Stoffel Vandoorne will contest the final two races of the 2018/19 FIA World Endurance Championship season with the SMP Racing LMP1 team, replacing Jenson Button at the Le Mans 24 Hours.
Ex-McLaren Formula 1 racer and current HWA Formula E driver Vandoorne will also take Brendon Hartley's seat for next month's Spa 6 Hours prior to the Le Mans season finale in June.
He'll partner Vitaly Petrov and Mikhail Aleshin in SMP's #11 BR Engineering BR1-AER for both races. The line-up for the sister #17 car, comprising Stephane Sarrazin, Sergey Sirotkin and Egor Orudzhev, remains unchanged.
The change stems from Button's withdrawal from what would have been his second outing at Le Mans, partly because of a desire to spend more time with fiancée Brittny Ward and also because of the inability of the privateer LMP1s to challenge the dominant Toyotas.
Button said: "I really enjoyed driving for SMP Racing and was happy to be on the podium with this team, but I decided that now I need to spend more time at home with my fiancée during her pregnancy rather than two weeks at Le Mans.
"The decision has been made easier for me as I feel that the Toyota is currently unbeatable."
SMP originally offered the Le Mans drive to Hartley, but the New Zealander refused because he has another commitment for the French classic, believed to be a reserve role for the Toyota LMP1 team.
Because there is no other opportunity for Vandoorne to test the BR1 prior to Le Mans - he is unavailable for a private SMP test in Spain - Hartley agreed to step aside to allow the Belgian to race at Spa.
"I am very pleased to join SMP Racing and drive the BR1 #11 prototype in my home race in Spa-Francorchamps and in the legendary Le Mans 24 Hours," said Vandoorne.
"The LMP1 cars are really demanding and their performances are very close to Formula 1. Also, it´s great to work alongside such experienced drivers as Vitaly Petrov and Mikhail Aleshin.
"My objective is to contribute to the team's performance and work in collaboration with all drivers to develop the BR1 prototype and to make a good impression."
Vandoorne was previously in line for the seat in the #11 line-up vacated by Button for last month's Sebring 1000 Miles and Spa round due to the Englishman's Super GT commitments with Honda, before the team settled on ex-Toro Rosso F1 driver Hartley as a replacement.
Button contested a further three WEC races last year after retiring from his Le Mans debut with engine problems, taking a best finish of third alongside Petrov and Aleshin at Shanghai.
Button partnered Vandoorne for one race in F1, taking Fernando Alonso's McLaren F1 seat while the Spaniard contested the Indy500 that year.
One other change in the LMP1 line-up for the Spa race is the addition of Paolo Ruberti to the ByKolles squad.
The Italian GT racing veteran will share the ENSO CLM P1/01, which will be making its first outing with a Gibson power unit, with team regulars Oliver Webb and Tom Dillmann.