Running a solo practice from her home between 1946 and 1981, she designed dozens of buildings and renovations, mostly residential, on Sydney's North Shore.

[2] She set up a solo practice in 1946 at her own home in Warrawee, since she felt that women architects were unwelcome in large firms.

[1] Initially, she accepted commissions from friends, and through word-of-mouth recommendations she received enough projects to keep her in full-time work.

[1] Cullis–Hill worked mainly on Sydney's North Shore in the suburbs of Warrawee and Wahroonga, but she also designed residential renovations and houses in East Killara, Hunters Hill, Kenthurst, Pymble and Turramurra.

[3] Her design for the Wahroonga Nursery School was shortlisted for the Australian Institute of Architects' Sulman Award in 1956.