Banks made his name on the 1766 natural history expedition to Newfoundland and Labrador. He took part in Captain James Cook's first great voyage (1768–1771), visiting Brazil, Tahiti, and, after 6 months in New Zealand, Australia, returning to immediate fame. He held the position of President of the Royal Society for over 41 years. He advised King George III on the Royal Botanic Gardens, Kew, and by sending botanists around the world to collect plants, he made Kew the world's leading botanical gardens.
Banks advocated British settlement in New South Wales and colonisation of Australia, as well as the establishment of Botany Bay as a place for the reception of convicts, and advised the British government on all Australian matters. He is credited with introducing the eucalyptus, acacia, and the genus named after him, Banksia, to the Western world. Approximately 80 species of plants bear his name. He was the leading founder of the African Association and a member of the Society of Dilettanti which helped to establish the Royal Academy.
Banks was born on Argyle Street in London to William Banks, a wealthy Lincolnshire country squire and member of the House of Commons, and his wife Sarah, daughter of William Bate. He had a younger sister, Sarah Sophia Banks, born in 1744.
As a boy, Banks enjoyed exploring the Lincolnshire countryside and developed a keen interest in nature, history and botany. When he was 17, he was inoculated with smallpox, but he became ill and did not return to school. In late 1760, he was enrolled as a gentleman-commoner at the University of Oxford. At Oxford, he matriculated at Christ Church, where his studies were largely focused on natural history rather than the classical curriculum. Determined to receive botanical instruction, he paid the Cambridge botanist Israel Lyons to deliver a series of lectures at Oxford in 1764.
Banks left Oxford for Chelsea in December 1763. He continued to attend the university until 1764, but left that year without taking a degree. His father had died in 1761, so when he turned 21 he inherited the impressive estate of Revesby Abbey, in Lincolnshire, becoming the local squire and magistrate, and sharing his time between Lincolnshire and London. From his mother's home in Chelsea he kept up his interest in science by attending the Chelsea Physic Garden of the Worshipful Society of Apothecaries and the British Museum, where he met Daniel Solander. He began to make friends among the scientific men of his day and to correspond with Carl Linnaeus, whom he came to know through Solander. As Banks's influence increased, he became an adviser to King George III and urged the monarch to support voyages of discovery to new lands, hoping to indulge his own interest in botany. He became a Freemason sometime before 1769.