Mercedes-AMG presented the AMG GT3 at the 2015 Geneva Motor Show as the racing variant of the newly launched AMG GT family. Development emphasised a significant reduction in vehicle weight, with the car constructed largely from carbon-fibre-reinforced polymer to bring it under 1,300 kg in compliance with FIA GT3 regulations. Rather than using the 4.0-litre twin-turbocharged V8 M178 engine from the road car, the engineering team carried over the naturally aspirated 6.2-litre V8 M159 engine previously used in the SLS AMG GT3, citing the engine's proven reliability and user-friendly characteristics as the primary reasons for its retention.
The car featured an updated aerodynamic package with a "Panamericana" grille design that later became an identifying element of AMG's road car range, including the GT R. The front splitter and rear wing were designed for faster on-track adjustments by technicians.
The AMG GT3 used the same M159 6,208 cc naturally aspirated V8 engine as its predecessor, the SLS AMG GT3. The car weighed under 1,300 kg to satisfy FIA GT3 class requirements. A six-speed sequential racing transmission was fitted, and the safety cell incorporated current FIA-mandated rollover and fire suppression systems. The car included an AMG Ride Control-based racing suspension setup with broad adjustability for teams operating across a range of circuits.
For the 2020 season an updated variant, the AMG GT3 Evo, was introduced. The Evo brought an automatic data logger and analysis system, an automatic engine start function when the car was lowered from its in-built air jacks, and revised brake and traction control systems. The front splitter and rear wing were further refined for quicker adjustment, and the bodywork was restyled with new headlamps and a revised grille offering improved radiator protection.
The AMG GT3 made its competitive debut in the 2016 season. In Europe, teams including AKKA ASP, Black Falcon, HTP Motorsport, and Zakspeed entered the car in the Blancpain Endurance Series, while Zakspeed also competed in the ADAC GT Masters. A standout result came at the 2016 24 Hours of Nürburgring, where AMG GT3 entries claimed positions first, second, third, fourth, and sixth overall.
In Super GT's GT300 class, several established Japanese teams switched from the SLS AMG GT3 to the new AMG GT3 for 2016, including Good Smile Racing with Team UKYO, the number 11 GAINER team, LEON Racing, and Rn-sports.
In Australian GT, New Zealand driver Craig Baird gave the AMG GT3 its first race win anywhere when he won race one of round two of the 2016 Australian GT Championship at the Melbourne Grand Prix Circuit on 17 March 2016, held as a support event to the Australian Grand Prix.
In North America, Riley Technologies entered two customer AMG GT3s in the 2017 IMSA SportsCar Championship GTD class. One car finished third in class at the 2017 24 Hours of Daytona before going on to win the GTD class at the 2017 12 Hours of Sebring. By June 2019, a total of 130 GT3 cars had been sold worldwide.
The Mercedes-AMG GT3 established a strong customer racing record across multiple continents and series from its 2016 introduction. Its longevity — with the Evo update extending the car's competitiveness through the early 2020s — reflected the decision to retain the proven naturally aspirated M159 engine. The car's eligibility for the FIA World Endurance Championship's LM GT3 class from 2025 marked Mercedes-AMG's return to the 24 Hours of Le Mans for the first time since 1999. A second-generation AMG GT3 based on the C192 platform was revealed in March 2026 for a planned customer debut in 2027.