European Formula 3 champion Lando Norris will be McLaren's test and reserve driver for the 2018 Formula 1 season.
The 2016 McLaren Autosport BRDC Award winner got his first taste of contemporary F1 machinery when he tested for McLaren in Hungary in the summer.
As part of his 2018 role, Norris will attend races as well as playing an active role in on-track testing and in the simulator.
McLaren said he is "currently assessing the opportunities and budget required for a full single-seater racing campaign" next year in addition to the F1 role.
Norris said: "The last 12 months have been an incredible journey for me - I've enjoyed every single minute - and this is just an amazing way to bring the year to an end.
"I'm really looking forward to helping the team, starting next week with the tyre test at Interlagos and I will work harder than ever to learn and develop across the next year.
"I have two excellent teachers in Fernando [Alonso] and Stoffel [Vandoorne], and I will do my best to help with the team's efforts to get back to the front.
"I'm still working hard to finalise my own racing programme for 2018 - we're close on a number of different fronts, but not quite there yet."
He added his own racing programme "will be either Super Formula or Formula 2" and that he hopes to be able to announce something "shortly".
McLaren racing director Eric Boullier said: "Lando is somebody who arrives with a very high level of ability, ambition and application.
"It is our job to develop and fine-tune his focus as we increase his understanding of how a Formula 1 team operates and how a modern grand prix car works.
"There will be plenty of opportunity to observe, learn and participate throughout 2018, and we want to make sure Lando is fully prepared, if needed, to step into Fernando or Stoffel's shoes at a moment's notice."
Jenson Button acted as stand-in for McLaren this year, replacing Alonso for the Monaco Grand Prix when the Spaniard competed in the Indianapolis 500.
McLaren executive director Zak Brown added: "He is undoubtedly carving himself a reputation as one of the very best up-and-coming single-seater drivers in the world.
"His summer test for McLaren was also remarkably impressive, and was further proof that he is ready to step up and take on a role of this size, scope and responsibility.
"At McLaren, we are all extremely keen to help him achieve his goal of racing in Formula 1."