On 25 April 1870, she married the Rev. George Frederick Cross and a few weeks later sailed for Australia. She arrived in Melbourne in August and was surprised to find it a well-established city. Her husband was sent to Wangaratta, then to Yackandandah (1872), Ballan (1874), Coleraine (1877), Bendigo (1884) and Beechworth (1885), where they remained until 1893. Her Thirty Years in Australia (1903) describes their experiences in these parishes. She experienced her share of tragedy, including the loss of children to whooping cough and scarlet fever.

In 1875, her first novel, Up the Murray, appeared in the Australasian, but was not published separately. It was not until 1890, with the publication of A Marked Man, that her fame as a writer was established. However, despite regular good reviews, there were many who discounted her because she did not write in the literary tradition of the time, one that was largely non-urban and masculine, that focused on survival against the harsh environment.

In 1893, Cross and her husband moved to their last parish, Williamstown, near Melbourne, and remained there until 1909. Her husband went on the retired clergy list at the end of 1909 with permission to operate in the diocese until 1912. In 1913 they both returned to England, where they stayed until his death on 27 February 1917. Ada returned to Australia later that year, and died in Melbourne on 19 July 1926. She was survived by a daughter and a son, Dr K. Stuart Cross.

The Ada Cambridge Prizes were first awarded in 2005. There are now four such prizes: the Ada Cambridge Biographical Prose Prize, the Ada Cambridge Poetry Prize, the Young Adas Short Story Prize, and the Young Adas Graphic Short Story Prize. These all carry a cash component and winners are announced at the Williamstown Literary Festival each year.