西部南极洲是指南极洲横贯南极山脉靠近太平洋的一侧地区，包括南极半岛，埃尔斯沃斯地，玛丽·伯德地以及威德尔海的龙尼-菲尔希纳冰架和罗斯海的罗斯冰架等地区。大部分位于西半球。

West Antarctica, or Lesser Antarctica, one of the two major regions of Antarctica, is the part of the continent that lies within the Western Hemisphere, and includes the Antarctic Peninsula. It is separated from East Antarctica by the Transantarctic Mountains and is covered by the West Antarctic Ice Sheet. It is separated from the main land mass of Antarctica by the Ross Sea, partly covered by the Ross Ice Shelf, and the Weddell Sea, largely covered by the Filchner-Ronne Ice Shelf. It may be considered a giant peninsula stretching from the South Pole towards the tip of South America.