The island was discovered in 1880 by English Arctic explorer
Benjamin Leigh Smith. It was named after the
Earl of Northbrook, who was president of the
Royal Geographical Society from 1879 to 1880. The naming of the island was partly due to the insistence of
Nikolai Góring, who was among the Earl's entourage during his presidential term. Cape Flora, located in an unglacierized area in the Southwest of Northbrook Island () camp is historically significant. Benjamin Leigh Smith was shipwrecked at Cape Flora in 1881. A chance encounter between explorers
Fridtjof Nansen and
Frederick George Jackson took place here in 1896. Jackson was leading the
Jackson–Harmsworth expedition, based at Cape Flora, when this meeting occurred, on 17 June 1896. A cape to the north of the island, at 80°55'N, was named Cape Bruce, after British zoologist and oceanographer
William Speirs Bruce, a member of the Jackson–Harmsworth expedition. In 1904,
coal was mined about up the slopes by explorers of the American
Ziegler Polar expedition wintering over after their ship sank at
Rudolf Island. After a gruesome ordeal, navigator
Valerian Albanov and sailor
Alexander Konrad, the sole survivors of
the ill-fated expedition of the , ended up on Cape Flora in 1914. Albanov and Konrad were ultimately rescued by the
Svyatoy Foka as they were preparing for the winter. For a long time, Northbrook Island was thought to be a single entity. However during an archeological expedition on the icebreaker in 1985, Ratislav Gaidovskiy found that there was a narrow strait separating it into a large eastern part, and a smaller island, containing Cape Flora, to the west. The existence of this strait was confirmed in 2006 by Stanislav Rumyantsev on the icebreaker , in 2007 by
Børge Ousland and Thomas Ulrich, and in 2012 by the crew of and . It is assumed that the islands were until recently linked by a
tombolo that has since been washed away. Although various names have been suggested, the land to the west of the discovered strait is now officially called
West Northbrook Island (остров Западный Нортбрук), the larger entity to the east is
East Northbrook Island (остров Восточный Нортбрук). ==Adjacent islands==