Antarctica has no indigenous population and there is no evidence that it was seen by humans until the 19th century. However, belief in the existence of a Terra Australis – a vast continent in the far south of the globe to "balance" the northern lands of Europe, Asia and North Africa – had existed since the times of Ptolemy (1st century AD), who suggested the idea to preserve the symmetry of all known landmasses in the world. Even in the late 17th century, after explorers had found that South America and Australia were not part of the fabled "Antarctica", geographers believed that the continent was much larger than its actual size.

Painting of James Weddell's second expedition in 1823, depicting the brig Jane and the cutter Beaufroy.A key part of the story of how Antarctica got its name is how it did not get named Terra Australis. Australia got named after this instead, and it was because of the mistake made by people who had decided that no significant land mass further south of Australia would be found. Explorer Matthew Flinders, in particular, has been credited with popularizing the transfer of the name Terra Australis to Australia. He justified the titling of his book A Voyage to Terra Australis (1814) by writing in the introduction:

There is no probability, that any other detached body of land, of nearly equal extent, will ever be found in a more southern latitude; the name Terra Australis will, therefore, remain descriptive of the geographical importance of this country, and of its situation on the globe: it has antiquity to recommend it; and, having no reference to either of the two claiming nations, appears to be less objectionable than any other which could have been selected.

European maps continued to show this hypothesized land until Captain James Cook's ships, HMS Resolution and Adventure, crossed the Antarctic Circle on 17 January 1773, in December 1773 and again in January 1774. Cook came within about 121 km of the Antarctic coast before retreating in the face of field ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals. According to various organizations (the National Science Foundation, NASA, the University of California, San Diego, and other sources), ships captained by three men sighted Antarctica in 1820: Fabian Gottlieb von Bellingshausen (a Baltic German captain in the Imperial Russian Navy), Edward Bransfield (an Irish-born captain in the Royal Navy), and Nathaniel Palmer (an American sealer out of Stonington, Connecticut). Von Bellingshausen saw Antarctica on 27 January 1820, three days before Bransfield sighted land, and ten months before Palmer did so in November 1820. On that day the expedition led by Von Bellingshausen and Mikhail Lazarev on ships Vostok and Mirny reached a point within 32 km of the Antarctic mainland and saw ice fields there. The first documented landing on mainland Antarctica was by the American sealer John Davis in West Antarctica on 7 February 1821, although some historians dispute this claim.

In December 1839, as part of the United States Exploring Expedition of 1838–42 conducted by the United States Navy (sometimes called the "Ex. Ex.", or "the Wilkes Expedition"), an expedition sailed from Sydney, Australia, into the Antarctic Ocean, as it was then known, and reported the discovery "of an Antarctic continent west of the Balleny Islands" on 25 January 1840. That part of Antarctica was later named "Wilkes Land", a name it maintains to this day.

Explorer James Clark Ross passed through what is now known as the Ross Sea and discovered Ross Island (both of which were named for him) in 1841. He sailed along a huge wall of ice that was later named the Ross Ice Shelf. Mount Erebus and Mount Terror are named after two ships from his expedition: HMS Erebus and Terror. Mercator Cooper landed in East Antarctica on 26 January 1853.

Roald Amundsen and his crew looking at the Norwegian flag at the South Pole, 1911During the Nimrod Expedition led by Ernest Shackleton in 1907, parties led by Edgeworth David became the first to climb Mount Erebus and to reach the South Magnetic Pole. Douglas Mawson, who assumed the leadership of the Magnetic Pole party on their perilous return, went on to lead several expeditions until retiring in 1931. In addition, Shackleton himself and three other members of his expedition made several firsts in December 1908 – February 1909: they were the first humans to traverse the Ross Ice Shelf, the first to traverse the Transantarctic Mountain Range (via the Beardmore Glacier), and the first to set foot on the South Polar Plateau. An expedition led by Norwegian polar explorer Roald Amundsen from the ship Fram became the first to reach the geographic South Pole on 14 December 1911, using a route from the Bay of Whales and up the Axel Heiberg Glacier. One month later, the doomed Scott Expedition reached the pole.

Richard E. Byrd led several voyages to the Antarctic by plane in the 1930s and 1940s. He is credited with implementing mechanized land transport on the continent and conducting extensive geological and biological research. However, it was not until 31 October 1956 that anyone set foot on the South Pole again; on that day a U.S. Navy group led by Rear Admiral George J. Dufek successfully landed an aircraft there.

The first person to sail single-handed to Antarctica was the New Zealander David Henry Lewis, in 1972, in a 10-meter steel sloop Ice Bird.