| United Auto Care Limited | Wholesale & retail | 2022 |
| United Building Services Ltd | Construction | 2024 |
| United Caps Dinnington Limited | Manufacturing | 2018 |
| United Car Sales Ltd | Wholesale & retail | 2025 |
| United Cleaning & Hospitality Services Ltd | Administrative & support | 2025 |
| United Contract Cleaning Ltd | Administrative & support | 2020 |
| United Convenience Limited | Wholesale & retail | 2025 |
| United Crane Holdings (2018) Ltd | Manufacturing | 2018 |
| United Crane Services Limited | Manufacturing | 1986 |
| United Developments Ltd | Real estate | 2025 |
| United Engineering (Chesterfield) Ltd | Manufacturing | 2005 |
| United Fire Safety Ltd | Administrative & support | 2021 |
| United Fried Chicken Maltby Limited | Hospitality | 2014 |
| United Homes.Co.Uk (Rentals) Ltd | Real estate | 2014 |
| United Industries Operations Limited | Extraterritorial | 1929 |
| United Installs Ltd | Construction | 2025 |
| United Jointing and Electrical Services Ltd | Construction | 2026 |
| United Motorcycle Group Ltd | Wholesale & retail | 2026 |
| United Northern Distribution Limited | Real estate | 2020 |
| United Real Estate Marketing UK Ltd | Real estate | 2019 |
| United Roofing Products Limited | Extraterritorial | 2007 |
| United Vape Ltd | Wholesale & retail | 2025 |
| United WE Climb CIC | Education | 2021 |
| Uniti Power Ltd | Wholesale & retail | 2021 |
| Unity Centre Limited(The) | Real estate | 1984 |
| Unity Connect Ltd | Administrative & support | 2021 |
| Unity Development Group Ltd | Construction | 2020 |
| Unity J Hospitality Ltd | Administrative & support | 2025 |
| Unity Legal Services Ltd | Professional & scientific | 2021 |
| Unity Logistics Ltd | Transport & logistics | 2015 |
| Unity PL C.I.C. | Hospitality | 2025 |
| Unity SIX Workshop Ltd | Manufacturing | 2021 |
| Unity Yoga Collective Ltd. | Arts & recreation | 2016 |
| Universal Alert Limited | Information & communication | 2022 |
| Universal Auto Works Limited | Wholesale & retail | 2025 |
| Universal Brand Limited | Wholesale & retail | 2004 |
| Universal Everything Limited | Information & communication | 2005 |
| Universal Everything Productions Limited | Information & communication | 2024 |
| Universal Farm Foods Limited | Wholesale & retail | 2026 |
| Universal Food, Beverage and Luxury Gift Packing Limited | Administrative & support | 2020 |
| Universal GAS Services (UK) Limited | Construction | 2002 |
| Universal GAS Services Holdings Limited | Construction | 2022 |
| Universal Glass Ltd | Mining & quarrying | 2023 |
| Universal Green Services Ltd | Energy | 2025 |
| Universal Pizza & Burger Limited | Hospitality | 2015 |
| Universal Properties (Northern) Limited | Real estate | 2017 |
| Universal Properties (Thurcroft) Limited | Real estate | 2017 |
| Universal Robots (UK) Ltd | Administrative & support | 2019 |
| Universal Spirits Limited | Administrative & support | 2010 |
| Universal Supply Limited | Wholesale & retail | 1999 |
| Universal Ways Store Ltd | Wholesale & retail | 2022 |
| Universe Events Ltd | Arts & recreation | 2020 |
| Universe Works RTM Company Limited | Households | 2025 |
| Univolv Partners Ltd | Professional & scientific | 2025 |
| Uniwell Pharma UK Limited | Wholesale & retail | 2025 |
| Unknown Publisher Limited | Information & communication | 2014 |
| UNL Music Ltd | Professional & scientific | 2024 |
| Unlock Tuition Limited | Education | 2025 |
| Unmusic Limited | Information & communication | 2017 |
| UNO Limited | Information & communication | 2014 |
| Unosand UK Limited | Manufacturing | 2005 |
| Unovo Limited | Information & communication | 2025 |
| Unravel Support Ltd | Health & social care | 2016 |
| Unrent UK Ltd | Information & communication | 2019 |
| Unsco Limited | Professional & scientific | 1959 |
| Unserious Labs Ltd | Information & communication | 2024 |
| Unstable Object Ltd | Information & communication | 2022 |
| Untamed Works Ltd | Information & communication | 2023 |
| Unwrapped Ltd | Wholesale & retail | 2017 |
| UOS LP Limited | Financial services | 2015 |
| UP & Away Events Ltd | Hospitality | 2021 |
| UP North Renovations Limited | Construction | 2024 |
| UP on the Tables Limited | Wholesale & retail | 2022 |
| UP Rite Partitions (Developments) Limited | Construction | 2007 |
| UP4OUR! Ltd | Wholesale & retail | 2025 |
| Upaclick Limited | Wholesale & retail | 2026 |
| Upcode Ltd | Administrative & support | 2020 |
| Upduck Design Ltd | Professional & scientific | 2025 |
| Upgraded Films UK Limited | Information & communication | 2022 |
| Uphill Driving School Ltd | Education | 2026 |
| Uplift Fitness and Coaching Ltd | Education | 2024 |
| Uplift South Yorkshire CIC | Other services | 2025 |
| Uplisting Limited | Information & communication | 2016 |
| Upliv Ltd | Real estate | 2025 |
| Upmyhealth Ltd | Health & social care | 2023 |
| Upnorf Ltd | Hospitality | 2023 |
| Upper Decks Management Company Limited | Real estate | 2001 |
| Upper Denby Developments Ltd | Construction | 2023 |
| Upper Noodle Limited | Hospitality | 2025 |
| Upperhurstdotcom Limited | Information & communication | 2011 |
| Upperthorpe & Netherthorpe Healthy Living Centre Trust | Administrative & support | 2001 |
| Upperthorpe Continental Food Store Limited | Wholesale & retail | 2018 |
| Upperthorpe Food Ltd | Hospitality | 2025 |
| Upright Bespoke Carpentry Ltd | Manufacturing | 2024 |
| Upside Accountancy Ltd | Information & communication | 2025 |
| Upton Interiors Limited | Construction | 2023 |
| Upton Partitions Ltd | Construction | 2019 |
| Uptown Barber S20 Ltd | Other services | 2022 |
| Upwordz Ltd | Administrative & support | 2016 |
| UQ Optics Limited | Wholesale & retail | 2024 |