Fernando Alonso will race in the 2018 Daytona 24 Hours for the United Autosports sportscar team, McLaren have confirmed.
United Autosports are owned by Zak Brown, McLaren's executive director.
McLaren permitted Alonso, who has extended his deal with the team for 2018, to miss the Monaco GP earlier this year to compete at the Indy 500.
The Daytona 24 race will be the two-time F1 world champion's first-ever endurance event and could be a precursor to the Spaniard making his debut in the Le Mans 24 Hours as he chases motorsport's Triple Crown.
Describing his participation as an "exciting and interesting project", Alonso said: "Learning about a completely new racing category, adapting to a different car and to another style of driving and everything that goes with it, is a new challenge for me and I can't wait to test myself again as a driver.
"The Daytona 24 Hours is the most iconic US endurance race and one of the world's great races. Everyone knows it."
Alonso will race alongside Phil Hanson and Lando Norris in the event, which will be held on January 26-27. Norris is a development driver for McLaren and is expected to be the team's third driver next season.
Alonso has previously revealed his ambition to complete F1's Triple Crown - the Indy 500, Le Mans and the Monaco GP.
Although Daytona is not part of that collective, it is widely recognised as one of motorsport's pinnacle races.
"It's not part of the Triple Crown but, as I have always said, my aim is to be a complete driver and this experience will help me in the preparation for any other endurance race I might take part in.
"Before I went to Indy, I had never driven on an oval, now I know what an oval is and how to deal with it. I am excited to go back and race in America. After the great time I had during the month of May for the Indy 500, I am looking forward to taking part in another legendary race that will bring back all those amazing sensations that US fans gave me.
"Also, this race happens at a convenient time, in January, when our F1 season is off and we are mainly working on our physical preparation. It will be good to get behind a wheel again! Thanks to United Autosports for having offered me this opportunity and thanks to McLaren for supporting me in this new exciting adventure."