London Electric Cars (LEC) uses pre-owned Nissan Leaf batteries and motors as the basis of its conversion, with modifications that reduce costs and environmental impact.
The standard conversion includes a 20kWh battery, but customers can install a higher-output motor and upgraded batteries at an additional cost.
If a customer doesn't already own a classic Mini for conversion, the company will source a donor car for a premium.
"As a classic car enthusiast and advocate for affordable and sustainable electric vehicle conversions, it made sense for us to focus on the original Mini," said LEC founder Matthew Quitter.
"With this EV conversion, we wanted the classic Mini to be an affordable yet useful option for city dwellers, not just in our hometown of London but all over the world, to tackle traffic and help put a stop to pollution."
The Leaf's mechanics were chosen following "extensive research and analysis" that suggested reusing the Sunderland-built hatchback's infrastructure was "more sustainable than mining and creating materials for an LEC-only powertrain".
LEC also plans to re-use and renew computer hardware and batteries inside traction packs and manufacturing technology to actually produce the Mini conversions.
The Mini joins the Land Rover, Morris Minor and Morris Traveller in the LEC line-up. It's exempt from road tax, the Congestion Charge and the ULEZ fee.
Build waiting times currently stand at around six months.