| U & H Delight LTD | Rochdale | A rating |
| U & I Fuels Ltd | Oxford | A rating |
| U & K LIMITED | London | A rating |
| U & N Stores Ltd | Glasgow | A rating |
| U & R SERVICES LTD | Birmingham | A rating |
| U & T Services Ltd | Burnley | A rating |
| U & T STARTS SERVICES LTD | Bristol | A rating |
| U 4 Utility Ltd | London | A rating |
| U AND A AUTO REPAIR CENTRE LTD | Manchester | A rating |
| U BREAK WE FIX (HEREFORD) LIMITED | Hereford | A rating |
| U Can Fly Ltd T/A Lycafly | London | A rating |
| U Energy (Yorkshire) Limited | Huddersfield | A rating |
| U I A TRADING LTD | Manchester | A rating |
| U In Mind Care Limited | Ipswich | A rating |
| U K BUILDERS (TT) LTD | Hayes | A rating |
| U KITCHEN EXPRESS LTD | Bolton | A rating |
| U L Consultants Limited | Edgware | A rating |
| U LOCAL LIMITED | Bangor | A rating |
| U M STORES (LONDIS) | LONDON | A rating |
| U MATTER LTD | Clarence Road | A rating |
| U R DERDER TRAVEL LTD | Sutton | A rating |
| U R Secure Limited | Luton | A rating |
| U Sea Fishing Limited | London | A rating |
| U Stores Aberdeen Limited | Aberdeen | A rating |
| U TEA LIMITED | London | A rating |
| U Travel 350 LTD | Blackburn | A rating |
| U VALUE ACCOUNTANTS LTD | Erith | A rating |
| U VALUE FACILITIES LIMITED | Erith | A rating |
| u-Blox Cambridge Limited | Cambridge | A rating |
| u-Blox Luton Limited | Cambridge | A rating |
| U-Chem Private Limited | Altrincham | A rating |
| U-Designservices Ltd. | CITY ROAD | A rating |
| U-Earth Biotech Ltd | London | A rating |
| U-Ploid Biotechnologies ltd. | Oxford | A rating |
| U.Bhula Limited | Bolton | A rating |
| U.I GROUP LIMITED T/A U CARZ | NORWICH | A rating |
| U.K BOYUAN INTERNATIONAL LIMITED | London | A rating |
| U.K. Implant Manufacturing Co. Limited | Dunstable | A rating |
| U.K. MASSALA MIX LIMITED T/a Maya Restaurant | Atherstone | A rating |
| U.P Store | Stoke On Trent | A rating |
| U.S. Bank Europe DAC | London | A rating |
| U.Z.A.K TRADING LIMITED | Glasgow | A rating |
| U&A CONNEXION | MANCHESTER | A rating |
| U&I Care Limited | Warrington | A rating |
| U&I UK Retail Ltd | Glossop | A rating |
| U&S Clothing LTD | Bolton | A rating |
| U&S ENTERPRISES LIMITED | Accrington | A rating |
| U&S LIMITED T/A Subway | Giffnock, Glasgow | A rating |
| U&S PARTNERS LTD | Birmingham | A rating |
| U&Z HEALTHCARE LTD TA BAGULEY PHARMACY | Manchester | A rating |
| U58 CONSTRUCTION LTD | London | A rating |
| UA BRANDS LTD | Birmingham | A rating |
| UA CONSTRUCTION LTD | SOUTHALL | A rating |
| UAA Fish Limited T/A Seven Seas Fish and Chips | Lancashire | A rating |
| Uaap Trading Limited | Glasgow | A rating |
| UAB IT Services Ltd | Reading | A rating |
| UACB EDUCATION | Birmingham | A rating |
| UAE Polo Team | Midhurst | A rating |
| UAL ARTSTEMPS LTD | LONDON | A rating |
| UAN Ltd (UAN Chartered Certified Accountants) | Canary Wharf | A rating |
| UAO FINANCIALS LTD | NECASTLE UPON TYNE | A rating |
| Uart Studio Limited | London | A rating |
| UAV Tactical Systems Limited | Leicester | A rating |
| UAVICTOR AEROSPACE LTD | Harrow | A rating |
| UB Foods Ltd T/A Afrikana Ilford | Ilford | A rating |
