By 1978, Ford Europe was working on a new mid-range model to replace the Cortina/Taunus in the early 1980s. Although still popular with buyers, the outgoing Cortina/Taunus was essentially a 12-year old design by the time of the Sierra's launch; despite the TC2/Mk 4 shape launching in 1976, and the mildly reworked TC3/Mk 5 three years later, both were merely a reskinned version of the 1970 TC/Mk 3 with few major mechanical changes in that time. Ford's future model policy and styling direction had already been shown with the Escort III two years earlier, in that its conventionally styled saloons of the 1970s would be replaced by hatchbacks with advanced aerodynamic styling

Initially there was resistance from potential buyers of the 'jelly mould' body design, it was later in the Sierra's life that the styling began to pay off; ten years after its introduction, the Sierra's styling was not nearly as outdated as its contemporaries. The most notable changes came at the autumn of 1987, with a major facelift and the addition of a 4-door saloon (UK: Sapphire). As other manufacturers adopted similar aerodynamic styling, the Sierra looked more normal. At its peak, it was Britain's second best selling car in 1983, 1988 and 1989, and was still Britain's fifth best selling car in 1992.

The sporting model XR4i utilized the 2.8 engine with mechanical fuel injection (Bosch K Jetronic) coupled to rear-wheel drive (1983-1985) and to four-wheel-drive as XR4x4 (1985-1987). There were visual differences and alterations between the XR4i and XR4x4, such as coloured bumpers, the removal of the 'bi-plane' rear wing and alloy wheels as seen on the Ford Escort RS Turbo Series 1.

The Cosworth model was powered by a turbocharged 16-valve 4-cylinder engine known as the 'YB' which was based on the Ford Pinto block. The Ford Sierra RS Cosworth was introduced in 1986 as a three-door hatchback, with a 2-litre DOHC turbo engine producing 204 PS (150 kW; 201 hp) and a top speed of 150 mph - a speed normally found only in cars from prestige brands like Ferrari and Porsche, at much higher prices and without the practicality of the Ford.

The Ford Sierra remained in production until 1993 when it was replaced by the Mondeo.