| Obunsha Deru-jun - Chiri DS (Japan) | |
| Obunsha Deru-jun - Chiri DS (Japan) (Rev 1) | |
| Obunsha Deru-jun - Kokugo DS (Japan) | |
| Obunsha Deru-jun - Koumin DS (Japan) | |
| Obunsha Deru-jun - Rekishi DS (Japan) | |
| Obunsha Deru-jun - Rika DS (Japan) | |
| Obunsha Deru-jun - Sansuu DS (Japan) | |
| Ochaken no Daibouken - Honwaka Yumemiru Sekai Ryokou (Japan) | |
| Ochaken no Daibouken 2 - Yume Ippai no Omocha Bako (Japan) | |
| Ochaken no Heya DS (Japan) | |
| Ochaken no Heya DS 2 (Japan) | |
| Ochaken no Heya DS 2 (Japan) (Rev 1) | |
| Ochaken no Heya DS 3 (Japan) | |
| Ochaken no Heya DS 3 (Japan) (Rev 1) | |
| Ochaken no Heya DS 4 (Japan) | |
| Oden-kun - Tanoshii Oden Mura (Japan) | |
| Odoru Daisousa-sen - The Game - Sensuikan ni Sennyuu Seyo! (Japan) | |
| Oekaki Puzzle Battle! - Yuusha Ou GaoGaiGar Hen (Japan) | |
| Ogwangui Darin DS (Korea) | |
| Oheya o Kazarou - Koinu no Heya (Japan) | |
| Ohimesama Debut (Japan) | |
| Oide yo Doubutsu no Mori (Japan) | |
| Oide yo Doubutsu no Mori (Japan) (Rev 1) | |
| Oishiku Kiwameru Shokutsuu DS - Otona no Shuumatsu Henshuubu Gensen no Osusume Omise Jouhou Iri (Japan) | |
| Oishinbo - DS Recipe Shuu (Japan) | |
| Ojaru-Maru DS - Ojaru to Okeiko Aiueo (Japan) | |
| OK! - First for Celebrity News - Puzzle Stars (Europe) | |
| Okada Toshio no Itsumademo Debu to Omounayo - DS de Recording Diet (Japan) | |
| Okaeri! Chibi-Robo! - Happy Rich Oosouji! (Japan) | |
| Oktoberfest - The Official Game (Europe) (En,Fr,De,Es,It) | |
| OMG 26 - Our Mini Games (USA) | |
| One Piece - Gear Spirit (Japan) | |
| One Piece - Gear Spirit (Korea) | |
| One Piece - Gigant Battle! (Europe) | |
| One Piece - Gigant Battle! (France) | |
| One Piece - Gigant Battle! (Germany) | |
| One Piece - Gigant Battle! (Japan) | |
| One Piece Gigant Battle 2 - Shin Sekai (Japan) | |
| Onegai My Melody - Yume no Kuni no Daibouken (Japan) | |
| Oni Zero - Sengoku Ranse Hyakka Ryouran (Japan) | |
| Onsei Kanjou Sokuteiki - Kokoro Scan (Japan) | |
| Ontama - Onpu-tou Hen (Japan) | |
| Ontamarama (USA) | |
| Ookami Den - Chiisaki Taiyou (Japan) | |
| Ookami Den (Europe) | |
| Ookami Den (USA) | |
| Ookami to Koushinryou - Boku to Holo no Ichinen (Japan) | |
| Ookami to Koushinryou - Umi o Wataru Kaze (Japan) | |
| Ookiku Furikabutte - Honto no Ace ni Nareru kamo (Japan) | |
| Open Season (Europe) (En,Es,It,Nl) | |