Pourchaire will make his IndyCar Series debut behind the wheel of the #6 Chevrolet as Malukas continues to recover from a left wrist injury and surgery following a mountain biking accident over the off-season.
The Frenchman comes into the mix with an impressive CV that includes claiming the 2023 Formula 2 championship, which came courtesy of two wins and 10 podiums with French-based outfit ART Grand Prix.
Beyond currently serving as a test and reserve driver with Sauber in F1, Pourchaire is also competing in Super Formula this year.
Malukas remains sidelined following wrist surgery and, with Callum Ilott unable to continue his cover in the #6 car due to World Endurance Championship commitments, Arrow McLaren has instead turned to Pourchaire.
"This is an amazing opportunity to drive with such a legendary team in a legendary motorsport series like the NTT IndyCar Series," said Pourchaire. "I’ve watched IndyCar since I was a young kid, and the racing is incredible. I was thrilled to get the call from the team.
"I’m grateful that Zak [Brown, McLaren CEO], Gavin [Ward, team principal] and Tony [Kanaan, sporting director] thought of me for this opportunity and for the team at Sauber to allow me to get on track at Long Beach.
"I’m also sorry that the opportunity came as David continues to recover. It’s not going to be an easy task, but I’m ready for it."
Pourchaire also holds the distinction as the youngest driver to win races in both F3 and F2, having made his move into F3 aged just 16.
While Arrow McLaren continues to evaluate the recovery timeline for Malukas, which has extended beyond the original timeline of six weeks, the team has held off from confirming who will drive the following race weekend at Barber Motorsports Park on 26-28 April.
"It’s a shame that David’s recovery is longer than we all originally anticipated," said Ward. "He’s been working with our team trainer very closely with what rehab and strength exercises are possible at this point, and the team’s been doing a great job in the meantime to work together through the changes they’ve had since his injury.
"Theo may be an unexpected driver in the NTT IndyCar Series paddock this season, but we’re excited to see what he can do on the track in Long Beach and are thankful for Sauber in working with us to make it happen. He has a strong resume, especially for his young age, and he’s eager to work with us and put his driving to the test this weekend.”