The Discovery Series I was unveiled at the 1989 Frankfurt Motor Show, going on sale in the United Kingdom in October that year,[3] after the vehicle had been developed under the internal code-name "Project Jay".[1] The new model was based on the more upmarket Range Rover, using the same chassis, suspension and 4WD-system,[3] and a derivative body design – with the four-door using much of the more expensive Range Rover's body structure. However, with smaller engines available, just two short side doors[4]at introduction, and other cost-reductions, the new Discovery was priced more affordably, for a larger, more middle-class market segment, intended to counter the Japanese competition at the time.

The Discovery was Land Rover's first model that was positioned as a family car, designed to be both fully off-road capable and suitable as a daily driver for any family, even offering more luggage space and optionally more seats than the Range Rover. The Mark I Discovery remains the only model offered as a three-door, and was the only one available with a four-cylinder petrol engine until 2017.