Isack, who only turned 21 in September, has enjoyed an impressive first season with Red Bull’s junior team Racing Bulls, scoring 10 top-10 finishes, including his first podium when he finished third in the Netherlands.
He replaces Japanese driver Yuki Tsunoda who becomes Red Bull’s test and reserve driver.
“After all the hard work I have put in since joining the junior team, it’s such a great reward,” a grateful Hadjar said in a Red Bull statement.
“I’ve had many ups and downs throughout my career and they kept believing and pushing me.
“It’s an awesome move, to work with the best and learn from Max is something I can’t wait for.”
Red Bull will be hoping Hadjar can solve the perennial problem of Verstappen’s partner.
After releasing Sergio Perez at the end of last season, Red Bull began 2025 with Liam Lawson at the wheel but the New Zealander lasted only two races before being supplanted by Tsunoda.
Since then, however, Tsunoda has scored just 33 points in the world championship compared with Verstappen’s 396.
The Japanese driver, who has been with the team since joining the junior programme in 2019, has competed in more than 100 Grand Prix and has yet to make a podium.
He currently sits one place and three points below Lawson in the standings.
“Everyone in the sport would agree it is impossible not to like Yuki, his personality is infectious, and he has become a very special part of the Red Bull family,” said team principal Laurent Mekies.
“On behalf of everyone at Red Bull, I thank him for what he has contributed so far and we know he will provide invaluable support to the 2026 projects moving forwards.”
Lawson will continue with Racing Bulls in 2026 when he will be partnered by Arvid Lindblad, who turned 18 in August and who is currently with the team’s junior programme in Formula 2.
“He (Lindblad) has demonstrated raw speed, maturity and potential, underscoring the team’s long-standing commitment to developing elite young talent,” Racing Bulls said in a statement.
Lindblad, who was born and brought up in England with a Swedish father and an British-Indian mother, was granted an FIA Super Licence aged 17 and recently tested in the first practice at the Mexico City GP.
Driving Verstappen’s car he posted the sixth best time in the session. (AFP)