| UA Foods Limited | Hospitality | 2026 |
| UBA Security Systems Ltd | Other services | 2022 |
| Ubah Media LAB Ltd | Information & communication | 2025 |
| Ubiquitous Global Services Ltd | Construction | 2019 |
| Ubuntu Health Limited | Health & social care | 2024 |
| Ucar Investment Ltd | Wholesale & retail | 2016 |
| Ucar London Ltd | Wholesale & retail | 2018 |
| Ucar Properties Limited | Real estate | 1993 |
| Ucce Ltd | Construction | 2024 |
| UCR Decor Ltd | Construction | 2025 |
| UDC Trans Ltd | Transport & logistics | 2021 |
| UFS Engineering Ltd | Construction | 2014 |
| UK 3D Tiles Limited | Construction | 2018 |
| UK Basak Kuafor Ltd | Other services | 2021 |
| UK Black and White Limited | Wholesale & retail | 2018 |
| UK Buying House Ltd | Wholesale & retail | 2025 |
| UK Central Builders & Roofing Limited | Construction | 2019 |
| UK Defibs.Co.Uk Ltd | Wholesale & retail | 2021 |
| UK Events and Hospitality Limited | Wholesale & retail | 2022 |
| UK Fast Ltd | Wholesale & retail | 2023 |
| UK FCR Ltd | Hospitality | 2018 |
| UK Financial Accountants Ltd | Professional & scientific | 2023 |
| UK Fruit & VEG Ltd | Wholesale & retail | 2022 |
| UK Garage of Enfield Limited | Wholesale & retail | 2018 |
| UK Garages Ltd | Wholesale & retail | 2022 |
| UK Gezi Ltd | Administrative & support | 2026 |
| UK Haider Limited | Wholesale & retail | 2018 |
| UK Home Solutions Limited | Wholesale & retail | 2016 |
| UK ICR Ltd | Hospitality | 2024 |
| UK Nails Hersham Limited | Other services | 2023 |
| UK Personal Trainer Limited | Health & social care | 2018 |
| UK Rami News Limited | Wholesale & retail | 2021 |
| UK Sahra Ltd | Wholesale & retail | 2017 |
| UK Snacks Limited | Manufacturing | 2003 |
| UK Tuition Centre Ltd | Education | 2025 |
| UK Weather Shield Limited | Construction | 2013 |
| UK- BD Food Safety Consultants Ltd | Professional & scientific | 2021 |
| Uk.Emeg Ltd | Construction | 2022 |
| UKA Capital Ltd | Construction | 2024 |
| Ukcityfacades Limited | Construction | 2020 |
| Ukcooling Limited | Construction | 2019 |
| Ulas Structure and Development Ltd | Real estate | 2024 |
| Ulaz Ltd | Information & communication | 2023 |
| ULB Technic Ltd | Wholesale & retail | 2020 |
| Ultavor Limited | Information & communication | 2025 |
| Ulti-Fibre Ltd | Administrative & support | 2026 |
| Ultima BIM Limited | Professional & scientific | 2021 |
| Ultimate Roofing Solutions Ltd | Construction | 2024 |
| Ultimategoconstruction Limited | Real estate | 2014 |
| Ultracolour Limited | Manufacturing | 1975 |
| Ultramodified Limited | Financial services | 2025 |
| UM Haringey Ltd | Wholesale & retail | 2026 |
| UM Property Group Ltd | Hospitality | 2018 |
| Umami Concepts Ltd | Hospitality | 2024 |
| Umha Food Limited | Hospitality | 2019 |
| UMT Global Limited | Transport & logistics | 2022 |
| UMT Travels and Exchange Ltd | Other services | 2010 |
| Umut CEM Ltd | Hospitality | 2024 |
| Umut Investments Ltd | Real estate | 2026 |
| Umut Windows Ltd | Construction | 2018 |
| Unbound Media Ltd | Professional & scientific | 2023 |
| Unclebenentertainment Limited | Real estate | 2020 |
| Underwoods Electrical Distributors Limited | Wholesale & retail | 1955 |
| Underwoods Group Limited | Professional & scientific | 1988 |
| Unext Ltd | Real estate | 2022 |
| Unibiz Care Limited | Health & social care | 2014 |
| Unicorn Cloud Limited | Real estate | 2025 |
| Unicorn Connected Apps Limited | Information & communication | 2022 |
| Unionited Limited | Health & social care | 2023 |
| Uniq EJ Solutions Limited | Wholesale & retail | 2018 |
| Uniq Trading and Consulting Limited | Wholesale & retail | 2020 |
| Uniqone Limited | Information & communication | 2021 |
| Unique Angels Care Limited | Health & social care | 2025 |
| Unique Bride Ltd | Wholesale & retail | 2020 |
| Unique Brothers Ltd | Real estate | 2019 |
| Unique DIY & Handyman Limited | Construction | 2020 |
| Unique Healthcare Services Limited | Health & social care | 2018 |
| Unique UK Services Limited | Construction | 2016 |
| Unique Way Property and Development Ltd | Real estate | 2022 |
| Unispec Chemicals Limited | Manufacturing | 2008 |
| Unite in Fitness Ltd | Arts & recreation | 2021 |
| Unitec Trading Ltd | Professional & scientific | 2018 |
| United AID & Logistics | Health & social care | 2022 |
| United Aims Foundation CIC | Health & social care | 2024 |
| United Continental Traders Ltd | Wholesale & retail | 2022 |
| United Roofing Contractors Ltd | Construction | 2026 |
| United Transport Holdings Limited | Financial services | 2023 |
| Unity Developments Limited | Real estate | 2001 |
| Unity Funeral Care Ltd | Other services | 2021 |
| Unity Property Investments Enfield Ltd | Real estate | 2025 |
| Universal Consult Ltd | Information & communication | 2013 |
| Universal Imports Limited | Wholesale & retail | 1991 |
| Universal Maintenance Services Ltd | Other services | 2018 |
| Universal Motion Trade Limited | Extraterritorial | 2013 |
| Universal Pipework Limited | Construction | 2011 |
| University Design Forum | Education | 2015 |
| Uniworld UK Group Ltd | Information & communication | 2011 |
| Unkn Ltd | Information & communication | 2023 |
| Upheaval Limited | Health & social care | 2013 |
| Upper Cuts Barbers Ltd | Other services | 2022 |