The Eucumbene River rises below Shaw Hill, in the northern part of the Kosciuszko National Park, approximately 10 kilometres (6.2 mi) north of the village of Kiandra. The river flows generally south and southeast before emptying into Lake Eucumbene where its flow is impounded by Eucumbene Dam. After passing through or over the dam wall, the river flows generally south before emptying into Lake Jindabyne, impounded by Jindabyne Dam. Within Lake Jindabyne, the river reaches its confluence with the Snowy River.
The river descends 476 metres (1,562 ft) over its 84 kilometres (52 mi) course, joined by seven minor tributaries.
The flow of the river is impacted by alpine conditions; with high flows during spring as a result of snow melt. Meanwhile, during winter, the river is subject to snow and ice conditions.