It is documented from the seventeenth century, and is highly prolific, sometimes producing two lambing seasons per year.

Like the extinct Pink-nosed Somerset, to which it is related, it probably derived from cross-breeding of Merinos imported from Spain with local tan-faced sheep similar to the modern Portland.

[8][3] The Dorset Horn was exported to many countries, among them Australia, South Africa and the United States, where the first arrivals were in the 1860s, and where substantial numbers were imported from about 1880.

From about 1950, this was introduced to the United Kingdom, where it rapidly supplanted the horned variant;[5]: 800  the breed association changed its name in 1981 to the Dorset Horn and Poll Dorset Sheep Breeder's Association, and registers both breeds.

The fleece is thick, with a weight of 2.25 to 3 kg, a staple length of 80–100 mm, and a Bradford count of 54s–58s.