Sir John Robertson KCMG (15 October 1816 – 8 May 1891) was a London-born Australian politician and Premier of New South Wales on five occasions. Robertson is best remembered for land reform and in particular the Robertson Land Acts of 1861, which sought to open up the selection of Crown land and break the monopoly of the squatters.

Robertson was elected to Parliament in 1856 supporting manhood suffrage, secret ballot, electorates based on equal populations, abolition of state aid to religion, government non-denominational schools, free trade, and land reform. He saw free selection of crown land before survey as the key to social reform with poor settlers being able to occupy agricultural and pastoral land, even that occupied by lease-holding squatters. This insight enabled him to dominate the politics of 1856–61.

Robertson was born at Bow, London, the fourth child and third son of James Robertson, a watchmaker and pastoralist from Scotland, and English woman Anna Marie Ripley, who married in Stepney, London in 1809. Subsequently, on the advice of Sir Thomas Brisbane, the then Governor of New South Wales, the family emigrated to Australia, arriving on the "Providence" on 8 January 1822. They were apparently in good circumstances, for, according to the custom of the time, anyone bringing to the colony a sum of not less than £2,500 was entitled to a first class grant of 2500 acres (10 km²) of land, and this they received in the Hunter Valley.

James Robertson senior worked as a watchmaker and silversmith, and became Supervisor of Governor Brisbane's astronomical instruments and clocks at the government observatory in the Parramatta Domain. He received a 35 hectare grant of land at Robertson's Point (subsequently Cremorne Point), on the north shore of Sydney Harbour.

At five years of age the young Robertson was sent to the new school in Sydney just opened by John Dunmore Lang. He subsequently attended schools kept by Bradley Gilchrist and W. T. Cape. Among his schoolfellows were two other boys also destined to become premiers of New South Wales, James Martin and William Forster.^{[citation needed]} On leaving school about the year 1833 Robertson went to sea and worked his passage to England where, through the medium of some letters of introduction, he accidentally came in contact with Lord Palmerston. The personality of the young man so impressed Palmerston that he invited him to stay with him for a few days in the country. There he introduced him to various distinguished people, and afterwards, when he was leaving England, gave him a letter to the New South Wales governor, Sir Richard Bourke.^{[citation needed]}

Robertson visited France and South America, and, after an absence of two years, left the sea and joined his family in northern New South Wales. He engaged in grazing and the farming of crops for some years. He married Margaret Emma "Madge" Davies when he was 22; they were to have three sons and six daughters. In 1842 he successfully submitted the protests of squatters to Governor Sir George Gipps, whose civil servants had attempted to restrict the expansion of grazing in northwestern New South Wales.

With the establishment of responsible government in 1856, Robertson stood for the Legislative Assembly seat of Phillip, Brisbane and Bligh, promising manhood suffrage, secret ballot, electorates based on equal populations, abolition of state aid to religion, government non-denominational schools, free trade, and free selection of crown lands before survey. Although unable to campaign due to poor health he easily defeated his conservative opponent, sitting with other liberals in the new parliament, and soon becoming their leader. He was convinced that agriculture was being unfairly handicapped by the land laws, and believed that social equilibrium could be achieved through land reform, gaining great support in both urban and rural areas as a result.

In January 1858, he joined the second Cowper ministry as Secretary for Lands and Public Works. He was largely responsible for amending the electoral law to introduce adult male franchise, increase Legislative Assembly seats from 54 to 80, although eight of these were abolished when Queensland separated in late 1859. It also included a seat for the University of Sydney once it had 100 graduates, which did not occur to 1876. In the June 1859 general election, he was re-elected to his seat, now called Upper Hunter. The Cowper government was defeated in October 1859, partly as a result of Robertson's opposition to the education bill. The succeeding Forster government was forced to resign when it lost a parliamentary vote in February 1860.