| OCEANS EDGE RESTAURANT LIMITED | Holyhead | A rating |
| Oceans Spas Limited | Newbury | A rating |
| Oceans Travel Ltd | Derby | A rating |
| Oceanside Logistics LTD | SOUTHAMPTON | A rating |
| Oceanus Restaurant Limited | Boness | A rating |
| Oceanus Swim Limited | London | A rating |
| OCEANWAY CARE LTD | Birmingham | A rating |
| OceanWise Limited | Alton | A rating |
| Oceonix Services Limited | London | A rating |
| OCF SOLUTIONS LTD | omagh | A rating |
| Ochil Tower School | Auchterarder | A rating |
| OCHILTREE STORES LTD | Scotland | A rating |
| Ochre Bio | Oxford | A rating |
| OCHRE RIVINGTON LIMITED T/A OCHRE RIVINGTON SERVICES | London | A rating |
| OCHS TRADING MARKET LTD | Orpington | A rating |
| OCI Foundation UK | KNOTTY ASH | A rating |
| OCI Limited | London | A rating |
| OCI NITROGEN (UK) LTD | London | A rating |
| Ocimum Healthcare Ltd | Luton | A rating |
| Ockbrook & Borrowash Cricket Club | Derby | A rating |
| Ockham's Razor | London | A rating |
| Ockwells Manor Ltd | Maidenhead | A rating |
| OCL London Ltd | London | A rating |
| OCLC (UK) Limited | Sheffield | A rating |
| OCO Digitals Ltd | London | A rating |
| OCO Global Limited | Belfast | A rating |
| Ocorian Services (UK) Ltd | London | A rating |
| OCR Alpha | London | A rating |
| OCS Consulting plc | Borehamwood | A rating |
| Octa Fire Ltd | London | A rating |
| Octagon I/O Ltd | London | A rating |
| OctaiPipe Limited | London | A rating |
| Octane Capital Limited | London | A rating |
| Octane Holding Group Ltd | Bradford | A rating |
| Octave Services Limited | London | A rating |
| Octavia House Dental Practice | Godalming | A rating |
| Octavian Facilities Management Ltd | Bingham | A rating |
| Octavian Healthcare Limited | Manchester | A rating |
| Octavius Infrastructure Limited | Reigate | A rating |
| Octispace Limited | London | A rating |
| Octo Telematics UK Limited | London | A rating |
| October Gallery Trust | London | A rating |
| October Store Ltd. | London | A rating |
| Octobreeze Ltd | Birmingham | A rating |
| Octophin Digital Limited | London | A rating |
| Octopreneur Intelligence Limited | Bristol | A rating |
| Octopus Capital Limited | London | A rating |
| Octopus Energy Limited | London | A rating |
| Octopus Inc Ltd | London | A rating |
| Octus Intelligence Limited | London | A rating |
| OCU Modus Ltd | GREENWICH | A rating |
| OCU NETTWORX LIMITED | Omagh | A rating |
| OCU Services Limited | Stockport | A rating |
| Ocubis Limited | London | A rating |
| Ocula Technologies Limited | Barnes | A rating |
| OCULAS INSTALLATION LTD | Croydon | A rating |
| Oculo Technologies Ltd | London | A rating |
| OCURENS LTD | London | A rating |
| OCUWELL Limited | LIVERPOOL | A rating |
| OCZO LLP | London | A rating |
| OD Accountants Ltd | London | A rating |
| OD PR Limited | London | A rating |
| OD PROJECTS (HOLDINGS) LTD | London | A rating |
| OD3 BIM | Antrim | A rating |
| ODA IMPORTS LTD | BIRMINGHAM | A rating |
| ODA UK Studio Limited | London | A rating |
| Odai Limited | Hertford | A rating |
| ODAK UK LTD | London | A rating |
| Odara Care | Hexham | A rating |
| Oddball Motion Pictures (UK) Limited | United Kingdom | A rating |
