[1] Knibbs joined the New South Wales Land Survey Department in 1877 and in January 1878 was appointed a licensed surveyor.

In 1889 Knibbs resigned to take up private practice as a surveyor, and in 1890 became lecturer in surveying at the University of Sydney.

Knibbs had begun contributing papers to the Royal Society of New South Wales at an early age, at first on matters arising out of surveying, and then on problems of physics.

Knibbs resigned his directorship of the Institute of Science and Industry in 1926, and lived in retirement until his death of coronary vascular disease[1] at Camberwell, Victoria, a suburb of Melbourne, on 30 March 1929.

In 1913 he published a volume of verse, Voices of the North and Echoes of Hellas, largely translations, carefully written but not important as poetry, and in 1928 appeared a work on population, The Shadow of the World's Future.