| One Step Beyond Flooring Wholesale Ltd | Mitcham | A rating |
| ONE STEP DESIGN&PRINT LTD | London | A rating |
| One Step Retail Ltd | Lancashire | A rating |
| One Stop | Rochdale | A rating |
| ONE STOP | LONDON | A rating |
| One Stop Auto Repair and Sales Ltd | Littleborough | A rating |
| One Stop Barleythorpe | Oakham | A rating |
| ONE STOP BUILDERS MERCHANTS (ENFIELD) LTD | Enfield | A rating |
| ONE STOP CAR CLINIC LTD | BRADFORD | A rating |
| One Stop Care Ltd | Nottingham | A rating |
| One Stop Chai Ltd | Leicester | A rating |
| One Stop Convenience Store | Leicester | A rating |
| One Stop Darfield | Darfield Barnsley | A rating |
| ONE STOP DEALERS LIMITED | Leicester | A rating |
| One Stop Express Ltd | London | A rating |
| One Stop Halal Meat Centre Limited TA One Stop Halal Meat Centre | Birmingham | A rating |
| One Stop Healthcare | Hemel Hempstead | A rating |
| One Stop Kph Traders | Telford | A rating |
| ONE STOP LAWRENCE ROAD LTD | Liverpool | A rating |
| ONE STOP NORTH LONDON LTD | RAYLEIGH | A rating |
| One Stop Phone Solution Ltd T/AS Sunny Phones and Computers | Sheffield | A rating |
| ONE STOP RECYCLING NW LTD | Preston | A rating |
| ONE STOP SECURE LTD | Barking | A rating |
| One Stop Service Point Ltd | London | A rating |
| ONE STOP SHADSWORTH | BLACKBURN | A rating |
| One Stop Shipping Ltd | Rainham | A rating |
| ONE STOP SHOP FITTINGS LTD | MANCHESTER | A rating |
| One Stop Smallthorne | Stoke on Trent | A rating |
| ONE STOP SOLUTION | Hounslow | A rating |
| One Stop T/A Rani Stores | Ashford,Kent | A rating |
| ONE STOP TRAVEL LTD | BOLTON | A rating |
| ONE STRATEGY GROUP UK LTD | London | A rating |
| One to All Limited | Westhoughton | A rating |
| One Trading Exchange BV London Branch | London | A rating |
| One Tribe TV Ltd | Bath | A rating |
| One UK Trading Ltd | Surrey | A rating |
| ONE UMMAH AYLESBURY LTD | Aylesbury | A rating |
| One Utility Bill Limited | NEWCASTLE UPON TYNE | A rating |
| One Voice Consulting Limited | Wokingham | A rating |
| One Vyner Street Limited | London | A rating |
| One Westminster | London | A rating |
| One Works S.P.A | London | A rating |
| One World Commodities Ltd | Beckenham | A rating |
| One World Information Service Limited | London | A rating |
| One World Realty Ltd | Manchester | A rating |
| One World Travel Services Limited | Slough | A rating |
| One YMCA | Watford | A rating |
| One Young World Limited | London | A rating |
| One.io Services Limited | London | A rating |
| One1000 Ltd | Shepperton | A rating |
| One4M Ltd | Croydon | A rating |
| ONEAFFINITI LTD | Bracknell | A rating |
| ONEAFRICA TECHNOLOGIES LTD | MANCHESTER | A rating |
| ONEAPPS ENTERPRISE TECHNOLOGIES LTD | Sutton | A rating |
| Onebeyond Retail Limited | Barnsley | A rating |
| Onebite Limited | London | A rating |
| Onebright Ltd | York | A rating |
| Onebrother Private Limited | Manchester | A rating |
| Onecall.com Ltd | London | A rating |
| ONECARE HAMPSHIRE LIMITED | Southampton | A rating |
| Onecare- UK Ltd | South Harrow | A rating |
| OneChronos Markets UK Limited | London | A rating |
| Onedayone Fruit Uk Ltd | Suffolk | A rating |
| OneDome Ltd | London | A rating |
| Onee Travel Services Limited | Maidenhead | A rating |
