- Oddbins
- OneStopPhoneShop
- Otherland Toys
- Old English Inns
- Origins UK
- Off Peak Luxury
- Optimax
- Outdoor World Direct
- O'Neills
- Ollie & Nic
- Overclockers
- Outdoorkit.co.uk
- Omlet
- OutdoorGB
- Oi Polloi
- Outside UK
- Original Organics
- Onestop-digital.com
- O2 Mobile Broadband Pay Monthly
- Optics Planet
- OnePiece
- Orlando Ticket Deals
- Owners Direct
- Oh My Love
- Oasis Home and Hobby
- Oliver Bonas
- Office Furniture
- OKA Direct
- Opodo
- OnlineGolf
- Office Shoes
- Ocado
- Oasis
- Oak Furniture Land
- Optimum Nutrition
- One Garden
- OASAP
- Original Dating
- OutdoorGear UK
- Oki-ni
- Orvis
- Orchira
- Outdoor Megastore
- OfferX
- Origin by EA Store
- One.com
- Office Stationery
- OnPole
- Oxfam Shop
- Oak Furniture Solutions
- OverNight Prints
- Ordnance Survey Leisure Map Shop
- Otel.com
- Ocean Lighting
- O'Neill
- Offspring Shoes
- Organic Bouquet
- O2 recycle
- Order Blinds
- Organic Surge
- Onyx Hospitality Group
- Onhotels.com
- Old Navy
- Outdoor Look
- O & O Software
- Original Penguin
- Oak Furniture Superstore
- Original Resorts
- Oak World
- Oxygen Boutique
- OutdoorCanvas.co.uk
- Oak Furniture King
- OnePlay
- Ottillie Pop
- Orelia
- Only Home
- OUL Direct
- OneTravel
- Only Natural Pet
- Office Depot