O'Brien is an unincorporated community and census-designated place (CDP) in Josephine County, Oregon, United States.

The unemployment rate is 6.9%, slightly higher than the national average of 5.2% [3] The community was named after John O'Brien, who was one of the first settlers to arrive at the locality.

These include Mann's O'Brien Country Store and Discount Gas, a post office with the zip code 97534, a fire station, the McGrew's restaurant, and the Lone Mountain RV Park.

[3] O'Brien has a climate that is a Mediterranean (CSA) in nature with hot and dry summer days and cool and wet winters.

It is also subtropical in nature due to its hot summer days, some of the hottest in Oregon, with temps often topping 95 °F (35 °C).