- off white
- OFFBOWERY
- OKCSC
- OKIRAKU
- OKUTA
- Oladance
- Olasonic
- Oliso
- OLIVE des OLIVE
- OM SYSTEM
- Omars
- OMASI
- OmegaLine
- OmiCam
- Omnicharge
- ON-LIFE
- onanoff
- ondo
- ONE
- one after another NICE CLAUP
- ONE-NETBOOK Technology
- ONE-NETBOOK Technology OneMix
- one'sterrace
- OneOdio
- OnePlus
- onix
- ONKYO
- ONVEIL
- ONYX（Ringke）
- OPAQUE.CLIP
- opera（トキナー）
- OPPO
- OPPO A
- Opteka
- Opti-myst
- Optiflame
- OptiPlex
- OPUS BEAUTY
- orage
- ORAQLE