in Australia will be welcomed by home fans and give Robertson another option for the coveted No.10 jersey.
In Mo'unga's absence, Beauden Barrett has been Robertson's preferred option in most recent Tests, with Damien McKenzie the back-up playmaker.
Meanwhile, Leroy Carter's dream call-up to the All Blacks squad nearly turned sour when he discovered his passport had been chewed up by his dog days before leaving for Argentina.
Utility back Carter, named among the injury replacements in Robertson's squad, found his passport ruined on his bed and had to scramble to arrange a new one.
"I got my passport out to take a photo to send to the (team) manager and I just left it on my bedside table," the 26-year-old told New Zealand media.
"My partner went to the gym and left my dog home alone and it's gone down the hallway, jumped on the bed and just chewed up the passport and my teeth aligners.
"It was a bit of a shambles yesterday. I was trying to get an emergency one but I think it's all sussed (sorted) now.
"I thought it would happen to me, something like that, so no point getting stressed about it, just trying to sort it out."
Most of the All Blacks squad will fly out on Friday for Argentina where they play their Rugby Championship opener against the Pumas in Cordoba next week.
Carter, who represented New Zealand in rugby sevens at the Paris Olympics and won a bronze at the 2022 Commonwealth Games, earned his first All Blacks call-up after his debut season with the Waikato Chiefs in Super Rugby.
He said he was out for breakfast with his partner and some of his teammates from provincial side Bay of Plenty when Robertson called to confirm his selection.
"I got an unknown-number call. I guess I thought if there was a day to answer those it was probably (that day) and he just said congratulations," said Carter.
"I honestly can't really remember what else he said after that. I was pretty emotional and pretty stoked to get a phone call like that.
"All the boys were pretty pumped but I was still in a bit of a shock."Â
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