| UK Home Shop Ltd | Other services | 2017 |
| UK Home Textiles Ltd | Wholesale & retail | 2023 |
| UK Immigration Counsel Ltd | Professional & scientific | 2025 |
| UK International Group of Companies Ltd | Professional & scientific | 2001 |
| UK Land and Property LLP | | 2012 |
| UK Land Authority Ltd | Real estate | 2022 |
| UK Legal Services Limited | Professional & scientific | 1999 |
| UK MK Fast Food Limited | Hospitality | 2023 |
| UK Mobile & Vape Ltd | Wholesale & retail | 2025 |
| UK National Eco Ltd | Construction | 2023 |
| UK Nobel Services Ltd | Wholesale & retail | 2024 |
| UK Nuclear Waste Management Limited | Water & waste | 2007 |
| UK Ophthalmic Resourcing Ltd | Health & social care | 2016 |
| UK Organist Ltd | Arts & recreation | 2026 |
| UK Originals Ltd | Wholesale & retail | 2026 |
| UK Peptide Labs Ltd | Wholesale & retail | 2025 |
| UK Pet Taxi Ltd | Transport & logistics | 2025 |
| UK Plywood Ltd | Wholesale & retail | 2025 |
| UK Property Solutions (UPS) Ltd | Construction | 2021 |
| UK Rigging Holdings Ltd | Financial services | 2023 |
| UK Rigging Ltd | Other services | 1991 |
| UK Risers Limited | Extraterritorial | 2014 |
| UK Scots Ltd | Wholesale & retail | 2019 |
| UK Security Solutions Ltd | Administrative & support | 2019 |
| UK Sportives Ltd | Arts & recreation | 2022 |
| UK Spring Cleaners Limited | Other services | 2017 |
| UK Stargold Co Limited | Other services | 2025 |
| UK Subspot Fresh Ltd | Hospitality | 2014 |
| UK Supreme Tyres Bolton Ltd | Wholesale & retail | 2025 |
| UK Train Driver Academy Ltd | Transport & logistics | 2021 |
| UK Travel Ltd | Extraterritorial | 2003 |
| UK Travel Wizard Ltd | Administrative & support | 2025 |
| UK Utility Savers Limited | Other services | 2020 |
| UK Vape Club Limited | Extraterritorial | 2014 |
| UK Z-A Construction Limited | Construction | 2025 |
| Ukais International CIC | Education | 2022 |
| Ukera Limited | Wholesale & retail | 2025 |
| Ukey Limited | Professional & scientific | 2025 |
| Ukiyo Coffee Ltd | Hospitality | 2024 |
| Uklp (Trinity Point) Limited | Real estate | 2023 |
| Uklp Estates (Burscough 2) Limited | Real estate | 2016 |
| Uklp Estates (Burscough) Limited | Real estate | 2013 |
| Uklp Estates Limited | Real estate | 2013 |
| Uklp Gargrave Limited | Real estate | 2020 |
| Uklp London Road (Holdings) Limited | Administrative & support | 2021 |
| Uklp London Road Limited | Real estate | 2018 |
| Uklp Partners Limited | Real estate | 2013 |
| Uklp Project 25 Limited | Construction | 2025 |
| Uklp Ramsbury Limited | Real estate | 2020 |
| Ukmed Ltd | Information & communication | 2007 |
| Ukmotor Screen Limited | Extraterritorial | 2021 |
| UKR Interior Ltd | Construction | 2024 |
| Uksalespoint Ltd | Wholesale & retail | 2021 |
| Uksensent Ltd | Wholesale & retail | 2024 |
| Ukss Online Limited | Other services | 2023 |
| Uktech Installations Ltd | Construction | 2018 |
| Uktools Limited | Wholesale & retail | 2003 |
| Ulal Transport Limited | Transport & logistics | 2022 |
| Ulleswater Business Development Ltd | Administrative & support | 2018 |
| Ulleswater Properties Ltd | Real estate | 2018 |
| Ulti Pro UK Ltd | Manufacturing | 2026 |
| Ultimanet Ltd | Information & communication | 2023 |
| Ultimate Apartments. Ltd | Real estate | 2008 |
| Ultimate Business Service Ltd | Transport & logistics | 2020 |
| Ultimate Freedom Ltd | Wholesale & retail | 2023 |
| Ultimate Heating (NW) Ltd | Construction | 2002 |
| Ultimate Marketing (Global) Ltd | Professional & scientific | 2024 |
| Ultra Cleaning Service Limited | Administrative & support | 2012 |
| Ultra Doors NW Ltd | Manufacturing | 2021 |
| Ultra Peptides Ltd | Professional & scientific | 2026 |
| Ultrablast (UK) Ltd | Administrative & support | 2016 |
| Ultrabright Windows Ltd | Construction | 2019 |
| UM Everywhere Limited | Administrative & support | 2024 |
| Umar Community Educational Trust Limited | Health & social care | 2012 |
| Umar Ltd | Financial services | 2024 |
| Umar Quality Food Ltd | Wholesale & retail | 2018 |
| Umaraz EM Ltd | Hospitality | 2024 |
| Umarji Ltd | Financial services | 2025 |
| Umarji Optical Ltd | Health & social care | 2010 |
| Umayr Optix Ltd | Health & social care | 2023 |
| Umbrella Consultants Ltd | Administrative & support | 2020 |
| Umbrellaworld Limited | Wholesale & retail | 2001 |
| Umbuvak Limited | Information & communication | 2017 |
| Umerscho Property Limited | Real estate | 2025 |
| Ummim Ltd | Information & communication | 2026 |
| Umoja Housing Association Limited | Real estate | 2020 |
| Umraj UK Ltd | Wholesale & retail | 2022 |
| Unaa Ltd | Wholesale & retail | 2021 |
| Unbranded Global Ltd | Wholesale & retail | 2020 |
| Unbroken Gymwear Ltd | Wholesale & retail | 2023 |
| Uncab Limited | Administrative & support | 2009 |
| Uncivilised Media CIC | Information & communication | 2023 |
| Uncle George Transport Ltd | Transport & logistics | 2019 |
| Unclepee Limited | Real estate | 2023 |
| Uncrowd Limited | Professional & scientific | 2018 |
| Underdog Marketing Limited | Professional & scientific | 2021 |
| Underdog Protection 365 Ltd | Administrative & support | 2025 |
| Underley Educational Services | Education | 1997 |
| Underley Schools Limited | Education | 1999 |
| Underwell Ltd | Real estate | 2003 |