Hornsby Heights lies predominately on the high narrow ridges of the Hornsby Plateau above the eastern side of Galston Gorge and the Berowra Valley National Park which makes up the suburb's rugged and beautiful northern, western and much of its eastern boundaries.

On the southern and southeastern side of the suburb, the boundaries meet with Hornsby and to a lesser extent, Asquith.

The steepness of some of its streets are also a feature, as many have been cut into the surrounding valleys to maximise the available land close to the ridge edges.

The name Hornsby is derived from Convict-turned-Constable Samuel Henry Horne, who took part in the apprehension of bushrangers Dalton and MacNamara on 22 June 1830.

[1] Bird and animal life abound in the suburb, with many species being regular visitors to resident's homes.

As with any bushland suburb, the area is subject to bushfire risk during summer so it has its own Rural Fire Service Brigade located on Galston Road.

The Galston Gorge to Crosslands section of the Great North Walk runs along the western boundary of Hornsby Heights.