The flag of South Georgia and the South Sandwich Islands was granted on 3 October 1985, when the Territory was created. Previously the Territory was a part of the Falkland Islands Dependency and used the same flag.
The new territory of South Georgia and the South Sandwich Islands (SGSSI) was created in 1985, as is evidenced by the letters patent and order in council that are shown in full on the South Georgia government website. Prior to 1985, the area had been administered as a dependency of the Falkland Islands. The arms of South Georgia and the South Sandwich Islands were granted by royal warrant on February 14, 1992. The website of the SGSSI has a copy of the warrant, which addresses the arms only, and does not mention any flag. After the arms were granted in February 1992, the government of SGSSI started using them on the British Blue Ensign as is customary in British dependencies. The Flag Bulletin, XXXII:2 (1993), describes the badge which was granted on 14 February 1992 to celebrate the liberation of the islands from Argentine occupation. It consists of a shield (lozengy argent and azure, on a pile vert a lion rampant or, armed and langued gules, holding a torch or, inflamed gules, and in chief two estoiles or), a reindeer crest, as supporters a fur seal and a macaroni penguin, and the motto Leo Terram Propriam Protegat ('Let the lion protect its own land').
The original flag had a smaller version of the coat-of-arms displayed in a white disc, but this was later changed to the current flag. In June 2006, the College of Arms in Newsletter No. 9 said, "South Georgia and Sandwich Islands: the flag of this overseas territory, illustrated left, has been approved by Her Majesty and accordingly placed on record at the College of Arms, along with the flag of the commissioner of the territory. College reference: Standards 5/96, 97." The flag that is illustrated in Newsletter No. 9 shows the arms in full, without a white disc.
The flag is a blue ensign, with the Union Flag in the canton, defaced with the coat-of-arms. The flag flies over the main government settlements on South Georgia Island, and the scientific bases of the British Antarctic Survey.