Ferrari and Honda have signed up for the Intercontinental GT Challenge ahead of this weekend's series-opening Bathurst 12 Hour, bringing the number of manufacturers registered for the series to eight.
Honda and Ferrari will now be able to score drivers' and manufacturers' points in the five-round GT3 endurance series, which incorporates the Spa 24 Hours in July and the revived Kyalami 9 Hours fixture in November.
They join Audi, Mercedes, Bentley, Porsche and BMW, as well as Nissan, which announced its participation on Monday.
Two Ferrari 488 GTEs have been registered for points in the Bathurst event on Sunday: the HubAuto entry driven by Nick Foster, Tim Slade and Nick Percat; and the AF Corse-run Spirit of Race entry shared by World Endurance Championship regulars Pedro Lamy, Mathias Lauda and Paul Dalla Lana.
Honda is not taking part in the Bathurst series opener and will join the IGTC for the California 8 Hours at Laguna on March 30.
Nissan is represented by a pair of GT-R NISMO GT3s entered by 2015 Le Mans 24 Hours LMP2 class winner KCMG.
IGTC boss Stephane Ratel said: "The addition of seventh and eighth full-season manufacturers, and especially those of Ferrari and Honda's standing, underlines the growing significance of the IGTC on the world stage.
"I am delighted that Ferrari and Honda have committed to the 2019 championship and cannot wait to see how they compare against the likes of Audi, Bentley, BMW, Mercedes-AMG, Nissan and Porsche.
"Not since the days of the FIA GT1 World Championship [in 2010-12] has GT racing enjoyed such a high-profile global platform."
Carmakers can nominate four cars at each IGTC round.
The best two finishers score manufacturers' points, while all drivers in registered cars accrue points towards their championship.
A total of 20 of the 28 GT3 cars on the grid at Bathurst are now registered to score in the IGTC.