Paddy Lowe has been given an early release by McLaren and will join Mercedes next month in a senior management role rather than waiting until 2014.
The former McLaren technical director had originally only been expected to join Mercedes when his old contract ran out at the end of the year. However, an agreement was reached between the two teams for him to make the switch much earlier than originally anticipated. He will start work for Mercedes on June 3.
Lowe is to join in the role of Executive Director (Technical) and will work closely with team principal Ross Brawn and Mercedes motorsport boss Toto Wolff who is also Executive Director (Business).
Lowe said about his move: "I am excited to become part of a highly talented and capable technical organization. The team has already produced probably the fastest car of the 2013 season while the technical challenges of the new regulations for 2014 will give us the opportunity to maximize the synergies available to a works manufacturer.
"That is a challenge I am relishing. I have worked closely with Mercedes-Benz for almost 20 years and deeply admire the company's phenomenal commitment to Formula 1. I look forward to much success together in the years ahead."
Brawn, who played a part in discussions to bring Lowe to Mercedes, added: "I am delighted to welcome Paddy to the team and to begin working together. He has an excellent record of success in the sport and would be an asset to any of our rivals in the pitlane.
"It is no secret that every team is facing a significant balancing act between this year and next. But it is perhaps less obvious that we will also see major changes for the 2015 and 2016 seasons, as development progresses with the new generation of car design and power unit.
"To deliver in these circumstances, a successful team needs strength in depth. Paddy's arrival will further strengthen our organization and puts us in a strong position for the future."
Lowe is viewed as Brawn's long-term successor as team principal, although no time frame has yet been set for when a handover will take place.