The 51-year-old Horner was the longest-serving team principal, having been in the position since Red Bull made its Formula One debut in 2005.
Frenchman Mekies joins from Red Bull’s sister team Racing Bulls. Alan Permane, currently racing director, will be promoted to team principal at Racing Bulls.
“Red Bull has released Christian Horner from his operational duties with effect from today and has appointed Laurent Mekies as CEO of Red Bull Racing,” the Milton Keynes-based team said in a statement.
Red Bull won eight Drivers’ World Championships and six Constructors’ Championships under Horner, but struggled this season with the team sitting fourth with 172 points in the constructors’ standings. They trail leaders McLaren by 288 points.
Red Bull’s four-times Formula One champion Max Verstappen has won two of 12 races and is third in the drivers’ championship.
Horner’s position was questioned, with Verstappen’s father calling last year for him to go after allegations of misconduct were made by a female employee. The Briton denied them and was cleared after an investigation.
“It has been an amazing adventure to contribute to the birth of Racing Bulls together with all our talented people,” Mekies said.
“The spirit of the whole team is incredible, and I strongly believe that this is just the beginning.
“Alan is the perfect man to take over now and continue our path. He knows the team inside out and has always been an important pillar of our early successes.” (Reuters)