Frijns currently races with WRT in the LMP2 class, which will no longer form a part of the WEC from next year when the Belgian outfit steps up to the Hypercar class to run BMW's M Hybrid V8.
The LMDh racer has been fielded in the IMSA SportsCar Championship by the Rahal team this season, while WRT recently commenced testing the car that will mark BMW's return to the WEC for the first time since it campaigned an M8 GTE in the 2018-19 'superseason'.
BMW stated that the 2021 WEC LMP2 champion will be involved in WRT’s test work with the M Hybrid V8, with his race outings to be decided at a later date.
"With his versatility and wealth of experience in prototype racing, Robin Frijns is a fantastic addition to our squad of works drivers," said BMW head of motorsport Andreas Roos.
"He will initially be involved in the test programme with the BMW M Hybrid V8 for WEC. He knows the team and the race series very well and can certainly make a valuable contribution to a successful preparation for the 2024 season.
"A glance at his previous successes shows that Frijns is also an extremely good GT driver. However, we will make a decision regarding any possible race outings at a later date.
"First of all, we are very pleased to have him with us in the BMW M Motorsport family."
Frijns won the 2018 Bathurst 12 Hours and 2017 Blancpain Sprint Cup title in WRT-run Audis, as well as claiming the 2022 Nurburgring 24 Hours and three DTM victories with the four rings.
He joins fellow ex-Audi racers Rene Rast, Dries Vanthoor, Charles Weerts in representing BMW, whose factory driver ranks have swelled to 22 members following the addition of MotoGP legend Valentino Rossi last season.
Mercedes GT ace Raffaele Marciello has also been linked with joining BMW for 2024, with Lamborghini also in contention for his signature
Frijns, who started his car racing career in Formula BMW, winning the 2010 European crown, said: "It is fantastic to return to BMW M Motorsport after so many years – the place it all started for me in Formula BMW Europe.
"I am looking forward to the new challenges, which will include being part of the test programme for the WEC entry in 2024 with the BMW M Hybrid V8.
"The prospect of driving this car and, in doing so, becoming part of a new golden era of motor racing is great motivation."
It emerged last weekend in London that Frijns would be departing the Abt Cupra Formula E squad after a difficult season in which he missed four races due to a wrist injury incurred in a Mexico opening lap crash.
Pole position in Berlin was the high point as he ended the first season of Gen3 competition with six points.