| Official Name: | O'Brien, Washington |
| Pushpin Map: | Washington#USA |
| Pushpin Label: | O'Brien |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Washington |
| Subdivision Type2: | County |
| Subdivision Name2: | King |
| Timezone: | Pacific (PST) |
| Utc Offset: | -8 |
| Timezone Dst: | PDT |
| Utc Offset Dst: | -7 |
| Coordinates: | 47.4122°N -122.2369°W |
| Postal Code Type: | ZIP code |
| Blank Name: | FIPS code |
| Blank1 Name: | GNIS feature ID |
O'Brien, Washington was a former community, north of Kent in the Green River Valley of King County in the U.S. state of Washington. It was just north of today's Green River Natural Resources Area, on the right bank of the river. At one time, it had a post office and a school.[1]
The community was named after Terrance O'Brien, the original owner of the town site.[2]