Andretti confirmed the deal on Wednesday, which means the 2022 Indianapolis 500 winner will join Colton Herta and Kyle Kirkwood next season.
It also means that current Andretti driver Grosjean will now face a battle to retain his place at the team, with Dale Coyne Racing’s David Malukas strongly tipped to take its fourth car in 2024.
Fellow F1 refugee Ericsson has won four IndyCar races so far but fell out with team owner Chip Ganassi over the fact he wasn’t being paid like its other drivers – including six-time champion Scott Dixon and the recently-retained Alex Palou.
He said of his new deal: “I’m very happy and proud to be joining Andretti Autosport next season. Andretti is one of the most legendary names in motorsports, so it is definitely a dream come true for me to join this team.
“I want to thank Michael and Dan [Towriss, team co-owner] for putting their trust in me and I can’t wait to get to know everyone in the organisation. It’s a very exciting new chapter in my career and I’m really looking forward to getting to work achieving our goals together.
“Exciting times are ahead and I’m thankful for this opportunity.”
A team statement didn’t reveal which of Andretti’s cars Ericsson will drive or which sponsor he will have, with Grosjean’s spot at the #28 DHL-funded car thought to be a potential home for him.
Team boss Michael Andretti said: “Like everyone else, we have paid close attention to Marcus’ success in IndyCar and have been impressed with how quickly he proved that he belonged with the frontrunners in what is arguably the most competitive IndyCar field ever.
“It’s no secret that we want to win races and championships and to do that we need drivers like Marcus who have that natural talent and determined drive.
“We are excited for the winning mindset that Marcus brings to the table and I’m eager to see what next season has in store for us.”
Grosjean’s second season with Andretti started well, with two pole positions in the first four races and back-to-back runner-up finishes at Barber and Long Beach. But his form then dipped dramatically, although recovered recently with a strong run at Nashville.
He already has a deal to race for Lamborghini’s new IMSA SportsCar Championship assault in 2024 but his priority is understood to be ensuring he remains in IndyCar. Grosjean is known to have reached out to other teams in this regard.
