King Oscar Fjord, Glacial fjord in Northeast Greenland National Park, Greenland

King Oscar Fjord is a fjord in Northeast Greenland, 145 km long and 10–25 km wide, marking the northern border of the Scoresby Land peninsula. Traill Island and Geographical Society Island bound it to the east, Ella Island lies at its inner northern end, and Davy Sound connects it to the Greenland Sea. The Antarctic Sound links it north to the Kaiser Franz Joseph Fjord system.

Swedish explorer A.G. Nathorst named this fjord in 1899 in honor of King Oscar II of Sweden, who reigned from 1872 to 1907. The naming came during a scientific expedition that mapped the northeastern coast of Greenland.

The fjord's name honours Oscar II, king of Sweden from 1872 to 1907 and of Norway until 1905, given by A.G. Nathorst on his 1899 expedition. Along the shores, place names from that Swedish survey remain in use, including Segelsällskapet Fjord, Röhss Fjord and Rhedin Fjord.

Summer months offer the best conditions for visiting, when sea ice recedes enough for expedition vessels to navigate the fjord. Expect strong winds and rapidly changing weather, so heavy insulated and waterproof clothing is necessary for any visit.

The fjord's name honours Oscar II, who was King of Sweden from 1872 to 1907 and also King of Norway until 1905, when the union was dissolved. A.G. Nathorst gave the name in 1899 as Konung Oscars Fjord, so the waterway carries the title of a monarch who reigned over two separate kingdoms.