Broom, who was born in Paisley, Scotland, graduated in medicine from Glasgow University in 1889. He traveled to Australia in 1892 and in 1897 settled in South Africa where he practiced medicine, often in remote rural communities, until 1928. He also held posts as professor of geology and zoology (1903–10) at Victoria College, now Stellenbosch University, South Africa, and curator of paleontology at the Transvaal Museum, Pretoria from 1934 until his death.

Apart from studies of the embryology of Australian marsupials and monotremes, Broom's major contributions to science have been concerned with the evolutionary origins of mammals, including man. He excavated and studied the fossils of the Karroo beds of the Cape, and in the 1940s discovered numbers of Australopithecine skeletons in Pleistocene age quarries at Sterkfontein, Transvaal. These latter have proved of considerable importance in investigations of man's ancestry and Broom's account of their discovery is given in Finding the Missing Link (1950).