The limited-run model is being produced in 799 examples worldwide and will arrive on roads after Cupra is launched as the standalone performance division of Seat at the upcoming Geneva motor show.
Priced from £34,995, the third iteration of the range-topping hot hatch gets a 306bhp petrol engine, up from the Cupra 300's 296bhp, thanks to sportier engine mapping. New exhausts and a package of aerodynamic improvements will also feature, as well as upgraded Brembo brakes, adaptive suspension with Dynamic Chassis Control, and modified front camber.
The car comes available with an exclusive matte exterior finish, copper detailing and bucket seats distinguishing the car from the standard Cupra. There's also an entirely new instrument cluster.
When the Cupra division is established, the top Leon could soon be joined by several other hot models. Patents for Bolero, Tango and Salsa have all recently been filed by Seat, suggesting that Cupra could use the names of its past sporting concepts for a performance range.
Prior to the new Leon Cupra R, the most powerful model in the Seat range was the 296bhp Leon Cupra 300. That car's output is expected to be at least matched by the upcoming Ateca Cupra, which has been spied numerous times ahead of its official debut.
Seat previously produced a Leon Cupra R between 2002 and 2005, before resurrecting the name in 2010 on the second-generation Leon, with an extra 24bhp over the standard Cupra model.