| UB Plastics Limited | Burton Upon Trent | A rating |
| UB Solution & Edulink Limited | London | A rating |
| UB1 Construction Services Ltd | Southall | A rating |
| UB2 TILES LTD | London | A rating |
| UBDS IT CONSULTING LTD | Tunbridge Wells | A rating |
| UBEAUTY CLINIC LTD | Nottingham | A rating |
| Uber and Beyond Ltd | Northampton | A rating |
| Uber Contracts Ltd | Sunbury on Thames | A rating |
| Uber Eats UK Limited | London | A rating |
| Uber Interiors Limited | Cheshire | A rating |
| Uber London Limited | London | A rating |
| Uber Payroll Ltd | Surrey | A rating |
| Uberbinder Limited | Oxford | A rating |
| UBERPLAS LTD | LONDON | A rating |
| Ubertas Care Homes Limited | Leicester | A rating |
| UBG Corporation Limited | London | A rating |
| UBH Manchester Ltd T/A Hotel Indigo Manchester - Victoria Station | Manchester | A rating |
| UBI Courtage Limited | Tunbridge Wells | A rating |
| UBIETY Technologies Limited | Ely | A rating |
| UbiPOS UK Limited | London | A rating |
| UBIQUE DIGITAL LTD | London | A rating |
| Ubique Legal Limited | Redditch | A rating |
| UBIQUE SYSTEMS UK LIMITED | LONDON | A rating |
| Ubiquiti Distribution UK Limited | London | A rating |
| Ubiqutek Ltd | Kineton | A rating |
| Ubisense Limited | Cambridge | A rating |
| Ubisoft Reflections Ltd | Gosforth | A rating |
| ubitricity Distributed Energy Systems UK Ltd | London | A rating |
| UBON (UK) LTD | Manchester | A rating |
| UBREAKIFIXX LTD | London | A rating |
| UBS AG | London | A rating |
| UBT (EU) Ltd | Warwick | A rating |
| Ubuntu Advisory and Investments Limited | London | A rating |
| UBUNTU GROUP LIMITED | WELLINGTON | A rating |
| Ubuntu Pathways | London | A rating |
| UC ELEGANCE LTD | Ruislip | A rating |
| UC FOODS LTD | London | A rating |
| UC TRADE LIMITED | London | A rating |
| UC WORLD-LINK LOGISTIC AND DISTRIBUTION LTD | Blackburn | A rating |
| UCAK LIMITED | Thornton Heath | A rating |
| Ucan Care Ltd | Aberdare | A rating |
| UCAN CONSULTING LTD | London | A rating |
| UCB S.A. and UCB Celltech | Slough | A rating |
| UCC Europe Limited | Ealing | A rating |
| UCC London Ltd | Manchester | A rating |
| Uccelli UK Ltd | Egham | A rating |
| UCEA Capital Partners Limited | London | A rating |
| UCH Logistics Limited | Slough | A rating |
| Uchimura UK. Ltd | Co. Durham | A rating |
| Uckfield Specsavers Limited T/A Specsavers Opticians | Uckfield | A rating |
| UCKG HELPCENTRE | LONDON | A rating |
| UCL Business Ltd | London | A rating |
| UCL Consultants Ltd | London | A rating |
| UCL ENERGY GROUP LIMITED | London | A rating |
| UCL SWIFT LTD | London | A rating |
| UCLEAN DRY CLEANERS LIMITED | Bolton | A rating |
| UCM (Global) Limited | Ipswich | A rating |
| UCON Construction Limited | London | A rating |
| UCPC Ltd | Milton Keynes | A rating |
| UCR Integrations Ltd | Southampton | A rating |
| ucreate Limited | London | A rating |
| UCS Renewables Ltd | Middlesbrough | A rating |
| UCSS Ltd | Stirling | A rating |
| UD Greenway Ltd | Ellesmere Port | A rating |
| UD Restaurants Limited | London | A rating |
| UD Software Solutions Group Limited | Manchester | A rating |
