| X & WHY LIMITED | London, England | A rating |
| X and L Limited | Fort William | A rating |
| X CLUB LIMITED | London | A rating |
| X Cyber Group Ltd | Cloucester | A rating |
| X D P Limited | Sutton Coldfield | A rating |
| X Facilities Group Limited | Stanmore | A rating |
| X Infinity Group Ltd T/A X Infinity Group | Liverpool | A rating |
| X Law Ltd | Manchester | A rating |
| X PROMPT LTD | Slough | A rating |
| X R Games Limited | Leeds | A rating |
| X TERRACE FASHION LTD | Bishops Stortford | A rating |
| X-Aces Consultancy Limited | Basingstoke | A rating |
| X-Act IT Ltd | Redruth | A rating |
| X-Edit Limited (trading as EditShare) | Basingstoke | A rating |
| X-Flow II Ltd | Leatherhead | A rating |
| X-Pharm Limited | Berkshire | A rating |
| X-Press Container Line (UK) Limited | Southampton | A rating |
| X-R Touring LLP | London | A rating |
| X-Rite Ltd. | Stockport | A rating |
| X.AI LONDON LTD | London | A rating |
| X1 Property Management LTD | Salford | A rating |
| X1F UK Limited | London | A rating |
| X2X Limited | London | A rating |
| X3 Consulting | Newcastle Upon Tyne | A rating |
| X3H LTD T/A GUNAYDIN | Kingston | A rating |
| X3M Marketing Ideas Limited | London | A rating |
| X4 Group Ltd | London | A rating |
| X7 SOLUTIONS LIMITED | Manchester | A rating |
| XA Cars Ltd | Slough | A rating |
| XAAR Technology Ltd | Cambridge | A rating |
| Xactly Limited | London | A rating |
| XAD TECHNOLOGIES LTD | Greenford | A rating |
| XAIRA UK LIMITED | Altrincham | A rating |
| Xalient Holdings Limited | Altrincham | A rating |
| Xama Technologies Limited | Camberley | A rating |
| Xampla Ltd | Cambridge | A rating |
| Xanadu Consultancy Limited | London | A rating |
| Xanda Ltd | London | A rating |
| Xantaro UK Ltd | London | A rating |
| Xanthe Quayle Landscape Architects | Huddersfield | A rating |
| Xap Therapeutics Limited | Babraham | A rating |
| Xappee Ltd | Birmingham | A rating |
| XAPPIE LIMITED | Salford | A rating |
| Xara Computers (UK) Limited t/a XC360 | London | A rating |
| Xara Group Ltd | Hemel Hempstead | A rating |
| Xavier Catholic Education Trust | Chertsey | A rating |
| Xaviers Accountants Ltd | Preston | A rating |
| Xavpuech Ltd. T/A No.1 Fleet Street | Castle Douglas | A rating |
| Xavvy Limited | Darlington | A rating |
| Xaz Click Solutions Ltd T/A Papa Johns | Waltham Cross | A rating |
| XBP EUROPE LIMITED | Egham | A rating |
| Xbridge Limited T/A Simply Business | London | A rating |
| Xburo UK Limited | Glasgow | A rating |
| XCALIBER CUT LTD | London | A rating |
| XCap Ecosystem Ltd | London | A rating |
| XCD HR | Basingstoke | A rating |
| XCECO LIMITED | Grimsby | A rating |
| Xceedance Limited | London | A rating |
| XCEL BESPOKE LIMITED | Stanmore | A rating |
| Xcel Homes Ltd | Market Harborough | A rating |
| Xcel Kitchens Uk Ltd | BRADFORD | A rating |
| XCEL LOGISTICS LIMITED | BASILDON | A rating |
| Xcel Motorsport Group Ltd | Wokingham | A rating |
| XCEL RESOURCES LIMITED | Ilford | A rating |
| Xcelentra Financial Services Ltd | Milton Keynes | A rating |
