The series launched in 2006 sharing its format with the Spanish GT Championship, with two 200-kilometre races per weekend. Three of the first six rounds were joint events with that national series. In 2007 the format was adjusted: the first race, branded the Pro-Am, extended to around 200 kilometres, while the second race — the GT Open — ran to approximately 150 kilometres, with the exception of a single 300-kilometre Barcelona event. Early seasons also featured rounds on the support bill of the World Touring Car Championship.
The current format runs one 70-minute race and one 60-minute race per round. Supporting series have included the Euroformula Open Championship (formerly Spanish F3 Open), GT Cup Open Europe, TCR Europe, and the Alpine Elf Europa Cup.
In the founding season the field was split into GTA and GTB categories. GTA was aligned with the FIA GT2 class, also permitting non-homologated cars built to GT2 technical regulations; the dominant machinery included Ferrari F430 GTs and Porsche 911 GT3-RSRs alongside non-homologated entrants such as the Mosler MT900R and SEAT Cupra GT. GTB was populated by cars drawn from manufacturer cup programmes — Ferrari F430 Challenge, Porsche 911 GT3 Cup, Marcos Mantis. A GTS class was also created for FIA GT3 machinery, primarily Dodge Viper Competition Coupes and Lamborghini Gallardo GT3s.
From 2015, the International GT Open transitioned to an all-GT3 grid, retiring the earlier multi-class structure. Two current sub-categories apply: the Am category, reserved for drivers holding the FIA Bronze driver designation, and Pro-Am, requiring one Bronze driver with no restriction on the co-driver. Overall classification covers all remaining entries, with only a ban on all-Platinum driver pairings as a restriction.
The series has visited circuits across Spain, Belgium, France, Britain, Germany, Austria, Portugal, Hungary, and Italy over the course of its history. Long-standing fixtures include Circuit de Barcelona-Catalunya, Circuit de Spa-Francorchamps, Circuit Paul Ricard, Monza Circuit, and the Algarve International Circuit. Earlier rounds featured venues such as Istanbul Park, Brands Hatch, Donington Park, Vallelunga, Nürburgring, Silverstone, and the Valencia Street Circuit. The Hockenheimring returned to the calendar in 2019 and again from 2024, while Misano World Circuit is scheduled to appear from 2026.
The International GT Open has served as an accessible proving ground for GT3 competitors outside the major FIA-sanctioned championships. Its Pro-Am structure and broad circuit variety have made it a popular platform for gentleman drivers partnering professionals across hardware from the full spectrum of GT3 manufacturers, including Ferrari, Porsche, Lamborghini, Audi, BMW, Mercedes-AMG, and Aston Martin. By maintaining a consistent European footprint and a relatively open regulatory approach during its early years, the series helped nurture the growth of GT3-class racing that became the dominant global format across the following decade.