A successful season in Europe has earned the 18-year-old a coveted spot on the BOE Motorsports team to contest the championship, which features 22 grand prix races across 18 countries.
He is the first full-time Kiwi racer in the MotoGP ranks since the legendary Simon Crafar nearly 25 years ago in 1999.
"It's definitely an honour and doesn't quite feel real to be honest. Coming from a small country like New Zealand, where motorcycle racing is a passion but not a major sport like it is in Europe, it feels really special to achieve this," Buchanan said.
Crafar, who will next year take on the prestigious role of chairman of the FIM MotoGP Stewards Panel, said it was "amazing news".
'It's wonderful for Cormac to reach his personal goal of becoming a fulltime world championship rider, but it's also exciting news for us proud, sport-loving Kiwis," he said.
"Becoming a full time grand prix rider is a rare and special achievement. Cormac has dedicated most of his young life to achieving it and his family have sacrificed more than we will know, but this is only the beginning
"Making it to the world championship is like getting selected for a national team. The hardest test starts now. The highs and lows of brutal competition over the next couple of years will forge Cormac into a new, tougher version of himself. Let's all let him know that we are behind him."
Buchanan was rapt to be taking the next vital step in his racing career.
"My goal for this year was to earn my place in the 2025 Moto3 World Championship and to be able to step up into those elite ranks with a team the calibre of BOE Motorsports is a great privilege.
"It's a crucial stage in my career and one step closer to my ultimate dream, so I'm really excited to get 2025 underway. There are plenty of things I want to tick off as I learn in my rookie year but, most importantly, I want to make sure I'm constantly improving - it's a big step up with lots of challenges like new tracks, a new bike, a new team.
"Those are all things I'm going to have to contend with so the focus will be on fighting for points consistently and making sure I continue to progress as a racer."
Buchanan's evolution in the sport has been swift since his debut race in 2019. He already has six New Zealand championships to his credit and has spent the past four years competing against the world's best young talents in Europe as part of Red Bull MotoGP Rookies Cup and the FIM JuniorGP World Championship.
This year with AGR Racing he has secured two podiums, a pole position and five top-five finishes. With one round remaining in Portugal from 25-27 November, he sits eighth and was still in the hunt for second overall, just 16 points adrift.