| Onefootball UK Limited | London | A rating |
| Oneglobal Broking Services Limited | London | A rating |
| Oneio Cloud UK Limited | London | A rating |
| ONEIRIC HUB LTD | London | A rating |
| Onelaw Limited t/a OneLaw Chambers | London | A rating |
| Onelife Healthcare Ltd | Bradford | A rating |
| Onelivery Ltd | London | A rating |
| OneMedicare LTD | Leeds | A rating |
| Onepiece Jump in Ltd | London | A rating |
| Oneplace Homes Ltd | Chatham | A rating |
| Oner Active UK ltd | London | A rating |
| ONESA PARTNERS UK LIMITED | London | A rating |
| OneSavings Bank plc | Chatham | A rating |
| ONESCENE LTD | London | A rating |
| Oneseat Ltd | OXON | A rating |
| Oneshot.ai Limited | Gerrards Cross | A rating |
| ONESMARTCLICK LTD T/A Ques Pizza | Newcastle upon Tyne | A rating |
| OneSpan Solutions UK Limited | Cambridge | A rating |
| OneSpirit Interfaith Foundation | Warrington | A rating |
| OneStock Software Ltd | London | A rating |
| OneSubsea UK Limited | Leeds | A rating |
| Onetag | London | A rating |
| Oneteam Motors Limited | Grays | A rating |
| ONETECHUK LTD | BIRMINGHAM | A rating |
| Onetrace Ltd | London | A rating |
| OneTrust Technology Limited | London | A rating |
| Onevoice Digital Limited | Manchester | A rating |
| ONEWIG ONESMILE Limited | Chatham | A rating |
| ONEWORLD PVT LTD | Harrow | A rating |
| Onex Partners Advisor UK LLP | London | A rating |
| Onex Sport Limited | Manchester | A rating |
| Onfido Ltd | London | A rating |
| Ongar Health Centre | Ongar | A rating |
| ONGAR POST OFFICE | ONGAR | A rating |
| ONGARMART | LEICESTER | A rating |
| ONGARMART LTD | Leicester | A rating |
| ONGEA CREATIVE LIMITED | LONDON | A rating |
| OnGen Ltd | Edinburgh | A rating |
| OniGroup EMEA Limited | London | A rating |
| ONION BHAJI INDIAN LTD | SUDBURY | A rating |
| Onis Legal Services Ltd | BRISTOL | A rating |
| Onix Solutions Limited | London | A rating |
| ONKA UK ELECTRICAL LTD | London | A rating |
| ONKAR BUILDERS LTD | Slough | A rating |
| ONKO | Cobham | A rating |
| Onkohealth Ltd | London | A rating |
| ONLINE 24/7 LTD | Corringham | A rating |
| Online Account Filing Limited | London | A rating |
| ONLINE ACCOUNTANT LTD | London | A rating |
| Online Art School Ltd | Danbury | A rating |
| Online Business School Limited | Coventry | A rating |
| Online Cables (Scotland) Limited | Aberdeen | A rating |
| Online Filings Ltd | London | A rating |
| Online Heaven Ltd | EDINBURGH | A rating |
| ONLINE HOME SHOP LIMITED | Manchester | A rating |
| Online Intergrated Solutions Limited | London | A rating |
| Online Oceans Robotics Limited | Christchurch | A rating |
| ONLINE ONLINE LIMITED | Croydon | A rating |
| Online Retail Services Limited | Southall | A rating |
| Online Traderz UK Limited | Glasgow | A rating |
| ONLINE TRANSPORT LIMITED | BIRMINGHAM | A rating |
| Online Venture Partners Limited | Rayleigh | A rating |
| Online Wellness Limited | Edgware | A rating |
| ONLINEAMZ LTD T/A RISH EXPRESS | HERTFORDSHIRE | A rating |
| ONLY 1 KASHMIR LTD | Canterbury | A rating |
| ONLY BUSINESS SERVICES LTD | St Albans | A rating |
| Only Care Limited | North Harrow | A rating |
| Only Connect UK | London | A rating |
