| Game |
| Result | Moves |
Year |
Event/Locale | Opening |
| 1. Blackburne vs J O'Hanlon |
 | 1-0 | 22 |
1896 |
BMX Belfast | C25 Vienna |
| 2. J O'Hanlon vs R G Dixon Addey |
| 1-0 | 27 |
1915 |
IRL-ch | D07 Queen's Gambit Declined, Chigorin Defense |
| 3. J O'Hanlon vs H Price |
| 0-1 | 22 |
1919 |
Edinburgh op | C29 Vienna Gambit |
| 4. Euwe vs J O'Hanlon |
 | 1-0 | 29 |
1919 |
Hastings | C54 Giuoco Piano |
| 5. J O'Hanlon vs W H Kirk |
| 1-0 | 38 |
1919 |
Hastings-C | D61 Queen's Gambit Declined, Orthodox, Rubinstein Attack |
| 6. J O'Hanlon vs Euwe |
| 1-0 | 19 |
1921 |
? | D08 Queen's Gambit Declined, Albin Counter Gambit |
| 7. G Norman vs J O'Hanlon |
| 1-0 | 43 |
1921 |
Hastings 2122 | C13 French |
| 8. Yates vs J O'Hanlon |
 | 1-0 | 3 |
1921 |
Hastings 2122 | C60 Ruy Lopez |
| 9. J O'Hanlon vs B Kostic |
| 0-1 | 23 |
1921 |
Hastings 2122 | B29 Sicilian, Nimzovich-Rubinstein |
| 10. J O'Hanlon vs E Voellmy |
| 0-1 | 24 |
1924 |
Paris ol (Men) f-B | C45 Scotch Game |
| 11. M Romi vs J O'Hanlon |
| 0-1 | 29 |
1924 |
Paris, finale | C13 French |
| 12. J O'Hanlon vs Koltanowski |
| 0-1 | 27 |
1924 |
ol final B | D46 Queen's Gambit Declined Semi-Slav |
| 13. J O'Hanlon vs R Grau |
| 0-1 | 26 |
1924 |
Paris ol (Men) prel-3 | C14 French, Classical |
| 14. J O'Hanlon vs Euwe |
| 0-1 | 44 |
1924 |
Paris prel-3 ;HCL 33 | B83 Sicilian |
| 15. F Hobson vs J O'Hanlon |
| 0-1 | 19 |
1928 |
? | C78 Ruy Lopez |
| 16. J O'Hanlon vs A McDonagh |
| 1-0 | 24 |
1928 |
? | C73 Ruy Lopez, Modern Steinitz Defense |
| 17. Colle vs J O'Hanlon |
 | 1-0 | 20 |
1930 |
Nice | D05 Queen's Pawn Game |
| 18. Tartakower vs J O'Hanlon |
 | 1-0 | 48 |
1930 |
Nice | D30 Queen's Gambit Declined |
| 19. R Krogius vs J O'Hanlon |
| 1-0 | 24 |
1935 |
Olympiad | C07 French, Tarrasch |
| 20. Marshall vs J O'Hanlon |
| 1-0 | 19 |
1935 |
Warsaw | D52 Queen's Gambit Declined |
| 21. J O'Hanlon vs A Staehelin |
| 0-1 | 42 |
1935 |
Olympiad | C01 French, Exchange |
| 22. Feigin vs J O'Hanlon |
| 1-0 | 45 |
1935 |
Olympiad | D51 Queen's Gambit Declined |
| 23. S Rosselli del Turco vs J O'Hanlon |
| 1-0 | 36 |
1935 |
Olympiad | D04 Queen's Pawn Game |
| 24. I Pleci vs J O'Hanlon |
| 1-0 | 28 |
1935 |
Warsaw ol (Men) | D37 Queen's Gambit Declined |
| 25. J O'Hanlon vs A Muffang |
| 0-1 | 42 |
1935 |
Olympiad | B03 Alekhine's Defense |