| U a Engineering Limited | Wholesale & retail | 1964 |
| U and I Holdings Limited | Real estate | 2025 |
| U Thai Therapy Massage Limited | Other services | 2021 |
| U&A Advisory Services Ltd | Professional & scientific | 2019 |
| UA Commerce Ltd | Wholesale & retail | 2026 |
| Uber Bike Components Ltd | Wholesale & retail | 2010 |
| Uber Haus Ltd | Construction | 2014 |
| Uberlink Ltd | Wholesale & retail | 2018 |
| Ubuntu Initiative CIC | Education | 2025 |
| UC Developments Limited | Real estate | 2003 |
| Udirect Ltd | Information & communication | 2020 |
| UFC1 Consulting Ltd | Administrative & support | 2025 |
| Uflit Gold Ltd | Real estate | 2024 |
| Uflit Investments Ltd | Real estate | 2022 |
| Uflit Lettings Ltd | Real estate | 2022 |
| Uflit Ltd | Real estate | 2019 |
| Uflit Property Sourcing Ltd | Real estate | 2022 |
| Ujify Mart Ltd | Wholesale & retail | 2025 |
| UJU Group Limited | Information & communication | 2026 |
| UK & Bradford Shari'Ah Chambers Office Ltd | Professional & scientific | 2019 |
| UK Cleaning Network Limited | Administrative & support | 2019 |
| UK Dera Ltd | Hospitality | 2025 |
| UK Drywall and Ceilings Limited | Construction | 2014 |
| UK Financial Solutions Limited | Financial services | 2019 |
| UK Garage Equipment (Sales) Ltd | Manufacturing | 2008 |
| UK Healthcare Professionals Ltd | Health & social care | 2022 |
| UK Housing Club CIC | Real estate | 2024 |
| UK Kitchen Makeovers Limited | Manufacturing | 2013 |
| UK Labs Limited | Professional & scientific | 2021 |
| UK Mental Health Transport Ltd | Transport & logistics | 2018 |
| UK Mortgage Advice Ltd | Financial services | 2013 |
| UK Nationwide Cleaning Services Limited | Administrative & support | 2011 |
| UK Ndjangui Club Ltd | Other services | 2023 |
| UK Property Specialists Ltd | Wholesale & retail | 2018 |
| UK Racking Repairs Limited | Manufacturing | 2025 |
| UK Rooflights Online Limited | Financial services | 2024 |
| UK Siphonic Systems Ltd | Construction | 2026 |
| UK Smart Interiors Ltd | Construction | 2019 |
| UK Sofa Ltd | Manufacturing | 2024 |
| UK Tax Academy Ltd | Education | 2025 |
| UK Tax Consultancy Ltd | Professional & scientific | 2026 |
| UK Tax Digital Services Ltd | Professional & scientific | 2026 |
| UK Value Hub Ltd | Wholesale & retail | 2026 |
| UK Van Parts Ltd | Wholesale & retail | 2020 |
| UK Vans Direct Limited | Wholesale & retail | 2010 |
| UK Watch Empire Limited | Wholesale & retail | 2016 |
| Uk-Minimarket S60 Limited | Wholesale & retail | 2025 |
| Ukas Properties Ltd | Real estate | 2012 |
| Ukblanks Ltd | Wholesale & retail | 2021 |
| Ukrainian Roma Initiative Centre in Yorkshire C.I.C. | Education | 2026 |
| Ultimate Accident Repair Limited | Wholesale & retail | 2012 |
| Ultimate Carp Giveaways Ltd | Wholesale & retail | 2021 |
| Ultimate Garden Buildings Limited | Construction | 2020 |
| Ultra GRP Limited | Professional & scientific | 2007 |
| Ultra Phone Accessories Ltd | Wholesale & retail | 2023 |
| Ultrapower Ltd | Other services | 2023 |
| Um's Bazaar Ltd | Wholesale & retail | 2025 |
| Umer Daraz Tarding Ltd | Wholesale & retail | 2025 |
| UMH Ltd | Health & social care | 2017 |
| UMT Holdings Ltd | Professional & scientific | 1996 |
| Under the Hood Garage Limited | Wholesale & retail | 2024 |
| Undercause Limited | Real estate | 1996 |
| Underhook Ltd | Administrative & support | 2016 |
| Underthehammer Ltd | Wholesale & retail | 2013 |
| Underwood Meat (Holdings) Limited | Professional & scientific | 2002 |
| Underwood Meat (Topco) Limited | Wholesale & retail | 2022 |
| Underwood Meat Company Limited | Wholesale & retail | 1992 |
| Unicarz Ltd | Wholesale & retail | 2021 |
| Unicorn Contracts Hire Ltd | Transport & logistics | 2018 |
| Unicorn Private Hire Ltd | Transport & logistics | 2018 |
| Unigraph (UK) Limited | Wholesale & retail | 1980 |
| Uniinvester Ltd | Real estate | 2025 |
| Union Logistics Ltd | Transport & logistics | 2018 |
| Union Street Garage (Rotherham) Ltd | Wholesale & retail | 2015 |
| Union Track Limited | Construction | 2006 |
| Unique Chic Boutique Limited | Wholesale & retail | 2022 |
| Unique Forms Limited | Manufacturing | 2001 |
| Unique Intelligent Security Ltd | Administrative & support | 2022 |
| Unique Resolutions Ltd | Construction | 2018 |
| Unique School Solutions Ltd | Administrative & support | 2017 |
| Unique Solutions Inc. Ltd | Other services | 2025 |
| Uniquely ME Ltd | Real estate | 2017 |
| Unit Cladding Ltd | Construction | 2025 |
| Unite Fundraising Limited | Other services | 2019 |
| United African Food Limited | Wholesale & retail | 2012 |
| United Carpets (Commercial) Limited | Wholesale & retail | 2012 |
| United Carpets (Franchisor) Limited | Wholesale & retail | 2004 |
| United Carpets (Property) Limited | Real estate | 2012 |
| United Carpets Group Limited | Administrative & support | 2004 |
| United Carpets Holdings Limited | Real estate | 1992 |
| United Detailing Limited | Administrative & support | 2026 |
| United Elevators Limited | Wholesale & retail | 2013 |
| United Market Noor Ltd | Wholesale & retail | 2026 |
| Unity Aquatics Ltd | Wholesale & retail | 2025 |
| Unity Boxing Centre CIC | Arts & recreation | 2022 |
| Unity Centre Rotherham | Administrative & support | 2001 |
| Unity Cleaning Group Ltd | Administrative & support | 2025 |
| Unity Gifts (Yorkshire) Ltd | Manufacturing | 2021 |
| Unity Life Care and Services Ltd | Health & social care | 2026 |
| Universal Barrier Solutions Limited | Wholesale & retail | 2017 |