| XCELERATOR DENTAL LIMITED | St. Albans | A rating |
| XCELL HEALTHCARE SOLUTIONS LTD | Bolton | A rating |
| XCELLENCE CAR HIRE LTD | London | A rating |
| XCELLENT MANAGEMENT LTD | Ipswich | A rating |
| Xcelyst Limited | London | A rating |
| Xcentrik Solutions LTD | CROYDON | A rating |
| Xceptor Ltd | London | A rating |
| XCHANGER SERVICES LIMITED | Nuneaton | A rating |
| XCLUSIVE MOTOR SERVICES LTD | Birmingham | A rating |
| XCLUSIVEBLINKS BEAUTY | CANNING TOWN | A rating |
| XCMG UK SALES AND SERVICES LIMITED | High Wycombe | A rating |
| XCO2 Energy | London | A rating |
| XCom Associates Ltd | Norwich | A rating |
| XCZ Development Ltd | Liverpool | A rating |
| XD ACUPUNCTURE & MASSAGE LTD | London | A rating |
| XD INNOVATION LIMITED | Coventry | A rating |
| XD TAXIS LIMITED | Northampton | A rating |
| XDEFI Technologies Ltd (trading as XDEFI Wallet) | London | A rating |
| XDIRECTN | London | A rating |
| XDS Oxford Limited | Oxford | A rating |
| XDS Solutions Ltd | Chelmsford | A rating |
| Xeal Pharma Limited | Birmingham | A rating |
| Xebia UK Limited | London | A rating |
| XEBRAA TECH LTD | Luton | A rating |
| XEIAD | Ilkeston | A rating |
| Xeinadin Group Limited | London | A rating |
| Xelect Limited | St Andrews | A rating |
| Xelent Agency Limited | London | A rating |
| Xelion Limited | Derby | A rating |
| Xen News | Lither land | A rating |
| Xendl Software Limited | Bushey | A rating |
| Xenelsoft Technologies Limited | Bristol | A rating |
| Xenergie Limited | Chelmsford | A rating |
| Xeneta Ltd | London | A rating |
| XENEX HOLDING LTD | NEWCASTLE UPON TYNE | A rating |
| Xenial Intelligence Limited | Norwich | A rating |
| XENIUM INTERNATIONAL LIMITED | Surrey | A rating |
| Xenom Limited T/A Das Store/Bargain Booze/Costcutter | Folkestone | A rating |
| Xenon Hotels Limited T/a Park Avenue Blackpool Pier Hotel | Blackpool, | A rating |
| Xenon Lights Ltd | Bradford | A rating |
| Xenon Services Ltd | London | A rating |
| Xenophon's Horse Limited | Virginia Water | A rating |
| XENUK RESTAURANT LTD | Wokingham | A rating |
| XEO HOME LIMITED | Manchester | A rating |
| XEOTECH LIMITED | Stanmore | A rating |
| XEPOS LTD | Solihull | A rating |
| XeptionFlow Ltd | London | A rating |
| Xergy Group Limited | Aberdeen | A rating |
| XERIMIS LTD | Theale | A rating |
| Xero (UK) Limited | Milton Keynes | A rating |
| XEROTECH LTD | London | A rating |
| Xerox Limited | Uxbridge | A rating |
| XETROCUBE LTD | London | A rating |
| Xeven Solutions Limited | Greater London | A rating |
| Xflow Ltd | London | A rating |
| XFREEZ REFRIGERATION LTD | Birmingham | A rating |
| XGO Logistics Ltd | Orpington | A rating |
| xGround Holdings Ltd | Guildford | A rating |
| XHAXHO W4 LTD | London | A rating |
| XHIBIT (LONDON) LIMITED | London | A rating |
| XHYRE LTD | London | A rating |
| XI JING CATERING LTD | Windermere | A rating |
| XIAN NOODLE LIMITED | London | A rating |
| XIANYI LIMITED | London | A rating |
| Xiaomi Technology UK Limited | London | A rating |
| XIAOPANG EXPRESS LIMITED | GLASGOW | A rating |
