| Oracle | 35 | 2019 | Pak Haji Saka |
| Oras | 52 | 2021 | Sanlorenzo |
| Ordisi | 31.46 | 2002 | Astondoa S.A. (Astilleros) |
| Oreos | 40.8 | 2023 | Benetti SpA |
| Oriana | 29.3 | 1984 | Burger Boat Company |
| Oriel | 35.66 | 1992 | Y.B.M. Ltd |
| Orient Star | 47 | 2012 | CMB Yachts |
| Orient Star | 29.1 | 2008 | Sanlorenzo |
| Orinokia | 36.6 | 2007 | Benetti SpA |
| Orinoquia | 32.1 | 1992 | Broward Marine |
| Orion | 49.8 | 2025 | Heesen Yachts |
| Orion | 37.95 | 1984 | Feadship |
| Orion | 38.5 | 2009 | Sanlorenzo |
| Orion I | 28.27 | 2010 | Overmarine Group SPA |
| Orion Zephyr | 29.44 | 1993 | Trident |
| Orizzonte | 30 | 2020 | Vahali Shipyards |
| Orly Bliss | 42 | 2021 | Mengi Yay Yachts |
| Orpheus | 37.11 | 2025 | Numarine |
| Orso 3 | 31.75 | 2013 | Benetti SpA |
| Oryx | 40.2 | 2013 | Benetti SpA |
| Oryx of London | 31.7 | 1983 | Heesen Yachts |
| Oscar | 30.48 | 2003 | Azzura Yachts |
| Oscar | 37.11 | 2023 | Numarine |
| Oscar II | 31.52 | 1990 | Southern Ocean Yachts |
| Oslofjord | 28.63 | 2024 | Marlow Yachts |
| Osprey | 34.8 | 1953 | Hugh McLean & Sons |
| Ossum Dream | 29.16 | 2005 | Hargrave Custom Yachts |
| Ostar | 52 | 1998 | Feadship |
| Ostara | 43.29 | 2009 | Westport Yachts |
| Ottawa IV | 39 | 2016 | I-SEA Yachts |
| Oued Dahab | 30.7 | 1981 | Cantieri di Pisa |
| Our Aleph | 32.2 | 2022 | Sanlorenzo |
| Our Red Sea | 32.82 | 2024 | Custom Line |
| Our Way | 36.8 | 2004 | Tenix Defence |
| Our Way | 38.85 | 1998 | Palmer Johnson Yachts |
| Ouranos | 49.6 | 2016 | Admiral |
| Ours | 31.8 | 2023 | Overmarine Group SPA |
| Out of the Blue | 35.2 | 2020 | Sunseeker |
| Outta Touch | 32 | 2001 | Intermarine Savannah |
| Ouzo Palace | 30.48 | 2004 | Azimut Yachts |
| Ovation | 30.48 | 2021 | Jim Smith Tournament Boats Inc. |
| Over the rainbow of London | 35 | 1930 | Dickie & Sons |
| Oxygen | 42 | 2009 | Baglietto S.p.A. |
| Oya | 30.54 | 1989 | Camper & Nicholsons Shipyard |
| Oz Sea | 30.78 | 2009 | Hargrave Custom Yachts |
| Ozone | 28.74 | 2011 | Peri Yachts |
| P | 28 | 2001 | Canados |
| PAB | 31.9 | 2003 | Admiral |
| Pacha III | 36.25 | 1936 | Camper & Nicholsons Shipyard |
| Pachamama | 43.65 | 2015 | Baglietto S.p.A. |
