| Bylong River | |
| Name Other: | Bylong Creek[1] |
| Subdivision Type1: | Country |
| Subdivision Name1: | Australia |
| Subdivision Type2: | State |
| Subdivision Name2: | New South Wales |
| Subdivision Type3: | Region |
| Subdivision Name3: | NSW North Coast (IBRA), Central Tablelands, Hunter |
| Subdivision Type5: | Local government area |
| Subdivision Name5: | Mid-Western Regional |
| Length Km: | 48 |
| Source1: | Wollemi National Park, Great Dividing Range |
| Source1 Location: | near Rylstone |
| Source1 Elevation: | 748m (2,454feet) |
| Mouth: | confluence with the Goulburn River |
| Mouth Location: | north of Bylong |
| Mouth Elevation: | 218m (715feet) |
| River System: | Hunter River catchment |
| Tributaries Left: | Cousins Creek, Growee River, Coggan Creek |
| Tributaries Right: | Reedy Creek (New South Wales), Wattle Creek, Lee Creek (New South Wales), Dry Creek (Bylong River) |
| Custom Label: | National park |
| Custom Data: | Wollemi NP |
| Extra: | [2] |
Bylong River, a perennial river of the Hunter River catchment, is located in the Central Tablelands and Upper Hunter regions of New South Wales, Australia.
Bylong River rises in the central tablelands of the Capertee Valley, within Wollemi National Park, on the north-western slopes of the Great Dividing Range, below Goat Mountain, and flows generally north-east, joined by seven tributaries, including the Growee River, before reaching its confluence with the Goulburn River, north of the village of Bylong. The river descends over its course.[2]
The Goulburn River eventually flows into the Hunter River, a major waterway which flows into the Tasman Sea at Newcastle.