| Only Helix Ltd | London | A rating |
| ONLY LOCAL EXPRESS LIMITED | London | A rating |
| ONLY LOVE BEAUTY LIMITED | London | A rating |
| Only the Brave Group Limited | Birdham | A rating |
| Onlyus Enterprises UK Limited | Oxford | A rating |
| ONNEC Group UK Limited | London | A rating |
| ONNU LTD | Bury St Edmunds | A rating |
| ONNY COTTAGE RESIDENTIAL CARE HOME | LUDLOW | A rating |
| ONO PHARMA UK LTD | London | A rating |
| ONOSOM DISTRIBUTION LIMITED | Barnsley | A rating |
| ONPOINT TRADING LTD | Bolton | A rating |
| ONSB LTD T/A LEATHERHEAD POST OFFICE | LEATHERHEAD | A rating |
| ONSECURITY TECHNOLOGY LIMITED | Bristol | A rating |
| ONSET GLOBAL TRADING UK LTD | London | A rating |
| OnSite Support Ltd | Crawley | A rating |
| Onstate Limited | Leeds | A rating |
| OnStream Group Limited | Essex | A rating |
| ONTARIO TEACHERS' PENSION PLAN (EUROPE) LIMITED | LONDON | A rating |
| Ontario Teachers' Pension Plan (Europe) RE Limited | London | A rating |
| ONTEX HEALTHCARE UK LIMITED | Corby | A rating |
| Ontic Engineering and Manufacturing UK Ltd | Cheltenham | A rating |
| Ontier Holdings Ltd | London | A rating |
| Ontik Technologies Limited | London | A rating |
| Ontime Accountancy Practice Ltd | Gravesend | A rating |
| ONTIME BUSINESS SOLUTIONS LTD | Bradford | A rating |
| ONTIME CARGO LIMITED | London | A rating |
| ONTIME CARS LTD | CANTERBURY | A rating |
| ONTIME CONCRETE LTD | Hayes | A rating |
| Ontime Gas and Heating Limited | Birmingham | A rating |
| ONTIME HEATING AND PLUMBING LTD | Birmingham | A rating |
| ONTIME PLUMBERS LTD | LONDON | A rating |
| Ontime Response Healthcare Limited | KING'S LYNN | A rating |
| ONTINUE UK LTD | Birmingham | A rating |
| Ontology Partners Limited | Dalkeith | A rating |
| Ontra Healthcare Ltd | Slough | A rating |
| ONTRAX EQUIPMENT LTD | Coleraine | A rating |
| Ontro Ltd | London | A rating |
| ONUBAFRUIT UK LIMITED | Maidstone | A rating |
| Onunda Limited | Carlisle | A rating |
| ONVU TECHNOLOGIES LIMITED | LONDON | A rating |
| Onward Hire Ltd | Walsall | A rating |
| Onward Technologies Ltd | Birmingham | A rating |
| ONWAY LDD LTD | Reading | A rating |
| Onyx Commodities Ltd | London | A rating |
| ONYX HAULAGE LIMITED | Hounslow | A rating |
| Onyx Health | Newcastle upon Tyne | A rating |
| Onyx Living Ltd | Manchester | A rating |
| ONYX PRODUCTIONS LTD | Glasgow | A rating |
| Onzo (St Ives) Limited | St Ives | A rating |
| Oobasi Ltd | Borehamwood | A rating |
| OOBE Ltd | Newcastle upon Tyne | A rating |
| OOCL UK Branch | Ipswich | A rating |
| Oodle Financial Services Limited | Manchester | A rating |
| Oodles Chinese Holdings Ltd | Leicester | A rating |
| OODSUL LIMITED | London | A rating |
| OOJ HOMECARE SERVICES | LEEDS | A rating |
| OOJ HOMECARE SERVICES LTD | LEEDS | A rating |
| Oolio Group UK Ltd | Warrington | A rating |
| oomph Agency Services Ltd | Llanarth | A rating |
| OONAGI TRADING LIMITED | Wanstead | A rating |
| Ooni Limited | Broxburn | A rating |
| Ooooby UK Limited | Totnes | A rating |
| Ooops! Automotive Ltd | Poole | A rating |
| Oort Energy Ltd | Bristol | A rating |
| OOTTUPURA EWELL LTD | SURREY | A rating |
| Ooviya Limited | Northolt | A rating |
| OP Dental Ltd | Bretton | A rating |