| UDAIPUR RESTAURANT | London | A rating |
| Uday & Partap Enterprises Limited | Swansea | A rating |
| Uday's Restaurant Ltd T/A Uday's Indian restaurant | Wolverhampton | A rating |
| Udaya Foods Ltd | Romford | A rating |
| Uddin Learning Solution UK Ltd | London | A rating |
| UDDINGSTON CONVENIENCE STORE LTD t/a USAVE | Glasgow | A rating |
| Uddingston Cricket and Sports Club | Uddingston | A rating |
| Uddingston Physiotherapy & Rehabilitation Clinic | Glasgow | A rating |
| UDELIVER LTD | CHATHAM | A rating |
| UDICHI SHILPI GOSTHI | London | A rating |
| UDLIVE LIMITED | ALTON | A rating |
| UDO Audio LTD | Bristol | A rating |
| Udyog Mandir Pvt Ltd | Harrow | A rating |
| UE Group Ltd | Corby | A rating |
| UEES LTD T/A SMOKIN GRILL STEAKHOUSE AND BAR | WORCESTER PARK | A rating |
| UENI Limited | London | A rating |
| UENS UK LIMITED | STAINES UPON THAMES | A rating |
| Uevolve Healthcare UK Ltd | London | A rating |
| UF01 LTD | Glasgow | A rating |
| UF02 LTD | Blairgowrie | A rating |
| UF03 LTD | Dundee | A rating |
| UFA Marketplace Limited | Liverpool | A rating |
| UFFIZZI RESTAURANT LTD | LONDON | A rating |
| Ufford Park Limited | Suffolk | A rating |
| Ufix LIMITED | Ilford | A rating |
| UFK TRADING LTD. | PRESTON | A rating |
| Uflex Europe Limited | London | A rating |
| Ufone Direct | Bradford | A rating |
| Ufonia Ltd | Oxford | A rating |
| UForce Trading Ltd | London | A rating |
| UFP London Limited | London | A rating |
| UG TRADE LTD | Manchester | A rating |
| UG World LTD | London | A rating |
| UGANDA CROYDON CATHOLIC COMMUNITY (UCCC) | Croydon | A rating |
| UGE DENT LTD | LONDON | A rating |
| Uggeshall Farms | Beccles | A rating |
| Ugo Foods Group | Borehamwood | A rating |
| UGT WORLD TRADING LTD | London | A rating |
| UH FAST FOOD UK LTD | Birmingham | A rating |
| Uh K-Dogs n Juicy Ltd | London | A rating |
| UHD LIMITED | Glasgow | A rating |
| UHH Limited | Moray | A rating |
| UHI North, West & Hebrides | THURSO | A rating |
| UHI Shetland | Lerwick | A rating |
| Uhlmann U.K. Limited | Sandhurst | A rating |
| Uhmaar Limited | Sutton | A rating |
| UHOMES.COM UK CO., LTD. | London | A rating |
| UHS Estates Limited | Southampton | A rating |
| UHY Calvert Smith LLP | York | A rating |
| UHY Hacker Young | Hove | A rating |
| UHY Hacker Young LLP | London | A rating |
| UIA Fashion Ltd | Middelton | A rating |
| UIC Digital Ltd | London | A rating |
| Uig Pottery Ltd | Uig | A rating |
| Uinsure Limited | Manchester | A rating |
| UIPATH UK LIMITED | LONDON | A rating |
| UIRTUS CONSTRUCTION LTD | Huddersfield | A rating |
| Uist Asco Limited | Isle of North Uist | A rating |
| UJAAS DESSERT LIMITED | Norwich | A rating |
| Ujaas Health Ltd | Dereham | A rating |
| UJAN BHAT CASH & CARRY LIMITED | LUTON | A rating |
| Ujan Vati | Oldham | A rating |
| Ujari Merchant Ltd | London | A rating |
| Ujima Ltd | Waterlooville | A rating |
| UJNG Limited | London | A rating |
| UK & IRELAND 2028 LIMITED | London | A rating |
| UK 1 Services Ltd | Bradford | A rating |
| UK Academics and Guardianship Ltd | Bedford | A rating |
| UK ACCOUNTS & TAX LTD | Crawley | A rating |