The milestone comes in the Oxford facility's 15th year of production and parent company BMW's centenary year.
In 2001 the plant was producing around 300 cars a day, and now builds at a rate of around 1000 vehicles per day - meaning the 4500-strong team in Oxford produces one new Mini almost every minute.
A full 80 per cent of all Minis built at the facility are exported to 110 markets around the world.
The JCW Clubman that helped to achieve the milestone is also the first model to combine the company's latest John Cooper Works performance enhancements and Mini's new ALL4 all-wheel drive system.
Powered by a 2.0-litre turbocharged four-cylinder engine, the Mini JCW Clubman produces 170kW of power and 350Nm of torque, claiming a 0-100km/h time of 6.3 seconds.
Drive is sent to all four wheels via a six-speed manual or eight-speed automatic transmission.
The Mini JCW Clubman will arrive in Australia by mid-2017.