| Oddlygood UK Ltd | London | A rating |
| ODDO BHF UK LIMITED | London | A rating |
| Oddono's Gelati Italiani Ltd | London | A rating |
| ODE Asset Management Limited | Great Yarmouth | A rating |
| Ode to Joy Flowers Co. Ltd | Stamford | A rating |
| Odeko (N.I.) Ltd | Hillingdon | A rating |
| Odeon Cinemas Limited | London | A rating |
| Odera Services Limited | Belvedere | A rating |
| Odessa Private Limited | London | A rating |
| Odevo UK Limited | London | A rating |
| Odey Asset Management LLP | London | A rating |
| Odfjell Drilling Ltd | Aberdeen | A rating |
| Odfjell Technology (UK) Ltd | Aberdeen | A rating |
| Odfjell Technology Ltd | Aberdeen | A rating |
| ODG Construction, Ltd. | Petts Wood | A rating |
| Odhin limited | London | A rating |
| ODI Global | London | A rating |
| Odin Medical Ltd | London | A rating |
| Odin Partners Limited | London | A rating |
| ODIN PARTNERSHIP LIMITED | London | A rating |
| Odisseo Enterprise Ltd trading as The Coffee Room | London | A rating |
| ODL EUROPE LTD | BOOTLE | A rating |
| ODM Restaurants Ltd | Coleraine | A rating |
| ODM Seeds, Tithes & Gifts Ltd | Kent | A rating |
| Odonto Ltd T/a Cathedral Dental Clinic | Cardiff | A rating |
| ODOS PROPERTIES LTD | Newent | A rating |
| Odqa Renewable Energy Technologies Limited | Oxford | A rating |
| Odro Ltd | Glasgow | A rating |
| ODYN BROTHERS COV LIMITED | Coventry | A rating |
| ODYSSEY (G.B) LIMITED | Rochdale | A rating |
| Odyssey Capital Management Limited | London | A rating |
| Odyssey Computing Limited | London | A rating |
| Odyssey Dining Limited | London | A rating |
| ODYSSEY EDUCATION SERVICES LIMITED | Bracknell | A rating |
| Odyssey Interactive Limited | Manchester | A rating |
| Odyssey MM Group | Nottingham | A rating |
| Odyssey Therapeutics UK Limited | Kettering | A rating |
| OE Electrics Ltd | Wakefield | A rating |
| OE QORBAN CONSULT LIMITED | NETHER POPPLETON | A rating |
| OE TECHNOLOGY LTD | Cambridge | A rating |
| OEA Global Ltd | St Albans | A rating |
| OEE Container Technology Limited | Carlisle | A rating |
| OEG MARINE LIMITED | Great Yarmouth | A rating |
| OEG Renewables Group Limited | Great Yarmouth | A rating |
| Oek Fabrications Limited | London | A rating |
| OEM - Automatic Limited | Whetstone | A rating |
| Oenofuture Limited | London | A rating |
| OES CONSULTING CIVILS LIMITED | Dudley | A rating |
| OES Engineering Solutions Ltd | Dungannon | A rating |
| OES OILFIELD SERVICES (UK) LIMITED | Stockton-On-Tees | A rating |
| Of Architecture Limited | London | A rating |
| OF ENTERPRISES LTD | Romford | A rating |
| Ofcom | London | A rating |
| Ofer Investments LTD | London | A rating |
| Off Licence Truro Malabar Convenience Store | Truro | A rating |
| Off Site Solutions (R T) Limited | Highbridge | A rating |
| Off The Kerb Productions Ltd | London | A rating |
| Off the Rock Design Ltd | EDINBURGH | A rating |
| Off-Piste Wines Limited | Cheltenham | A rating |
| OFFA OPERATIONS LTD | SOLIHULL | A rating |
| Offbeat Fashion Ltd | London | A rating |
| Offenham Village Stores Ltd | Offenham | A rating |
| Offer Plus Ltd | London | A rating |
| Offer4uni LTD | Leicester | A rating |
| Offgrid Energy Labs Limited | Bexley | A rating |
