| Udeliver & Co. Ao.I Ltd | Transport & logistics | 2025 |
| Ufixi Ltd | Information & communication | 2026 |
| Ugca Limited | Other services | 2023 |
| UGS Common Law Church Ltd | Professional & scientific | 2025 |
| UK EDU Ltd | Wholesale & retail | 2018 |
| UK Event Security Services Ltd | Administrative & support | 2024 |
| UK JAM Holdings Ltd | Wholesale & retail | 2026 |
| UK Padel Limited | Arts & recreation | 2020 |
| UK Pharma Peptides Ltd | Wholesale & retail | 2025 |
| UK Properties Online Limited | Information & communication | 2005 |
| UK Property Docs Ltd | Information & communication | 2025 |
| UK Rail Freight Ltd | Transport & logistics | 2025 |
| UK Roofing Crews Ltd | Construction | 2024 |
| UK Tight Ends Ltd | Administrative & support | 2023 |
| UK Yaay Limited | Hospitality | 2018 |
| Ukame Ltd | Administrative & support | 2025 |
| Ukeen Limited | Wholesale & retail | 2022 |
| Ukfriendbuy Ltd | Wholesale & retail | 2021 |
| Uktaxi Accountant Ltd | Transport & logistics | 2014 |
| Ukvn Connect Ltd | Wholesale & retail | 2022 |
| Ultimate Clientele Limited | Professional & scientific | 2015 |
| Ultimate Recovery Ltd | Health & social care | 2025 |
| Ultimated Ltd | Wholesale & retail | 2024 |
| Ultimia Limited | Administrative & support | 2022 |
| Ultra Trade Frames (Holdings) Limited | Wholesale & retail | 2008 |
| Ultra Trade Frames Limited | Wholesale & retail | 2001 |
| Ultrarad NDT Limited | Professional & scientific | 2006 |
| Ultrastream Business Services Limited | Information & communication | 2020 |
| Ultratiz Cloud Enterprise Ltd | Information & communication | 2025 |
| Umami Search Ltd | Administrative & support | 2022 |
| Umar and Co Group Ltd | Wholesale & retail | 2026 |
| UMUT2020 Ltd | Hospitality | 2020 |
| Unbound Innovations Ltd | Manufacturing | 2025 |
| UNBOUND6D Ltd | Information & communication | 2026 |
| Unbounded Systems Ltd | Information & communication | 2016 |
| Unboxd Ltd | Education | 2020 |
| Unbridled Studio Ltd | Extraterritorial | 2023 |
| Undercover Glamour Limited | Professional & scientific | 2009 |
| Underfloor Shop Limited | Construction | 2023 |
| Underwood Properties Ltd | Real estate | 2025 |
| Unearthed Rituals Ltd | Manufacturing | 2023 |
| Unfolding Entertainment Ltd | Information & communication | 2015 |
| Unhinged Gifts Retail (UK) Ltd | Wholesale & retail | 2023 |
| Unhinged Gifts UK (Marketplace) Ltd | Wholesale & retail | 2024 |
| UNI Merit Ltd | Education | 2022 |
| Unifi Group Ltd. | Information & communication | 2018 |
| Unified Partners Limited | Information & communication | 2024 |
| Uniglobe Business and Marketing Solutions Limited | Information & communication | 2025 |
| Unilug Ltd | Administrative & support | 2026 |
| Union Brew Coffee Limited | Hospitality | 2026 |
| Unipro Media Ltd | Professional & scientific | 2025 |
| Unique Global Talent Limited | Professional & scientific | 2026 |
| Unique Leisure Enterprises Ltd | Hospitality | 2018 |
| Unique UK Stays Group Limited | Hospitality | 2025 |
| Unique Zone Ltd | Wholesale & retail | 2025 |
| Uniqueabc Ltd | Wholesale & retail | 2021 |
| Unit 1 Gym Limited | Arts & recreation | 2013 |
| United Defence Limited | Wholesale & retail | 2025 |
| United Nations Space Private Limited | Professional & scientific | 2019 |
| United Tastes of America Ltd | Hospitality | 2014 |
| Unity Heart Ltd | Health & social care | 2024 |
| Unitysprout Ltd | Manufacturing | 2025 |
| Univantis Limited | Information & communication | 2022 |
| Universal Access Ltd | Construction | 2022 |
| Universal Brokers Limited | Wholesale & retail | 2019 |
| Universal Data Solutions Limited | Information & communication | 2025 |
| Universal Holiday Lets Ltd | Real estate | 2025 |
| Universal Networking Insights Training & Development Limited | Construction | 2025 |
| Universo Heating Ltd | Construction | 2024 |
| Unjn Ltd | Wholesale & retail | 2026 |
| Unknown Hub Ltd | Wholesale & retail | 2026 |
| Unlock Kenya Ltd | Administrative & support | 2025 |
| Unlox Ltd | Information & communication | 2022 |
| Unlu Group Ltd | Wholesale & retail | 2026 |
| Unmatched Tech Limited | Information & communication | 2024 |
| Unseen Wizards Limited | Information & communication | 2019 |
| Untitled Summit Ltd | Information & communication | 2026 |
| Unto Others Ltd | Other services | 2020 |
| Untold Labs Limited | Professional & scientific | 2026 |
| Unultraprocessed Limited | Manufacturing | 2025 |
| UP Level Arabia Ltd | Construction | 2026 |
| UP North Real Estate Ltd | Real estate | 2024 |
| UP Sticks Campers Limited | Administrative & support | 2020 |
| Up-To-Date Information Services Limited | Information & communication | 2018 |
| UPC Systems Ltd | Information & communication | 2022 |
| Upcheck Ltd | Information & communication | 2022 |
| Uper Digital Ltd | Information & communication | 2024 |
| Uplift People Consulting Ltd | Professional & scientific | 2025 |
| Upon a Hill Limited | Professional & scientific | 2023 |
| Upper Liney Farm Enterprises Ltd | Hospitality | 2013 |
| Upperton Farmhouse Ltd | Real estate | 2018 |
| Upscale Establishment Ltd | Construction | 2021 |
| Upsidelet Limited | Real estate | 2025 |
| Uptime Education Holdings Limited | Financial services | 2023 |
| Upventa Ltd | Information & communication | 2020 |
| Upvia Ltd | Information & communication | 2025 |
| URA Software Ltd | Information & communication | 2026 |
| Urban Apiarist 1 Limited | Agriculture & fishing | 2021 |
| Urban ARC Ltd | Wholesale & retail | 2013 |
| Urban FOX Clothing Limited | Wholesale & retail | 2024 |