| Regimental number | 982 |
| Date of birth | |
| Place of birth | Drangan, Co. Tipperary, Ireland |
| School | Drangan High School, Co. Tipperary, Ireland |
| Age on arrival in Australia | 24 |
| Religion | Roman Catholic |
| Occupation | Warder |
| Address | Hospital for Insane, Claremont, Western Australia |
| Marital status | Single |
| Age at embarkation | 25 |
| Next of kin | Father, Hugh O'Brien, Carrick on Suir, Tipperary, Ireland |
| Enlistment date | |
| Rank on enlistment | Private |
| Unit name | 44th Battalion, Headquarters |
| AWM Embarkation Roll number | 23/61/1 |
| Embarkation details | Unit embarked from Fremantle, Western Australia, on board HMAT A29 Suevic on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 44th Battalion |
| Fate | Returned to Australia |
| Family/military connections | Brothers: 106 Lance Corporal Rufus Hugh O'BRIEN, 44th Bn, returned to Australia, 25 January 1919; 1639 Bombardier John O'BRIEN, 11th Field Artillery Brigade, returned to Australia, 9 December 1918. |
| Other details |
War service: Western Front Medals: British War Medal, Victory Medal |
| Date of death | |
| Age at death | 66 |
| Place of burial | Karrakatta Cemetery, Perth, Western Australia |