Takuma Sato will move back to Rahal Letterman Lanigan Racing for the 2018 IndyCar season.
Sato has spent the season just past at Andretti Autosport, during which time he won the Indianapolis 500, the first time a Japanese driver has done so.
He finished in the top five on four occasions in 2017 and ended the year a personal best eighth in the series.
However, the delay in Andretti confirming whether it would continue with Honda engines was understood to have led Sato, who has close ties with the manufacturer, searching for another team.
He joins Graham Rahal, who scored a pair of wins at Detroit this year en route to sixth in the series, in an expanded two-car RLL line-up.
Sato previously drove for the team in 2012.
“I’m excited about having Taku back with us,” said team co-owner Bobby Rahal.
“I have such admiration for his spirit and how he approaches everything and was so happy for him when he won the Indy 500 this year.
“The chance to bring him back to the team was too good to pass up.
“He and Graham get along very well and we will have two strong cars that can win any race in 2018.
“I think that will give our team a great chance at being contenders in every race but it’s also going to give each of our drivers a chance to have their best years ever.
“I’m excited about it and even though the 2017 season just concluded, I can’t wait for the 2018 season to start.”
Sato added, “I am extremely happy to be back with Rahal Letterman Lanigan Racing. Bobby, Dave (Letterman) and Mike (Lanigan) have always been very supportive of me.
“The team has been ultra-competitive the past few seasons. I can’t wait to be a part of it in 2018.”
Rahal Letterman Lanigan ran a single car for the majority of the 2017 campaign for Graham Rahal, although it fielded a second entry for Oriol Servia at Indianapolis and Detroit and for rookie Zachary Claman De Melo at the Sonoma finale.
It last ran two cars for a full season in 2013, when James Jakes partnered Rahal.