Sanchez will report directly to team principal Bruno Famin in his new role, and will oversee the new three-pillar technical structure implemented at the Enstone team.
This means that the technical directors of each pillar: Ciaron Pilbeam of performance, Joe Burnell of engineering, and David Wheater of aerodynamics, will all report to Sanchez.
Sanchez left his role at McLaren just one month ago, having joined the Woking team in January, after finding that the performance role that he had been brought in to occupy had changed in almost a year's gardening leave.
McLaren agreed to release the Frenchman to ensure he could find a more senior role, leading to Alpine securing his signature to help instigate a turnaround in fortunes.
“I am delighted to welcome David back to Enstone, where he started his career back in 2005. This is a key appointment to ensure we are optimising everything we do as a team and focusing on the right performance areas," said Famin.
"It is clear that the performance of the car and development path has not moved at a sufficient pace relative to our ambitions as a team. We look forward to welcoming David and working hard together to achieve the ultimate success.”
Sanchez added: “I’m excited by this challenge at Alpine. I’m looking forward to working at Enstone again, the place where I started my Formula 1 career.
"This team has always had so many fantastic people involved and there is clearly so much potential to unlock. We have a big task ahead to improve on-track performance and it is this type of challenge that motivates me.
"I’m very much ready to begin and look forward to working with the Enstone-Viry technical teams again with the sole aim of bringing regular success back to this great team.”
Alpine's switch to a three-pronged technical line-up, taking inspiration from McLaren's set-up, emerged after former technical chief Matt Harman and aerodynamicist Dirk de Beer both left the team following the launch of this year's A524 chassis.
Although the team elected to chase a new design concept with its new car, it emerged in pre-season testing overweight and lacking performance - resulting in poor results among the opening five races.