| Xiaowangzi Media Ltd | Hull | A rating |
| Xiatech Ltd | London | A rating |
| XiCare Limited | Leigh-On-Sea | A rating |
| Xilinx XDC | Edinburgh | A rating |
| Xim Limited | Southampton | A rating |
| XIN DANCE LTD | Birmingham | A rating |
| Xinde Jiabai UK Co., Ltd. | London | A rating |
| Xindi Food Ltd Trading as Chopsticks Oriental | Sutton | A rating |
| XINET IT CONSULTING LIMITED | SLOUGH | A rating |
| XING HEALTH CARE LIMITED | London | A rating |
| Xinlung Group Limited | Manchester | A rating |
| XINTIANLUN UK LTD | London | A rating |
| XIONGQI LTD | Birmingham | A rating |
| XIONGQI SOUTHAMPTON LTD | Birmingham | A rating |
| Xiros Ltd | Leeds | A rating |
| XiTENYS Limited | Surrey | A rating |
| XITRICON LTD | Trowbridge | A rating |
| XIX Management Limited | London | A rating |
| XK studio Ltd | London | A rating |
| XL Accounting Solutions Limited | Edgware | A rating |
| XL Care Services Ltd | Leeds | A rating |
| XL CATLIN SERVICES SE T/A 'AXA XL' | LONDON | A rating |
| XL Displays Ltd | Peterborough | A rating |
| XL Electrical Excellence LTD | Poole | A rating |
| XL2023 TRADING LTD T/A GREAT WALL CHINESE RESTAURANT | Salisbury | A rating |
| XLCC Ltd | Billericay | A rating |
| XLINKS LIMITED | Billericay | A rating |
| Xlio Ventures Limited | London | A rating |
| XLMedia Plc | London | A rating |
| XLN ACCOUNTANTS LTD | London | A rating |
| XLN TAKEAWAY LTD | Milton Keynes, | A rating |
| XLNC CAR HIRE LTD | Birmingham | A rating |
| XLNTECH LTD | Reading | A rating |
| XLRT LTD | Manchester | A rating |
| XM DYNAMICS LTD | Oxford | A rating |
| XM2 UK Limited | London | A rating |
| XMHRA CONSULTANTS LTD | Slough | A rating |
| XML Ltd | London | A rating |
| XMOS Limited | Bristol | A rating |
| Xn Global Systems Ltd | Salford | A rating |
| Xn8 Ltd | Tipton | A rating |
| XOCEAN UK Ltd | Banbury | A rating |
| Xodus Group Limited | ABERDEEN | A rating |
| XOKO LTD | INVERNESS | A rating |
| Xolun Limited | Wolverhampton | A rating |
| Xometry UK Ltd | Chelmsford | A rating |
| XON FUELS UK LIMITED | Cornwall | A rating |
| Xoptix Limited | Malvern | A rating |
| Xoriant UK Limited | North Harrow | A rating |
| Xorlogics Ltd | London | A rating |
| Xorlogics Ltd. | London | A rating |
| Xown Solutions Limited | Oldbury | A rating |
| XP Factory plc | London | A rating |
| XP PLC | Pangbourne | A rating |
| XP Tavern | London | A rating |
| Xpansiv Operations Limited | London | A rating |
| xpate Ltd | London | A rating |
| Xpedent UK Ltd | West Chiltington | A rating |
| Xpergia Limited | Oxford | A rating |
| Xperia Motors Ltd T/A Lucky Seven Motors | Ilford | A rating |
| Xperiensys Limited | Richmond | A rating |
| Xpert Accountants Ltd | Manchester | A rating |
| Xpert Energy Installations Ltd | Aldermaston | A rating |
| Xpert IT & Security Ltd T/A Platinum Info Techs | London | A rating |
| Xpert Smile Ltd | Saltcoats, North Ayrshire | A rating |
| Xpert Solutionz Ltd | Manchester | A rating |
| XPERT TEC LTD | LONDON | A rating |
| Xpertnest Ltd | Biggleswade | A rating |
| XPERTSOL LIMITED | Reading | A rating |