Following Jimmie Johnson’s departure, the car will be run as #11, and Armstrong will team up with New Zealand compatriot and six-time champion Scott Dixon, 2021 champion Alex Palou and 2022 Indy 500 winner Marcus Ericsson for the 12 non-ovals on the 2022 calendar.
The 22-year-old had been in negotiations with Dale Coyne Racing before and after testing for the team impressively at Sebring in October, and was believed to be nearing a deal with Coyne to partner David Malukas full-time in 2023, with Takuma Sato becoming an oval-only third driver.
However, instead Armstrong will take on recent F2 rivals Callum Ilott (Juncos) and 2022 IndyCar Rookie of the Year Christian Lundgaard (Rahal Letterman Lanigan) from the seat of the legendary Ganassi operation, which has taken its drivers to 14 championships since 1996.
“I’m ecstatic to be a part of the IndyCar Series, but especially with Chip Ganassi Racing because it is such an iconic and successful team,” said Armstrong, who scored four wins in three seasons of F2.
“I have an extraordinary opportunity in front of me to learn from people that have been performing at the absolute highest level in this sport.
“As a Kiwi, I’ve always watched Scott Dixon succeed in the championship with this team, so on a personal level this is quite special for me.
"I am a hard worker that looks to improve every single day. With the knowledge and personnel that this team has, I’m very excited to take on this new challenge.”
Mike Hull, Ganassi’s managing director, said: “Marcus driving the #11 car for Chip Ganassi Racing in 2023 is exciting.
"As a 22-year-old, what is in common to others who have climbed into IndyCar with CGR is that at that age he already knows how to win. That's been repeatedly proven at the highest global level."
Who will get to race the #11 in the five oval races including the Indianapolis 500 is now open to conjecture.
While Ryan Hunter-Reay has a development role at Ganassi, thus far the role has been confined to sportscars, and he ran two IMSA endurance races with the team this year.
The 2012 IndyCar champion and 2014 Indy 500 winner might be considered a lock for the ride given his prowess on ovals, but two-time Indy 500 winner Takuma Sato is also understood to be in negotiations for the seat.
This appears to go against the understanding that the Japanese veteran would be running an oval-only programme for Dale Coyne Racing, and could not race for anyone other than DCR should he choose to continue in IndyCar in 2023.
