| UK Chicken Town Limited | Professional & scientific | 2018 |
| UK Compliance Contractor Limited | Administrative & support | 2023 |
| UK Dreamway Limited | Professional & scientific | 2019 |
| UK Endometriosis Centre Limited | Health & social care | 2026 |
| UK Immigration Law Advisers Ltd. | Professional & scientific | 2014 |
| UK Incoming Limited | Administrative & support | 1974 |
| UK Kolat Brick Company Limited | Administrative & support | 2019 |
| UK Laser IT Ltd | Other services | 2022 |
| UK Logs Ltd | Extraterritorial | 2025 |
| UK Medic Limited | Health & social care | 2021 |
| UK MG Holdings Ltd | Real estate | 2018 |
| UK Mortgages & Finance Ltd | Financial services | 2016 |
| UK Mortgages (Ukmortgages.Co.Uk) Ltd | Extraterritorial | 2018 |
| UK Premier Blinds Ltd | Wholesale & retail | 2016 |
| UK Prime Payroll Ltd | Professional & scientific | 2024 |
| UK Property Bridging Ltd | Financial services | 2025 |
| UK Property Investment Group Ltd | Households | 2016 |
| UK Shopping Discount Collection Ltd | Information & communication | 2013 |
| UK Valeting Services Limited | Other services | 2016 |
| UK Website Workshop Limited | Professional & scientific | 2008 |
| UK247 Ltd | Information & communication | 2016 |
| UK2M Limited | Wholesale & retail | 2016 |
| UKCARAVANS4HIRE.COM Limited | Professional & scientific | 2009 |
| Ukcy Consultants Ltd | Professional & scientific | 2019 |
| Ukdnet Ltd | Administrative & support | 2022 |
| Uksignwarehouse Limited | Administrative & support | 2012 |
| Ulcc Holdings Limited | Financial services | 2022 |
| Ullum Ltd | Wholesale & retail | 2023 |
| ULS Holdings Limited | Financial services | 2025 |
| Ultima Bidco Limited | Financial services | 2019 |
| Ultima Holdco Limited | Financial services | 2019 |
| Ultima Midco Limited | Financial services | 2019 |
| Ultima Nominee Limited | Professional & scientific | 2019 |
| Ultima Topco Limited | Professional & scientific | 2019 |
| Ultimage Limited | Information & communication | 2021 |
| Ultimate Builds Ltd | Construction | 2025 |
| Ultimate Law Ltd | Professional & scientific | 2008 |
| Ultra IP Limited | Professional & scientific | 2024 |
| Ultraframe Quest Trustee Limited | Professional & scientific | 1999 |
| Ultraguard Alarms Limited | Wholesale & retail | 1993 |
| UM Consulting Limited | Information & communication | 2025 |
| UM Trident Buyer Limited | Financial services | 2026 |
| Umar Nermine Investment Limited | Real estate | 2026 |
| Umar Nermine Limited | Health & social care | 2016 |
| Umbizo Limited | Professional & scientific | 2018 |
| Umbizo Software Solutions Ltd | Information & communication | 2025 |
| Umbranox Holdings Ltd | Financial services | 2026 |
| Ummkardous Limited | Health & social care | 2025 |
| Unal & Aveleira Consulting Limited | Professional & scientific | 2022 |
| Underfound Limited | Other services | 2025 |
| Understone Ltd | Information & communication | 2025 |
| Unhooked Communications Ltd | Professional & scientific | 2017 |
| Uni-Tel Business Communications Limited | Information & communication | 2011 |
| Uni-Tel Communications Group Limited | Information & communication | 2023 |
| Unialloys Limited | Wholesale & retail | 2023 |
| Unicon Holdings Limited | Professional & scientific | 1984 |
| Unicon Properties Limited | Real estate | 1974 |
| Unidex Limited | Administrative & support | 2006 |
| Unified Book Distribution Ltd. | Information & communication | 2025 |
| Unified Citizens Ltd | Education | 2020 |
| Uninvest Investment Solutions (UK) Limited | Professional & scientific | 2020 |
| Union Four Ltd | Construction | 2016 |
| Union Square Advisors UK Ltd | Financial services | 2025 |
| Uniondale Property Limited | Real estate | 2026 |
| Unique Homes and Developments Ltd | Construction | 2020 |
| Unique Production and Sales Limited | Wholesale & retail | 2025 |
| Unique Television Limited | Information & communication | 1991 |
| Unique Venues of Manchester Ltd | Information & communication | 2013 |
| United Ambulance C.I.C. | Transport & logistics | 2025 |
| United City Properties Limited | Real estate | 2019 |
| United Colours Hospitality Group Ltd | Hospitality | 2024 |
| United Kapital Limited | Financial services | 2008 |
| United Mining Services Construction Limited | Mining & quarrying | 2024 |
| United Mining Services Limited | Mining & quarrying | 2015 |
| United Mining Services Projects Limited | Professional & scientific | 2015 |
| United QP Consulting Ltd | Administrative & support | 2022 |
| United Services Co.(St.Helens)Limited | Other services | 1946 |
| United Surveyors Limited | Professional & scientific | 2000 |
| Unitedlyaa Ltd | Wholesale & retail | 2023 |
| Unity FX Limited | Other services | 2017 |
| Unity Through Yoga Ltd | Health & social care | 2023 |
| Universal Welfare Ltd | Health & social care | 2023 |
| Unruly Minds Ltd | Professional & scientific | 2022 |
| Unstoppable Creative Media Limited | Professional & scientific | 2022 |
| Untye AI Limited | Professional & scientific | 2026 |
| Unusual Customs Holding Limited | Transport & logistics | 2025 |
| Uppal Homes Ltd | Real estate | 2024 |
| Upstream Legal Advisors Limited | Professional & scientific | 2020 |
| Upstream Marketing Programs Limited | Administrative & support | 2012 |
| Upton Community Health Care Limited | Health & social care | 2002 |
| Upton Management Services LLP | | 2018 |
| Upton Medical Limited | Professional & scientific | 2005 |
| Upton Mount Management Company Ltd | Households | 2000 |
| Urban Domestics Limited | Other services | 2010 |
| Urban Global Property Solutions Ltd | Construction | 2025 |
| Urban Ventures Properties Ltd | Real estate | 2023 |
| Urbanedge Renovations Manchester Limited | Construction | 2026 |
| Urbanize Homes Limited | Real estate | 2012 |
| Urbanize Limited | Real estate | 2000 |
| Urbano Property Limited | Construction | 2021 |