While Horner has been removed from his role, it has not been made clear if he has formally departed the company or if a settlement or severance is in place.
Reigning world champion Max Verstappen thanked Horner on social media.
“From my first race win, to four world championships, we have shared incredible successes. Winning memorable races and breaking countless records,” Verstappen said., external
Englishman Horner will be replaced as team principal and chief executive of Red Bull Racing by Laurent Mekies, who has been promoted from second team Racing Bulls.
The 48-year-old Frenchman had been in the role since the start of the 2024 season and was previously racing director for Ferrari.
Englishman Alan Permane, 58, has been promoted to team principal of Racing Bulls from his position as racing director.
Under Horner, Sebastian Vettel won the drivers’ championship from 2010 to 2013, with Verstappen winning the past four titles.
“We would like to thank Christian Horner for his exceptional work over the last 20 years,” said Oliver Mintzlaff, Red Bull’s chief executive of corporate projects and investments.
“With his tireless commitment, experience, expertise and innovative thinking, he has been instrumental in establishing Red Bull Racing as one of the most successful and attractive teams in Formula 1.
“Thank you for everything, Christian, and you will forever remain an important part of our team history.”
Horner’s dismissal comes amid uncertainty about the future of star driver Verstappen.
The four-time world champion is under contract to Red Bull until 2028 but is being courted by Mercedes to potentially join them for next season.
Red Bull have won only two races this season, with McLaren taking over their position as the team to beat.
Red Bull’s decline began in the middle of last season. While Verstappen won his fourth straight world title, he won only twice in the final 14 races.