Jack O'Brien boxer
- bouts
- 4
- won
- 1
- lost
- 2
- draw
- 1
- Status
- inactive
- Division
- lightweight
- Debut
- 1919-12-23
- Height
- -
- Reach
- -
- Age
- -
- Born
- -
- Death
- -
- Nationality
- USA
| Date | Opponent | Last Opponents' Results | Place | Result |
|---|---|---|---|---|
| 1921-04-05 | Battling Abrew | debut | Stockton | LOST KO |
| 1920-10-26 | Felix Villamore | LLWLLD | Garibaldi Hall, San Francisco | LOST KO |
| 1920-05-13 | Fred Edwards | debut | Airdrome, Vallejo | WIN Technical knockout |
| 1919-12-23 | Dago Jimmy Lewis | WDWDWL | Vallejo | DRAW Points |