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.
Source: Autosport