O Stores
- Oak Essentials
- Oakley
- Oakley AUS
- Oakley Brazil
- Oakley Standard Issue
- Objekts
- Octa Markets LTD
- Octopart
- OCU-ROI UP
- Office Depot
- OfficeFurniture2Go
- Officine Generale Global
- OH LA LAQUA
- Oklahoma Joe's
- Olay
- Olive Ateliers
- Ollie
- Omio Travel GmbH
- OM SYSTEM
- OnBuy.com
- One.com
- One.com USA
- OneTeaspoon
- OneTravel
- Online Cigars
- Only Natural Pet
- Onsen
- Oojo
- O&O Software
- Opencare
- Open Spaces
- Optimum Nutrition
- Oracle Red Bull Racing eScooter
- Orbitz
- O'Reilly
- Orgain
- Organic Baby Food
- Origin PC
- OrlandoVacation.com
- OrnamentShop.com
- ortorex.com global
- Osmo Salt
- OtterBox
- Ourtime [Match.com]
- Outcast Clothing
- OVAGO
- Overland Sheepskin Co.
- Overstock