Carlos Sainz will replace Jolyon Palmer at Renault in 2018 as part of a loan deal with Red Bull.
In recent weeks Sainz became a key part of the protracted engine negotiations between McLaren, Renault, Honda and Red Bull which was all focused around 2018. McLaren was looking to escape from its Honda deal but needed the Japanese manufacturer to find another partner in F1 in order to make the switch to Renault, which has since been confirmed.
With Red Bull pushing for its junior team to take on Honda power, Renault agreed to free Toro Rosso from its deal one year early on the proviso it could have Sainz in exchange.
It means Sainz will partner Nico Hulkenberg in 2018, confirming the end of Palmer's run at the team. The announcement made no mention of reports Sainz might replace Palmer as early as the Malaysian Grand Prix.
Sainz said it is a proud day to move to one of the grid's manufacturer outfits.
"I'm very happy to be joining Renault Sport Formula One Team," he said. "To be a Formula one driver for a manufacturer team is an honour and I hope to reward Renault's faith in me with my very best performances on track.
"The trajectory of Renault Sport Formula One Team is exciting and I'm proud to join at such an important time in their history. I am looking forward to working with everyone at Enstone and Viry, and driving alongside Nico Hülkenberg. I have worked closely with Renault in Formula One and previously in motorsport, so I know their motivation and capabilities. This is the start of a very exciting new chapter in my career. I would like to say thank you to Red Bull for all their confidence and support and for allowing me to take this opportunity.
"Last but not least, I specially want to thank all the people that work in Toro Rosso. They are a fantastic team of professionals and I wish them the best for the future."
Friday's announcement made it clear Sainz remains part of the Red Bull programme overseen by Helmut Marko, who feels the deal is mutually beneficial to all involved.
"We are happy to have reached an agreement for Carlos to drive for Renault Sport Formula One Team in 2018. He is a tremendous talent and he will benefit from working with a manufacturer team alongside a highly experienced driver.
"This will give Carlos a different challenge and we will be keenly watching his progress there as he remains part of the Red Bull family. This is very good development for both Carlos and Renault Sport Formula One Team and will also allow us to bring a new talent into Formula One."