| Octomania | Wii | 2007 | Compile Heart |
| Odama | Nintendo GameCube | 2006 | Vivarium Inc. |
| Oddworld: Abe's Oddysee | Game Boy | 1997 | Oddworld Inhabitants |
| Of Mice and Sand | Nintendo 3DS | 2016 | Arc System Works |
| Off Road | Wii | 2008 | Razorworks |
| Ogre Battle: The March of the Black Queen | Super Nintendo Entertainment System | 1993 | Quest |
| Ohenro-San | Nintendo GameCube | 2003 | Panasonic Holdings Corporation |
| Ohno Odyssey | Nintendo 3DS | 2013 | Arc System Works, Big John Games |
| Oishii Puzzle wa Irimasen ka? | Super Nintendo Entertainment System | 1996 | — |
| Oishinbo: Kyūkyoku no Menu 3-bon Shōbu | Nintendo Entertainment System | 1989 | Tose Co. |
| Okamoto Ayako to Match Play Golf | Super Nintendo Entertainment System | 1994 | — |
| Okkotoshi Puzzle Tonjan!? | Nintendo Entertainment System | 1989 | NMK |
| Old Testament Megami-Tensei | Super Nintendo Entertainment System | 1995 | — |
| Olympic Summer Games | Super Nintendo Entertainment System, Game Boy | 1996 | Silicon Dreams Studios, Tiertex Design Studios |
| One Piece: Grand Adventure | Nintendo GameCube | 2006 | Ganbarion |
| One Piece: Grand Battle 3 | Nintendo GameCube | 2003 | Ganbarion |
| One Piece: Grand Battle! | Nintendo GameCube | 2005 | Ganbarion |
| One Piece: Pirates' Carnival | Nintendo GameCube | 2005 | h.a.n.d. |
| One Piece: Super Grand Battle! X | Nintendo 3DS | 2014 | — |
| One Piece: Treasure Battle! | Nintendo GameCube | 2002 | — |
| One Piece: Unlimited Adventure | Wii | 2007 | Ganbarion |
| One Piece: Unlimited Cruise | Wii | 2008 | Ganbarion |
| One Piece: Unlimited Cruise 1 – The Treasure Beneath the Waves | Wii | 2008 | Hudson Soft |
| One Piece: Unlimited Cruise 2 – Awakening of a Hero | Wii | 2009 | Ganbarion |
| One Piece: Unlimited Cruise SP | Nintendo 3DS | 2011 | Ganbarion |
| One Piece: Unlimited World Red | Nintendo 3DS | 2013 | Ganbarion |
| OneChanbara: Bikini Zombie Slayers | Wii | 2008 | Tamsoft |
| Ongaku Tsukūru: Kanadeeru | Super Nintendo Entertainment System | 1996 | Success |
| Onita Atsushi FMW | Super Nintendo Entertainment System | 1993 | — |
| Onizuka Katsuya Super Virtual Boxing | Super Nintendo Entertainment System | 1993 | Sting |
| Onslaught | Wii | 2009 | Quintet |
| Onyanko Town | Nintendo Entertainment System | 1985 | Micronics |
| Open Season | Nintendo GameCube, Wii | 2006 | Ubisoft Montreal |
| Operation C | Game Boy | 1991 | Konami |
| Operation Europe: Path to Victory | Super Nintendo Entertainment System | 1993 | Koei |
| Operation Logic Bomb | Super Nintendo Entertainment System | 1993 | Jaleco |
| Operation Secret Storm | Nintendo Entertainment System | 1992 | — |
| Operation Thunderbolt | Super Nintendo Entertainment System | 1988 | Taito |
| Operation Wolf | Nintendo Entertainment System | 1987 | Taito |
| Opoona | Wii | 2007 | ArtePiazza |
| Orb-3D | Nintendo Entertainment System | 1990 | Mindscape |
| Orbient | Wii | 2006 | skip Ltd. |
| Order Up! | Nintendo 3DS, Wii | 2008 | SuperVillain Studios |
| Original Japanese Release of Chrono Trigger | Super Nintendo Entertainment System | 1995 | — |
| Oscar | Super Nintendo Entertainment System | 1993 | Flair Software |
| Osomatsu-kun: Back to the me no Deppa no Maki | Nintendo Entertainment System | 1989 | Shinsei |
| Osouji Sentai Clean Keeper | Wii | 2008 | Lupinus, Idea Factory |
| Osu!! Karate Bu | Super Nintendo Entertainment System | 1994 | — |
| Otaku no Seiza: An Adventure in the Otaku Galaxy | Nintendo Entertainment System | 1991 | Advance Communication |
| Othello | PlayStation Vita, Nintendo 3DS, Wii | 2009 | Arc System Works |
| Othello | Nintendo Entertainment System | 1986 | HAL Laboratory |
| Otoboke Ninja Colosseum | Super Nintendo Entertainment System | 1995 | — |
| Otogirisō | Super Nintendo Entertainment System | 1992 | Chunsoft |
| Out of Gas | Game Boy | 1992 | Realtime Associates |
| Out to Lunch | Super Nintendo Entertainment System | 1993 | Mindscape |
| Outdoor Action Double Pack | Wii | 2010 | Mastiff |
| Outlander | Super Nintendo Entertainment System | 1993 | Mindscape |
| Outlanders | Nintendo Entertainment System | 1987 | Micronics, Micronics |
| Outlaw Golf | Nintendo GameCube | 2002 | Simon & Schuster, Hypnotix |
| OutRun 2 | Nintendo GameCube | 2003 | Sega AM2 |