The Kiwi has spent the past two seasons competing in the Porsche Michelin Sprint Challenge in Australia driving for Earl Bamber Motorsport.
That stint yielded a best season result of eighth last year.
She has now sealed a move Stateside with a two-year deal with reigning US Carrera Cup champions JDX Racing.
The deal will see Stewart race in Sprint Challenge North America this season before moving up to Carrera Cup North America in 2024.
Stewart will continue to be based in Australia and travel backwards and forwards to the US to compete.
She is currently in the States having tested at Barber Motorsport Park earlier this week, ahead of another test at Sebring next week.
The season then kicks off back at Sebring on the last weekend in March.
"I’m really excited for this new opportunity racing in America," said Stewart.
"JDX has such a great pedigree and had such a strong 2022 Carrera Cup campaign. I’m really looking forward to working with them and I’m confident that I’ll learn a lot.
"It’s also great to have Byers Porsche on board for 2023 and I’m excited to build a relationship with them.
"This will be my first time racing a Porsche 992 Cup Car and to have the chance to race at such iconic circuits such as Sebring, Circuit of the Americas and the Indy road course is a dream come true.
"We’ve had a successful first test at Barber Motorsport Park so I’m excited to see what we can do this year.”
JDX Racing co-owner was impressed with Stewart's maiden test with the team.
“We are very excited about our programme with Madeline," he said.
"She is very focused and serious about her goals in motorsport, and we intend to give her all the tools she needs to achieve those goals.
"Sprint Challenge is quickly becoming a proving ground for young drivers on their way to Carrera Cup, and we think this programme is ideal preparation for our planned 2024 campaign in the ultra-competitive Carrera Cup North America championship.
"We have just completed our first test at Barber, and Madeline did an exceptional job in her first outing in the 992 Cup Car.
"I want to thank Madeline and her sponsors for having the confidence in JDX Racing to guide her on her journey. We’re all in!”
