| UK Readymix Concrete Bucks Ltd | Construction | 2025 |
| UK Residence Management Ltd | Real estate | 2025 |
| UK Roofing & Builders Limited | Construction | 2024 |
| UK Roofing & Gutters Ltd | Construction | 2025 |
| UK Skip Hire Ltd | Administrative & support | 2024 |
| UK Staff Relocations Ltd | Hospitality | 2024 |
| UK Stock Distribution Ltd | Wholesale & retail | 2022 |
| UK Tax Advisors Ltd | Professional & scientific | 2025 |
| UK Tills Ltd | Other services | 2019 |
| UK Tipper Hire Ltd | Water & waste | 2015 |
| UK Toilet Hire Limited | Water & waste | 2024 |
| UK Transfer Ltd | Transport & logistics | 2020 |
| UK Windows Ltd | Manufacturing | 2025 |
| Uk-Euro Estates Limited | Real estate | 2003 |
| UK247DEALS Ltd | Wholesale & retail | 2014 |
| UK26HED Ltd | Real estate | 2026 |
| Ukampala Ltd | Wholesale & retail | 2019 |
| Ukatech Company Ltd | Manufacturing | 2025 |
| Ukbuilding Blocks Limited | Construction | 2019 |
| UKD Techno Ltd | Professional & scientific | 2019 |
| Ukexpo Holdings Ltd | Wholesale & retail | 2022 |
| Ukgoods.Shop Ltd | Wholesale & retail | 2024 |
| Ukhano Ltd | Wholesale & retail | 2023 |
| Uk’S Pizza Ltd | Hospitality | 2023 |
| Ul-Nisa Global Ltd | Professional & scientific | 2024 |
| Ulez Compliant Cars Ltd | Wholesale & retail | 2023 |
| Ultima Cleaning Ltd | Administrative & support | 2000 |
| Ultimate Design & Build Construction Limited | Construction | 2022 |
| Ultimate Group Ltd | Wholesale & retail | 2026 |
| Ultimate Management Solutions Limited | Administrative & support | 2017 |
| Ultimate Power Yoga Ltd | Arts & recreation | 2025 |
| Ultra Protection Services Ltd | Administrative & support | 2022 |
| Ultra Tech Solutions UK Ltd | Construction | 2015 |
| Ultra Tread Ltd | Wholesale & retail | 2026 |
| Ultra Water Solutions Ltd | Professional & scientific | 2026 |
| Ultraquick Hire Limited | Manufacturing | 2014 |
| Ultrivexa Ltd | Wholesale & retail | 2026 |
| UM Crafts Ltd | Wholesale & retail | 2014 |
| Umagopal Limited | Real estate | 2022 |
| Umaima Courier Services Ltd | Transport & logistics | 2025 |
| Umar Hassan Maken.Co.Uk Limited | Other services | 2024 |
| Umar’S Cars Ltd | Wholesale & retail | 2025 |
| Umbrella 4U Ltd | Administrative & support | 2020 |
| Umbrella Contracts (UK) Ltd | Professional & scientific | 2014 |
| UMF Logistics Ltd | Transport & logistics | 2019 |
| Ummah Ltd | Wholesale & retail | 2025 |
| Ummati Ltd | Information & communication | 2016 |
| Ummati Residence Ltd | Real estate | 2024 |
| Umrah Heaven Limited | Administrative & support | 2025 |
| UMS Mart Ltd | Wholesale & retail | 2025 |
| Umut Cleaning Limited | Administrative & support | 2022 |
| UN3ENZO Consortium Ltd | Wholesale & retail | 2025 |
| Unatrac Group Services Limited | Administrative & support | 2021 |
| Unatrac Limited | Other services | 1997 |
| Underground Water Ltd | Water & waste | 2018 |
| Understanding Expertise Limited | Professional & scientific | 2010 |
| Undiscovered Workplace Limited | Transport & logistics | 2020 |
| Undisputed Boxing Promotions Ltd | Arts & recreation | 2025 |
| Uneque Convenients Limited | Wholesale & retail | 2021 |
| UNI Takeouts Ltd | Hospitality | 2025 |
| Uniayle Limited | Wholesale & retail | 2023 |
| Unibe Limited | Construction | 2023 |
| Unico Private Ltd | Other services | 2023 |
| Unicorn and Dinosaur Limited | Wholesale & retail | 2023 |
| Unifreight Global Logistics Limited | Transport & logistics | 2024 |
| Unifreight Global Ltd | Transport & logistics | 2025 |
| Unimacc Global Limited | Wholesale & retail | 2025 |
| Union Consulting Ltd | Professional & scientific | 2014 |
| UNION2 Properties Ltd | Real estate | 2020 |
| Uniq Healthcare Limited | Health & social care | 2019 |
| Uniqo Homes Ltd | Real estate | 2020 |
| Unique African Ltd | Health & social care | 2018 |
| Unique Bedroom and Kitchen Ltd | Construction | 2014 |
| Unique Bizz Ltd | Professional & scientific | 2023 |
| Unique Fast Food Ltd | Hospitality | 1997 |
| Unique Glazing Upvc and Aluminium Ltd | Manufacturing | 2025 |
| Unique IT Consultancy Ltd | Construction | 2010 |
| Unique Lifestyle Changes Enterprises Limited | Other services | 2008 |
| Unique Properties Southeast Ltd | Real estate | 2022 |
| Unique Stone Surface Berkshire Ltd | Manufacturing | 2022 |
| Unique Store Limited | Water & waste | 2025 |
| Unique United Limited | Wholesale & retail | 2019 |
| Uniqueness Cars Ltd | Transport & logistics | 2025 |
| Unison Direct Enterprise Ltd | Professional & scientific | 2025 |
| Unison Globus Alliances Limited | Professional & scientific | 2025 |
| Unitac UK Ltd | Wholesale & retail | 2018 |
| United Avia (Logistics) Ltd | Administrative & support | 2011 |
| United Business Express Limited | Real estate | 2013 |
| United Core Group Ltd | Financial services | 2025 |
| United Cyber Solutions Limited | Information & communication | 2021 |
| United Infosystems Limited | Information & communication | 2013 |
| United Kenning Rental Group Limited | Administrative & support | 1994 |
| United Kingdom Homeopathic Association Limited | Other services | 2023 |
| United Muscle Nutrition Ltd | Wholesale & retail | 2025 |
| United Retained Ltd | Administrative & support | 2023 |
| United Software Ltd | Information & communication | 2017 |
| United Windows & Conservatories Ltd | Manufacturing | 2012 |
| United Windows Ltd | Manufacturing | 2025 |
| Unitex Networks Limited | Construction | 2009 |
| Unitrax Consulting Limited | Information & communication | 2021 |