| Office 21 Ltd | West Wickham | A rating |
| Office Athletes (Cambridge) Limited | Cambridge | A rating |
| Office for National Statistics | Newport | A rating |
| Office for Nuclear Regulation | Liverpool | A rating |
| Office Holdings Limited | London | A rating |
| Office of Agent-General for Victoria | London | A rating |
| Office of Design, Architecture & Consultant Engineers Ltd | London | A rating |
| Office of Gas and Electricity Markets | London | A rating |
| Office Of Rail and Road | London | A rating |
| Office of the Agent General | London | A rating |
| Office of the Free State of Bavaria in the United Kingdom | London | A rating |
| Office Oracle Group Limited | Dartford | A rating |
| Office Space Cleaning Limited | Northants | A rating |
| Office Space in Town Ltd | Corby | A rating |
| Officeology Ltd | London | A rating |
| OFFICERND LIMITED | North Shields | A rating |
| Official Watches Limited | London | A rating |
| Officine Inernational Ltd | LONDON | A rating |
| Offington Park Limited T/A Offington Park Care Home | Worthing | A rating |
| Offroad Games Ltd | London | A rating |
| OFFSET PRINT & PACKAGING LIMITED | Aylesford | A rating |
| OFFSHORE CONSTRUCTION CONSULTANTS LIMITED | London | A rating |
| Offshore Helicopter Services UK Limited | Aberdeen | A rating |
| Offshore Renewable Energy Catapult | Glasgow | A rating |
| Offshore Turbine Services | Brixham | A rating |
| Offshore Water Management Ltd | Westhill | A rating |
| Offspring Films Limited | Bristol | A rating |
| OFLOX LTD | London | A rating |
| OFORI HAMMOND LTD | Twickenham | A rating |
| OFR Consultants Limited | Manchester | A rating |
| OFS Fitel UK Ltd | Llantarnum | A rating |
| Ofsted | London | A rating |
| OG COLLECTIONS LTD | St Albans | A rating |
| Ogab Limited | Hertfordshire | A rating |
| Ogababa Limited | London | A rating |
| OGAM LTD | London | A rating |
| Ogbonna Properties | Cardiff | A rating |
| OGC Energy Ltd | Sheffield | A rating |
| OGCI Climate Investments LLP | London | A rating |
| OGCI Limited | London | A rating |
| OGCS Global Limited | Weybridge | A rating |
| OGGI LTD | Leicester | A rating |
| Oghma Partners LLP | London | A rating |
| OGI Groundwater Specialists Ltd | Durham | A rating |
| Ogier Global (UK) Limited | London | A rating |
| Ogilvy & Mathers Group (Holdings) Limited | London | A rating |
| OGL Advisors Limited | London | A rating |
| Ogletree Deakins LLP | London | A rating |
| Ogma Therapy Ltd | London | A rating |
| OGMORE VALLEY FAMILY DENTAL PRACTICE | Bridgend | A rating |
| OGMORE VALLEY STORE LTD | Bridgend | A rating |
| Ognisko Restaurant Ltd | London | A rating |
| OGS Mechanics Keys Ltd | London | A rating |
| OGS Mechanics Ltd | London | A rating |
| Ogury Ltd | London | A rating |
| Ogwell Grange Limited | Newton Abbot | A rating |
| OGZ Desserts Ltd | Birmingham | A rating |
| Oh Baby Ultrasound LTD | Ballymena | A rating |
| OH Dental Limited | headcorn | A rating |
| Oh Goodlord Ltd | London | A rating |
| OH PAPI LTD | LIMAVADY | A rating |
| Oh Polly Ltd | Wirral | A rating |
| OH&M LTD | Madden | A rating |
| OHAANA HALAL CHINESE LTD T/A Ohaana Authentic Chinese | Buckinghamshire | A rating |
| Ohalo Limited | London | A rating |