McLaren is developing a new GT3 racer based on its latest 720S sportscar in-house for 2019.
The 720S GT3 built by McLaren Motorsport will replace the 650S developed by the CRS organisation that traded under the McLaren GT name.
McLaren Automotive boss Mike Flewitt said: "It was vital we remained in GT3 - motorsport is part and parcel of what McLaren is and what our customers see as the brand.
"A few years ago we were only talking about Europe, but GT3 is growing around the world, and that suits us down to the ground because we are a global company selling cars in 30 different countries.
"We wanted more and more of the business under our control and we are now at a point where we can take development of the GT3 car under our management."
GT3 founder Stephane Ratel described McLaren's decision to continue in GT3 as "business as usual".
"Of course it is fantastic, but it would have been bigger news if one of our manufacturers decided not to do a new GT3 car," he said.
The plan is for the new GT3 car, which is powered by a development of the four-litre twin-turbo V8 used in the 650S GT3 and the previous MP4-12C GT3, to be unveiled next summer.
That will lead into a development programme over the second half of the season, which will include some racing before the first deliveries to customers begin in December 2018.
Longtime McLaren factory driver Rob Bell has now been contracted by McLaren Motorsport and will lead development of the car.
No price has been announced, but it is predicted to be close to the £330,000, minus taxes, of the 650S.
McLaren Automotive's motorsport arm is expanding to handle the GT3 programme, as well as a number of other projects.
It is currently establishing a new base two miles from the home of the Formula 1 team and the sportscar production line at the McLaren Technology Centre.
McLaren's contract with CRS finishes at the end of this year and no new 650S GT3s will be built, but the company run by Andrew Kirkaldy will be able to continue to provide service support with customers running the cars.
McLaren Automotive is establishing a global network of dealers to service the 720S GT3 and its other racing and track day products.
McLaren has also announced a new one-make championship for a grid of 570S GT4 cars centrally run by the factory.
The Pure McLaren-GT Series is aimed at McLaren owners looking to take their first steps in racing.
McLaren has launched a driver development programme with a two-car assault on the GT4 division of the British GT Championship.