It is found most often at less than 150 metres above sea level (ASL)[2] on volcanic soils in subtropical rainforest.

[3] It grows often by creeks, or on dry rocky scree slopes, and in disturbed forest and rainforest margins.

A member of the ancient Gondwana family Atherospermataceae, the Illawarra socketwood is in danger of extinction.

Formerly considered the southernmost population of Daphnandra micrantha, the Australian socketwood, it has been recognised as a separate species.

[4] The term 'socketwood' is from the related species Daphnandra apatela, a feature of which is the larger branchlets meeting the main trunk in what resembles a ball-and-socket joint.

Daphnandra johnsonii is a small to medium-sized tree, growing to around 20 metres tall, a stem diameter of 30 cm, with a broad, shady crown.

The lateral veins of the Illawarra socketwood are sharply angled at around 40 degrees in relation to the midrib of the leaf.

Leaves of common sassafras are more aromatic, usually less coarsely toothed, and the midrib is sunken on the upper surface.

The flowers are white with pinkish red margins, forming on panicles or racemes, 3 to 8 cm long.

[4] Most of the 41 sites[5] are under immediate threat from clearing for agriculture, urban expansion, feral animals, weeds, inappropriate use of fire and herbicide, quarrying, and road construction.