| Settlement Type: | Former settlement |
| Pushpin Map: | California |
| Pushpin Label Position: | bottom |
| Pushpin Map Caption: | Location in California |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Name1: | California |
| Subdivision Type2: | County |
| Subdivision Name2: | Humboldt County |
| Coordinates: | 41.2081°N -123.7553°W |
| Elevation M: | 96 |
| Elevation Ft: | 315 |
Martins Ferry is a former settlement in Klamath County and later in Humboldt County, California. It lay on the Klamath River, at an elevation of . It still appeared on maps in 1983.
A post office operated at Martins Ferry from 1861 to 1862 and from 1865 to 1891. There was a military fort at the place in the 1860s. The name honors John F. Martin, its first postmaster, who also operated a ferry.