McLaren CEO Zak Brown has confirmed that Sainz has signed a multi-year deal with the team.

"We've been assessing him for some time now and rate him very highly among the next generation of young talent emerging through the ranks in Formula 1," Brown said.

For Sainz, the move from manufacturer-team Renault to the struggling McLaren represents probably the best of a shrinking range of options.

He had effectively been squeezed out of Renault by its recent shock signing of Daniel Ricciardo and the retaining of Nico Hulkenburg for 2018.

But during his time with Renault, Sainz was a contracted Red Bull driver on loan to the French team. News of Sainz’s move to McLaren suggests that Red Bull has chosen not to take up its option on the Spaniard to become Max Verstappen's team-mate by filling the Red Bull Racing seat vacated by Daniel Ricciardo.

Sainz and Verstappen had been team-mates at the junior Red Bull F1 team, Toro Rosso, before Verstappen's 2016 elevation to Red Bull Racing.

With Sainz now out of the immediate Red Bull picture, current Toro Rosso driver Pierre Gasly looms as the favourite to become Verstappen’s 2019 team-mate.

"I'm delighted to finally be able to confirm that I'll be a McLaren driver from the 2019 season,” Sainz said.

"It's something I've been looking at for a while and I'm very excited about this next chapter in my career."

Sainz's team-mate remains unconfirmed, McLaren having the option of retaining current driver Stoffel Vandoorne or taking on reserve driver Lando Norris. Current Force India driver Esteban Ocon is also linked with the team.