| 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 |
| Xplora Technologies Limited | Chiswick | A rating |
| Xplore Clothing Limited | Leicester | A rating |
| XPLORO LIMITED | Manchester | A rating |
| Xplus London Limited | Kingston | A rating |
| XPO Global Ltd | Sutton | A rating |
| XPO Supply Chain UK Limited | Northampton | A rating |
| XPO Transport Solutions UK Limited | Northampton | A rating |
| XPRESS ALL LTD | Hillingdon | A rating |
| XPRESS HAULAGE LTD | NOTTINGHAM | A rating |
| Xpress Logistic Services Ltd | West Drayton | A rating |
| XPRESS MONEY GLOBAL LIMITED | Birmingham | A rating |
| XPRESS PARCEL LTD | London | A rating |
| XPRESS SOLUTION GLOBAL LIMITED T/A DIRECT FROM UK | West Bromwich | A rating |
| Xpress Tyres Ltd | Manchester | A rating |
| Xpress UK Wholesale Ltd | Colchester | A rating |
| Xpression MCR Limited | Nottingham | A rating |
| XPRESSS 24/7 LTD | Edinburgh | A rating |
| XPRT CONSTRUCTION LIMITED | Borehamwood | A rating |
| XPS CONSTRUCTION AND SKILLS LEARNING LIMITED | London | A rating |
| XPS Pensions Limited | Reading | A rating |
| XQUISITE PROPERTIES LIMITED | London | A rating |
| XR GLOBAL (UK) LIMITED | London | A rating |
| XR Therapeutics | Gateshead | A rating |
| XRAY GLAZING LIMITED | LONDON | A rating |
| XRC Robotics Ltd | Manor House Lane, Datchet | A rating |
| XRECYCLING LTD | Leicester | A rating |
| XRENEWABLE LTD | London | A rating |
| Xriba LTD | London | A rating |
| XRM Technologies | Uxbridge | A rating |
| XRN Engineering Ltd | Milford | A rating |
| XroadMedia Limited | London | A rating |
| XRP Health Ltd | London | A rating |
| XRP Traders ltd | Leicester | A rating |
| XRP VENTURES LTD T/A Armando's | Redcar | A rating |
| XS Global Europe Limited | London | A rating |
| XSITE ARCHITECTURE LLP | Newcastle upon Tyne | A rating |
| XSolutions365 Ltd | Edinburgh | A rating |
| XSQUARE UK LTD T/a Cherry Cosmetics | Leicester, | A rating |
| Xstrahl Limited | Walsall | A rating |
| XTB Limited | London | A rating |
| XTEC Limited | Manchester | A rating |
| XTECH SOLUTION PRIVATE LIMITED | Oldham | A rating |
| XTEL U.K. Limited | London | A rating |
| Xtend Global | Worthing | A rating |
| Xtensible Logix Ltd | Luton | A rating |
| Xtera Ltd | Romford | A rating |
| XTM International Ltd | Bude | A rating |
| XTOB SUPPORT SERVICES NW LTD | London | A rating |
| Xtra Building Supplies Ltd | Heston | A rating |
| XTRA CARE PROVIDERS LTD | RADSTOCK | A rating |
| XTRA CARE SERVICES LTD | Wood Green | A rating |
| Xtra Healthcare | Corby | A rating |
| Xtra Limited | London | A rating |
| Xtra Xtra Ltd | Lowestoft | A rating |
| Xtrac Ltd | Thatcham | A rating |
| Xtracare Ltd | Maidstone | A rating |
| Xtravirt Limited | Leatherhead | A rating |
| Xtreme Bimmerc Cars Ltd | Brentford | A rating |
| XTREME INTELLIGENCE LIMITED | Beaconsfield | A rating |
| Xtreme Pharmacy | Birmingham | A rating |
| XTREME SECURITY LTD | Coventry | A rating |
| XTREMETECHXPERTS LIMITED | Guisborough | A rating |
| Xtremity & Spinal Solutions Limited | Thornaby on Tees | A rating |
| XTX Research LLP | London | A rating |
| Xu Li Limited | London | A rating |
| XUM Enterprise Ltd | Manchester | A rating |
| xUnlocked Limited | London | A rating |
| XUREL LIMITED | Folkestone | A rating |
| Xurrent Software UK Ltd | London | A rating |
| xWatts Limited | Cambridge | A rating |
| XWORKS TRAINING LIMITED T/A Smileworks Aesthetic Training HUB | Liverpool | A rating |
| XX Bio UK Limited | Cambridge | A rating |
| XXCELL LIMITED | London | A rating |
| XXYD Ltd | Reigate Surrey | A rating |
| XY Automation Ltd | Wales | A rating |
| XY Capital Europe Limited | London | A rating |
| XY Sense UK Limited | Cheshire | A rating |
| XYB Limited | London | A rating |
| XYFIL LTD | Preston | A rating |
| Xylem Water Services Ltd | Nottingham | A rating |
| Xyme Limited | Oxford | A rating |
| Xynera Technologies Limited | GLOUCESTER | A rating |
| XYNEXCARE LIMITED | Bolton | A rating |
| Xynotech Ltd | Sutton | A rating |
| Xynteo Ltd | London | A rating |
| XYO WHOLESALE LTD | Birmingham | A rating |
| XYRESIC LIMITED T/A STONE PHARMACY | STONE | A rating |
| XYZ Reality Ltd | London | A rating |
| XZONE MEDIA LTD | Hull | A rating |
| XZONETRADING LIMITED | London | A rating |
| XZYAB Ltd | Oxford | A rating |