The place name element Lis, along with ancient privileges accorded the town, indicates that the settlement was once a high status 'court'. A Norman castle was built here after the Conquest, which eventually fell into disuse in the later Middle Ages. By 1538 when visited by John Leland only a few insignificant remains were to be seen. Sir Richard Carew writing in 1602 concurred;
||Of later times, the Castle serued the Earle of Cornwall for one of his houses; but now, that later is worm-eaten out of date and vse. Coynages, Fayres, and markets, (as vitall spirits in a decayed bodie) keepe the inner partes of the towne aliue, while the ruyned skirtes accuse the iniurie of time, and the neglect of industrie.
Liskeard was one of the 17 Antiqua maneria of the Duchy of Cornwall. The market charter was granted by Richard, Earl of Cornwall (brother of Henry III) in 1240. Since then, it has been an important centre for agriculture. The seal of the borough of Liskeard was Ar. a fleur-de-lis and perched thereon and respecting each other two birds in chief two annulets and in flank two feathers.
When Wilkie Collins wrote of his visit to the town in his Rambles Beyond Railways he had a low opinion of it: "that abomination of desolation, a large agricultural country town". The town went through a period of economic prosperity during the pre-20th century boom in tin mining, becoming a key centre in the industry as a location for a stannary and coinage.