The Land Rover Defender was introduced in 1983 to replace the earlier Land Rover series, of which only the Range Rover was still in production. The off-road utility vehicle was introduced to the public in two models which were distinguished by the medallions they carried and launched one year apart. These bore the numbers 90 and 110, which referred to the respective wheel bases of the two vehicles. The medallions were discontinued not long after, though the 2007 model still has a space for a medallion above its radiator. In 1991, the name was changed again to the Land Rover Defender in order to distinguish it from the Land Rover Discover.

There was not much design difference between the Land Rover Defender 90 and the 110 and the earlier incarnations of the Series III Land Rover, though there were three marked changes: a full-length hood over the engine, an updated front grill and wheel arch extensions that were better suited to the suited to wider axles necessary to off-road sport utility vehicles.

Most of the updating on the Defender was internal. The part-time 4-wheel drive in use by Land Rover since 1949 was dropped, as it had never been as popular as Land Rover would have wished. Other changes included a more comfortable and modern interior, a taller windscreen that was one continuous piece of glass, more comfortable coil springs, more power in the updated engine and permanent four-wheel drive.

In 1990, Land Rover took a bold step as far as increasing its customer base by marketing the Land Rover Defender as a personal sport utility vehicle rather than the heavy-use commercial vehicle it been marketed as. Wind-up windows, more luxurious interiors, more comfortable seats and options such as radio/CD players attracted more casual sport-utility vehicle users.

These innovations were joined by a radical change in the Defender engine's breather system, which incorporated an oil separator, which filtered oil from the air in the system. This 200Tdi allowed the Defender to remain steady at high speeds and still pull heavy loads. These changes helped the Defender to become one of the bestselling sports-utility vehicles, while it's power and economy was sought after for use as ambulances and fire trucks.