| Regimental number | R177 |
| Religion | Roman Catholic |
| Occupation | Bootmaker |
| Address | 18 Turner Street, Redfern, Sydney, New South Wales |
| Marital status | Single |
| Age at embarkation | 25 |
| Next of kin | Father, P O'Brien, 18 Turner Street, Redfern, Sydney, New South Wales |
| Enlistment date | 25 August 1914 |
| Date of enlistment from Nominal Roll | 24 August 1914 |
| Rank on enlistment | Private |
| Unit name | 1st Field Ambulance, Reinforcement 14 |
| AWM Embarkation Roll number | 26/44/3 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board RMS Osterley on 15 January 1916 |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 7th Field Ambulance |
| Fate | Returned to Australia 4 June 1919 |
| Miscellaneous details (Nominal Roll) | *Spelt John Steven O'Brien on NR. Appears to have enlisted twice. John Stevens O'Brien, Regimental No. 177 |
