The Japanese driver's contract will see him line up in the #11 entry which Marcus Armstrong was already signed up to drive on the road courses and street circuits.
Sato has scored six wins in his 13 IndyCar seasons to date, but two of those were the Indianapolis 500, in 2017 with Andretti Autosport and in 2020 with Rahal Letterman Lanigan Racing.
Most recently, he drove for another Honda-powered team in Dale Coyne Racing, with the season ahead being his first as a part-timer.
“First of all, I would like to thank Chip [Ganassi] and Mike [Hull, Managing Director] for helping put this all together,” said the 45-year-old.
“I am extremely excited to join Chip Ganassi Racing for the 2023 season.
“The organisation has been at the top of our sport for decades and needless to say, extremely competitive.
“Focusing on the oval races is a new chapter for me but I'm thrilled to have the ability to race with team members and team-mates that have won the championships and Indianapolis 500 in the past, which is a tremendous advantage.
“I just can't wait to get started.”
Sato's signing means Ganassi boasts Indianapolis 500 winners in three of its cars, given Scott Dixon prevailed in 2008 and Marcus Ericsson last year, while both Dixon and its other driver, Alex Palou, are series winners.
Hull remarked, “What a terrific opportunity to have Takuma Sato drive our #11 Honda IndyCar on the ovals in 2023.
“He is a two-time Indianapolis 500 winner who contributes with the experience of knowing how to win, by matching the strength of his three team-mates, which equals four who race as one.
“Chip Ganassi Racing looks forward to the 107th Running of the Indianapolis 500.”
The Indianapolis-based squad could yet field five cars during the Month of May, with Jimmie Johnson revealing that he is free to drive a Honda-powered car in the 500 despite returning to NASCAR as an owner-driver of a Chevrolet team.
Ironically, Ganassi will compete as the factory team of one of Chevrolet's sister marques from General Motors when it runs Cadillac V-LMDh cars in this year's IMSA SportsCar Championship and World Endurance Championship.
The former begins this weekend with the Roar Before the 24 at Daytona.