Archaeological digs at near Ashlawn Road in 2017 found remains of human settlement dating back to the Bronze Age (1000 – 500 BC), as well as numerous finds of occupation from the Roman period, including items of pottery and the remains of pottery or tile kilns.

The village was formed by amalgamation of two settlements: Hull and Morton: The former being the part on high ground, the latter being the part on lower ground to the north where the church of St. John the Baptist stands, and where the canal runs through.

Morton was mentioned in the Domesday Book as land that in 1066 before the invasion of William the Conqueror included portions belonging to Waltheof (of Hillmorton), to Viking (of Barcheston) and to Grimkel and Swein; by 1096 the parish was in the ancient hundred of Marton and had been partitioned between new Tenants-in-chief: the Count of Meulan who enfeuded Waltheof's portion, Richard the Forester who possessed Viking's portion, and Hugh de Grandmesnil who possessed Grimkel and Swein's land.

The market at Hillmorton was originally more important than that of nearby Rugby, but it diminished and was abandoned by the mid 17th century.

The old village green still exists, upon which is the remains of a 14th-century stone market cross which is grade II listed.

[6][8] In 1607 Hillmorton was involved in the Midland Revolt against enclosures, when some 3,000 people gathered at the village to proclaim the manifesto of the 'Diggers of Warwickshire'.

[6] Suburban expansion of Hillmorton westwards began in 1912 when land was sold off west of the village for the construction of the large Paddox housing estate, the development of which continued until the late-1930s.

During the Second World War, Hillmorton was home to a notorious character, Unity Mitford; socialite and close friend of Adolf Hitler, following her return to Britain following a suicide attempt.

[24][25] According to local legend, her presence in the area was a reason why Rugby was not bombed substantially by the Germans during the war.

[26][27] The TV antiques expert David Barby had a business in Hillmorton and lived locally.