Nineteen-year-old Bennett, a member of Fernando Alonso's driver academy, has been signed to take the place of 2023 European Le Mans Series champion Alex Garcia, who was originally listed alongside Jean-Karl Vernay as the first two drivers for Isotta's assault on the Hypercar class of the WEC with the Tipo 6 Competizione LMH.
The Thai-American driver competed in both Spanish F4 and Formula 4 Brazil last year, scoring a podium finish in the latter series with Oakberry Bassani team.
He is currently taking part in the LMP2 class of the Asian Le Mans Series with Duqueine, the French outfit that has replaced Vector Sport as Isotta's factory team in WEC.
"I am thrilled to announce my partnership with Isotta Duqueine for the highly anticipated World Endurance Championship season in 2024," he said.
"This collaboration carries a profound significance for me as I proudly represent Thailand on the global stage of motorsports.
"Joining forces with Isotta Fraschini and Duqueine Team is a realization of a lifelong dream.
"I am committed to giving my absolute best. Together with Isotta Duqueine, I am confident that we will achieve great things together."
Isotta will have another youngster in its line-up in the form of Canadian Serravalle, who spent the majority of his career in the US competing in the Road to Indy ladder.
After two partial seasons in Indy Lights from 2021-22, he switched to the LMP3 class in IMSA's VP SportsCar Challenge and also made his debut outing in the Daytona 24 Hours at the wheel of a Duqueine M30 - D08.
Serravalle was announced as the third and final driver by Isotta on Wednesday, before it elected to replace Garcia with Bennett on Thursday.
"I feel incredibly honored to compete for Isotta Fraschini and Michelotto Engineering, both with their rich history," said the 21-year-old.
"Being part of the prestigious FIA WEC racing series, particularly in the top-tier LMH hypercar category, is truly surreal. I extend my gratitude to Duqueine and Remstar Management for believing in me and providing this extraordinary opportunity."
Touring car star and one-time Le Mans 24 Hours class winner Vernay will be the only experienced driver in Isotta's line-up following its decision to split with Garcia before the start of the season.
He said: "Being involved in the project since the beginning, it's super exciting for me. I think it's fantastic news taking part in the FIA WEC 2024 season.
"Thank you to Isotta Fraschini and the Michelotto guys since the car is great, and thanks to Duqueine for the support. I can't wait to be in Qatar. Of course, we're having some young guys with Antonio and Carl, but I think. We have a strong line-up.
"It won't be easy because the people we are battling against are super-strong and with a lot of experience, that we don't have, but I'm looking forward to it, and... let's keep pushing!"
