In March 2015, Mercedes-AMG presented the AMG GT3, a race version of the GT, at the Geneva Motor Show, which employs the M159 6,208 cc (378.8 cu in) V8 naturally aspirated engine also used in the SLS AMG GT3.

It consists largely of carbon-fiber-reinforced polymer to decrease the vehicle's weight to under 1,300 kg (2,866 lb) to comply with FIA regulations for races.

In 2016, AKKA ASP, Black Falcon, HTP Motorsport and Zakspeed compete in the Blancpain Endurance Series. Zakspeed also competes in the ADAC GT Masters. They claimed a 1-2-3-4 and 6 at the 24 Hours Nürburgring.

In the 2016 Super GT GT300 class, the AMG GT3s made their Super GT debut with Goodsmile Racing with Team UKYO, the number 11 GAINER team, LEON Racing, and Rn-sports opting to use the AMG GT3s in favor of the SLS AMG GT3s that they used in the previous season.

Two Mercedes customer teams, R'Qs Motor Sports and Arnage Racing, opted to continue using the SLS AMG GT3s. Both of them would switch to AMG GT3s during the 2018 season, switching from SLS AMG GT3 and Ferrari 488 GT3 respectively.

New Zealand born driver Craig Baird gave the new AMG GT3 its first race win anywhere when he took out race 1 of round 2 of the 2016 Australian GT Championship at the Melbourne Grand Prix Circuit on 17 March 2016. The round was held as a support race to the 2016 Australian Grand Prix.

Riley Technologies entered two customer AMG GT3s in the 2017 IMSA SportsCar Championship GTD class. One of the teams cars finished 3rd in class and 20th outright at the 2017 24 Hours of Daytona before going on to win the GTD class and finish 16th outright in the 2017 12 Hours of Sebring.

A GT4 version of the Mercedes-AMG GT was presented at the 2017 24 Hours of Spa. This customer racing car is based on the GT R road version and it made its debut in the ROWE 6 Stunden ADAC Ruhr-Pokal-Rennen race, the fifth round of the 2017 VLN season.

As of June 2019, a total of 130 GT3 cars were sold.

An updated version of the GT3 was introduced at the 24 Hours of Nürburgring in June 2019 for the 2020 season of the FIA GT3 race. New technologies include an automatic data logger and analysis system, a function to automatically start the engine when the car is lowered from its in-built air jacks along with new brake and traction control systems.

The design was also updated in line with the design of the new design update of the AMG GT road car with the changes being the new headlamps and the grille with the latter providing better protection for the radiator.

The front splitter and rear wing were tweaked in order for faster adjustments. The car uses the same 6.2-litre V8 engine as the previous model rather than the 4.0-litre V8 engine of the road car it's the engineers stating the user friendliness and reliability of the engine as the main factor of its retention.