John Joseph William Molesworth Oxley (1783 – May 26, 1828) is an explorer and surveyor of Australia in the early period of English colonization.

In October 1802, he is engaged in coastal survey work including an expedition to Western Port in 1804-05.

In 1805, Governor King appoints him acting lieutenant in charge of the Buffalo, and in 1806 he commands the Estramina on a trip to Van Diemen's Land.

Next year, he returns to England where, on November 25, he is commissioned lieutenant.

He returns to Sydney in November 1808 to take up an appointment as first lieutenant in HMS Porpoise, having sailed out as agent for the Transport Board in the convict ship Speke, in which he had shipped goods worth £800 as an investment.

He had obtained an order from the Colonial Office for a grant of 600 acres (240 ha) near the Nepean River, but Lieutenant-Governor Paterson granted him 1,000 acres (400 ha).

Oxley has to surrender these in 1810, but Governor Macquarie grants him 600 acres (240 ha) near Camden, which he increases in 1815 to 1,000 acres (400 ha) again.

This he calls Kirkham.

When Paterson allows the deposed Governor Bligh to leave Sydney in Porpoise in March 1809, Oxley is aboard and sails with Bligh to the Derwent.

Next year he writes a lengthy report on the settlements in Van Diemen's Land before sailing for England in Porpoise in May.

In London, he applies for the post of Naval Officer in Sydney, and then, after paying Charles Grimes to resign, according to John Macarthur, he twice seeks that of surveyor-general.

Oxley denies that he had been a partisan of Macarthur when Bligh was deposed, but his letters show that he was on very intimate terms with the rebel leader.

In 1812, he becomes engaged to Elizabeth Macarthur; this is broken off when her father discovers the extent of Oxley's debts.

By this time, through the influence of Macarthur's friend Walter Davidson, Oxley's second application for the surveyor-generalship had been successful.

In 1811, he had retired from the navy, and in May 1812 sails for Sydney in the Minstrel to take up his new duties.