Hillmorton takes its name from Hill Morton Farm, the property of John Twigger, who settled in the area in 1863.

[4] Land from the subdivision of this farm was advertised for sale in a local newspaper in 1879 as being "part of Twigger's property known as Hillmorton".

[5] At the same time as Twigger settled the area, 1863 also saw the opening of the Sunnyside Hospital, Christchurch's first mental asylum.

The buildings were constructed in a gothic style by architect John Campbell, and represented a shift in the approach to mental illness in the region.

Where previously those with mental illnesses were held at Lyttelton Gaol,[6] the hospital was founded on the principles of moral management, providing a more supportive environment for patients.

The final buildings of the former Sunnyside Hospital were demolished in April 2007 to make way for additional housing, a move which was met with protest due to the architectural and cultural significance of the structures.

[8] Hillmorton Hospital continues to act as a dedicated mental health facility for the city from nearby to the original Sunnyside location.