PlayStation 2 - O
- Oanechan Bara
- Oanechan Blue
- Oanechanbara Blue
- Obscure
- Obscure - the Aftermath
- Obscure 2
- Oddworld - Abe's Exoddus
- Odin Sphere
- Off-Road Wide Open
- Okage - Shadow King
- Okami
- Olympic Summer Games
- Omega Boost
- One Piece - Grand Adventure
- One Piece - Grand Battle
- One Piece - Grand Battle! 3
- One Piece - Grand Battle! Rush
- One Piece - Pirate's Carnival
- One Piece - Pirates Carnival
- One Piece Grand Battle 2
- One Piece Grand Battle 3
- One Piece Grand Battle! 3
- One Piece Mansion
- Oneechanbara
- Oneechanbara 2
- Oni
- Onimusha
- Onimusha - Blade Warriors
- Onimusha - Buraiden
- Onimusha - Dawn of Dreams
- Onimusha - Warlords
- Onimusha 2
- Onimusha 2 - Samurai`s Destiny
- Onimusha 2 - Samurai's Destiny
- Onimusha 3
- Onimusha 3 - Demon Siege
- Onimusha 4 - Dawn of Dreams
- Onimusha Blade Warriors
- Onimusha Buraiden
- Onumusha 3
- Open Season
- Operation WinBack
- Operation Winback 2 - Project Poseidon
- Operator's Side
- Operator's Side - FAQ
- Option Tuning Car Battle 2
- Orochi Warriors
- Orphen
- Orphen - the Scion of Sorcery
- Orphen - Scion of Sorcery
- Otostaz
- Ougon Kishi Garo
- Outlaw Golf 2
- Outlaw Tennis
- Outlaw Volleyball Remixed
- OutRun 2006
- OutRun 2006 - Coast 2 Coast
- OutRun 2006 - Coast to Coast
- OutRun2 SP Special Tours
- Over the Hedge
- Over the Monochrome Rainbow
- Overblood
- Overblood 2
- Oz