The Japanese driver is a two-time winner of IndyCar’s flagship race, triumphing on the latter of those occasions with RLLR in 2020.
He has since spent the 2022 season at Dale Coyne Racing and undertook an oval-only campaign with Chip Ganassi Racing in 2023.
Sato will drive the #75 Honda this May.
“I’m absolutely thrilled to make my return to the 108th Indy 500 with Rahal Letterman Lanigan Racing,” said the 47-year-old.
“A heartfelt thank you to Bobby [Rahal], Mike [Lanigan], and David [Letterman] and the entire organisation for this incredible opportunity.
“Gratitude overflows as I am driving the #75 entry with primary sponsorship from Amada.
“My journey with RLL spans over a decade marked by shared successes and rejoining the team fills me with immense excitement.
“Here’s to reconnecting with familiar faces and forging new alliances. I just can’t wait to get to work.”
Sato will join full-timers Graham Rahal, Christian Lundgaard, and Pietro Fittipaldi in the expanded RLL line-up for the Indy 500.
Co-owner Bobby Rahal said, “We’re very pleased to welcome back Takuma to the team.
“We obviously had a great deal of success together and as I’ve said many times, Takuma’s spirit is something that motivates not only me and the entire team, but also his fans.
“We’re looking forward to his contributions and having a successful Indy 500.”
Lanigan added, “It’s exciting to have Takuma return to the team for the Indianapolis 500.
“As he has shown, he knows how to win at Indianapolis Motor Speedway and his experience will add value to our overall programme.”
Practice for the 2024 Indy 500 kicks off on Tuesday, May 14 (local time).