McLaren and Mercedes have confirmed that the respective parties will renew their partnership from 2021 on a long-term arrangement.
McLaren was powered by Mercedes from 1996 through 2014, winning multiple titles, but the Woking-based team switched to Honda power from 2015.
That long-term partnership came to a close for 2018 as McLaren opted to sever that deal in order to align itself with Renault on a three-year deal.
On Friday it was reported that McLaren was set to return to Mercedes power and on Saturday morning that realignment was duly confirmed.
“This agreement is an important step in our long-term plan to return to success in Formula 1,” said McLaren CEO Zak Brown.
“Mercedes is the benchmark, both as a team and a power unit, so it is natural we would seek to secure a relationship with the company for the next phase of our journey.
“This announcement reflects the confidence of our shareholders and is an important message to our investors, employees, partners and fans that we are committed to returning McLaren to the front of the field.”
Mercedes boss Toto Wolff added: “We are delighted to welcome McLaren back to the Mercedes-Benz racing family with this new power unit supply agreement.
“Although the two brands share a prestigious history, this new agreement is all about looking to the future and beginning a new era of power unit supply for the years ahead.
“McLaren have been putting in place the building blocks of their revival over recent seasons, including impressive performances this season with Renault power.
“We hope that this new long-term agreement marks another milestone for McLaren as they aim to take the fight to the sport's top teams, including our Mercedes works team.”