The Ford squad had previously declared its intention to opt for a young driver line-up for next year after 2019 world champion Ott Tanak elected to rejoin Hyundai for 2024.
Fourmaux emerged as a likely candidate to fill the void after M-Sport offered the Frenchman an outing in a Puma Rally1 at last month's Japan season finale in November as a reward for a series of strong showings driving for the team in WRC2, and a run to this year's British Rally Championship title.
Fourmaux and co-driver Alex Coria will now return to Rally1 on a full-time basis next year for what will be a second season driving a Puma Rally1 after a challenging 2022 campaign.
"I'm very happy to be back in Rally1 for 2024," said Fourmaux.
"Achieving this drive was the main goal of the 2023 season and I'm thrilled to return for a full season in the Puma next year.
"I'm grateful to M-Sport, Ford and Red Bull for having the confidence and trust in me to give me another year at the top level and allow me to show my capabilities.
"I've enjoyed being part of the development of the Fiesta Rally2 in 2023, and I think this will help me for the upcoming season with the Rally1 car.
"It will be a very interesting season for everybody, especially with the new regulations and points system.
"We've got a proper plan to work hard and deliver the best results we can, to support the team and get it back to where it deserves to be.
"I'm also very proud to be the only French driver competing the full season at the top level of WRC."
The 28-year-old will be joined by Munster, who made his Rally1 debut with M-Sport this season.
Munster and co-driver Louis Louka started the year competing in M-Sport's Rally2 Ford Fiesta before taking over Jourdan Serderidis' Puma for rounds in Chile and Central Europe, where they impressed the team.
The 24-year-old Munster showed strong pace to finish seventh in tricky conditions at the Central European Rally.
"Driving almost the full season in WRC2 in 2023 has been a big positive, it's the first time I had the chance to do nearly all the WRC events and get the mileage," said Munster.
"The two drives in the Puma have helped me a lot with getting prepared for the Rally1 drive in 2024.
"Working within the M-Sport team has also been incredibly useful, you see the WRC2 and Rally1 team all within the same structure, so it's good preparation for Rally1 to feel familiar and at home.
"I'm eager to start in Monte-Carlo, and the goal for 2024 will be first to get some good results and increase the pace rally after rally, try not to make any mistakes and just get all the experience.
"We're driving against world champions, so it will be a big challenge but I'm really looking forward to it."
M-Sport team principal Richard Millener is confident his young charges can achieve solid results next season, which begins in Monte Carlo from 25-28 January.
"Developing and helping young talent prove themselves is an exciting way to tackle a WRC season, and with several of the top drivers not competing across the full championship we have opportunities to put in some strong and surprising performances," said Millener.
"We still have all the ingredients to deliver results and the team is motivated to start again in a few weeks' time with an almost blank paper on what we can achieve."
Newly crowned WRC2 champion Andreas Mikkelsen had been among M-Sport's targets, the Norwegian telling Autosport that he had an offer to join the British squad for 2024 before electing to take up a part-time drive with Hyundai piloting the third i20 N.
Rally2 drivers Emil Lindholm and Oliver Solberg were also linked to a drive at M-Sport for next year. Solberg has since announced plans to remain in WRC2 after inking a new deal with Skoda, while Lindholm is yet to reveal his programme for next year.
Pierre-Louis Loubet, who piloted M-Sport's second Puma Rally1 this season, has been linked to a move back to Rally2 driving a new Toyota GR Yaris Rally2.
M-Sport will unveil its 2024 Puma Rally1 at the Autosport International show on 12 January.
WRC 2024 Rally1 driver line-up
Toyota – Elfyn Evans, Takamoto Katsuta, Kalle Rovanpera*, Sebastien Ogier*
Hyundai – Thierry Neuville, Ott Tanak, Esapekka Lappi*, Andreas Mikkelsen*, Dani Sordo*
M-Sport-Ford – Adrien Fourmaux, Gregoire Munster
*Partial campaign
