Jack O'Brien boxer
- bouts
- 12
- won
- 6
- lost
- 2
- draw
- 4
- Status
- inactive
- Division
- -
- Debut
- 1896-10-20
- Height
- -
- Reach
- -
- Age
- -
- Born
- -
- Death
- -
- Nationality
- USA
| Date | Opponent | Last Opponents' Results | Place | Result |
|---|---|---|---|---|
| 1903-08-07 | Young Cahill | WDWLW | Lenox A.C., Boston | WIN Points |
| 1903-04-29 | Young Manning | L | Tammany A.C., Boston | WIN Technical knockout |
| 1903-04-13 | Jack Flavin | DWLDD | Sarsfield A.C., Boston | DRAW Points |
| 1902-02-18 | Dan Snyder | LDLWDL | Columbian A.C., East Boston | DRAW Points |
| 1900-04-19 | Billy Gardner | WWWDDL | Crescent A.C., Brockton | LOST Technical knockout |
| 1900-01-25 | Young Mack | debut | Crescent A.C., Brockton | WIN Technical knockout |
| 1899-09-12 | Jimmy Gorman | WWWWLW | Troy | WIN Points |
| 1899-08-12 | Jim Popp | WLDWDW | Hawthorne Club, Cheektowaga | WIN Technical knockout |
| 1898-11-15 | Jack Hamilton | DWDLWD | Manhattan A.C., Troy | WIN Points |
| 1898-10-18 | Jack Hamilton | WDWDLW | Manhattan A.C., Troy | DRAW Points |
| 1898-05-02 | Jig Stone | debut | City Point A.C., Boston | LOST Technical knockout |
| 1896-10-20 | Eddie Ford | DL | Wharton Hall, Philadelphia | DRAW Points |