Pagenaud has been forced onto the sidelines ever since a heavy crash in practice for the Mid-Ohio round in July, triggered by an apparent brake failure, left him with post-concussion symptoms and curtailed his campaign.
A host of drivers have filled in for the 2019 Indianapolis 500 winner, with former Ed Carpenter Racing driver Conor Daly, MSR's IMSA champion Tom Blomqvist and Indy NXT champion Linus Lundqvist each taking turns at the wheel.
Lundqvist has since signed for Chip Ganassi Racing, while Blomqvist will take over the sister MSR car full-time as Helio Castroneves moves into an Indy-only programme with a third entry.
With Pagenaud's future in question, MSR has turned to Rosenqvist who has signed a multi-year agreement.
“I’m super excited to start the next chapter of my IndyCar career together with MSR,” said Rosenqvist. “This will be a great opportunity for myself and MSR to elevate and get to the next level together.
“I’m also pretty excited to get to work with my old friend Tom again. I’m ready to start working together and getting the next season started.”
The Swede, a winner at Road America for Ganassi in 2020, currently sits 12th in the points after notching a second podium of the season at Portland last weekend.
MSR team boss Mike Shank said: “We’re very excited to have our 2024 IndyCar plans finalised and to welcome Felix to the team.
“Felix has been someone that has been on our radar for quite some time now and everything lined up this year to work something out with him.
“It’s no secret that we’ve had a difficult season, with some things out of our control and some things in our control. I think we are all looking forward to resetting completely, starting over and getting to work.
“I think Tom and Felix will work great together and really feed off of each other.
“We will also have Helio with us at every race to provide his feedback and advice which will be an added bonus, so I think we’re in for a solid year ahead.”
Reflecting on his departure from the squad, Pagenaud released a statement on social media.
“I would like to wish MSR all the best and thank Mike Shank, Jim Meyer, and the whole team for the valuable experiences I have gathered through the last two years,” the Frenchman said.
“I wish we could have achieved more together over the last two seasons and win races but we could not make it happen.
“For now my goal is to fully focus on myself and recuperating. It is a slow process and I continue to work with the doctors and do what it necessary to get my health back to 100%.”
Rosenqvist’s place at Arrow McLaren is expected to be filled by David Malukas. The Dale Coyne Racing driver entered the frame once it became apparent that two-time champion Alex Palou had decided to stay at Chip Ganassi Racing.
