Robert Island or Mitchells Island or Polotsk Island or Roberts Island is an island 11 miles (18 km) long and 8 miles (13 km) wide, situated between Nelson Island and Greenwich Island in the South Shetland Islands, Antarctica. Robert Island is located at 62°24′S 59°30′W / 62.400°S 59.500°W / -62.400; -59.500. Its surface area is 132 km (51 sq mi). The name "Robert Island" dates back to around 1821 and is now established in international usage.

Much of the Coppermine Peninsula in the west of the island is made up by a perched strandflat surface that was at sea level in the past.

Captain Richard Fildes may have named Robert Island for his brig Robert. Fildes was sealing in the South Shetlands in 1821–1822 until ice destroyed his vessel in March 1822. Fildes Strait is named for him.

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• Chart of South Shetland including Coronation Island, &c. from the exploration of the sloop Dove in the years 1821 and 1822 by George Powell Commander of the same. Scale ca. 1:200000. London: Laurie, 1822.
• South Shetland Islands. Scale 1:200000 topographic map. DOS 610 Sheet W 62 58. Tolworth, UK, 1968.
• L.L. Ivanov et al. Antarctica: Livingston Island and Greenwich Island, South Shetland Islands. Scale 1:100000 topographic map. Sofia: Antarctic Place-names Commission of Bulgaria, 2005.
• L.L. Ivanov. Antarctica: Livingston Island and Greenwich, Robert, Snow and Smith Islands. Scale 1:120000 topographic map. Troyan: Manfred Wörner Foundation, 2009. ISBN 978-954-92032-6-4
• Antarctic Digital Database (ADD). Scale 1:250000 topographic map of Antarctica. Scientific Committee on Antarctic Research (SCAR), 1993–2016.