| Marchington River | |
| Pushpin Map: | Canada Ontario |
| Pushpin Map Caption: | Location of the mouth of the Marchington River in Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type3: | Region |
| Subdivision Name3: | Northwestern Ontario |
| Subdivision Type4: | Districts |
| Length: | 118km (73miles) |
| Source1: | Kashaweogama Lake |
| Source1 Location: | Thunder Bay District |
| Source1 Coordinates: | 50.3994°N -90.8697°W |
| Source1 Elevation: | 390m (1,280feet) |
| Mouth: | Abram Lake |
| Mouth Location: | Kenora District |
| Mouth Coordinates: | 50.0964°N -91.8039°W |
| Mouth Elevation: | 357m (1,171feet) |
| River System: | Hudson Bay drainage basin |
| Tributaries Left: | Houghton Creek, Drive Creek, Sturgeon River, Martin Creek |
| Tributaries Right: | North River, Runway Creek |
The Marchington River is a river in the Hudson Bay drainage basin located in Kenora and Thunder Bay Districts in northwestern Ontario, Canada. It travels 78km (48miles) from its head at Kashaweogama Lake in Thunder Bay District through a series of lakes to Marchington Lake, where it meets the Sturgeon River and North River. It then continues 30km (20miles) over the small McDougall Falls and through Botsford Lake before emptying into the English River at Abram Lake near Sioux Lookout.
Highway 516 crosses the river approximately 6.51NaN1 north of its confluence with Marchington Lake. Highway 642 and the CN transcontinental rail line cross the river about 41NaN1 and 21NaN1 respectively upstream of the mouth, near Superior Junction.