| Unbrand Clothing Ltd | Transport & logistics | 2019 |
| Unchained Warrior Limited | Information & communication | 2016 |
| Uncle LAT Limited | Real estate | 2023 |
| Uncooked Fish Limited | Hospitality | 2017 |
| Under RAP Limited | Extraterritorial | 2015 |
| Under the BED Theatre Ltd | Arts & recreation | 2023 |
| Under the Bonnet Ltd | Wholesale & retail | 2011 |
| Under the Hard HAT, Behind the Mask Ltd | Information & communication | 2026 |
| Underhill Aviation Ltd | Wholesale & retail | 2023 |
| Underwood & SON Services Ltd | Construction | 2018 |
| Underwoods Surveyors (Northampton) Limited | Professional & scientific | 2024 |
| Undisputed Lounge Limited | Hospitality | 2025 |
| Unfair Marketing Advantages Ltd | Professional & scientific | 2016 |
| Unfold AI Limited | Professional & scientific | 2023 |
| Unfold Education C.I.C. | Education | 2020 |
| Unforgiving Minute Limited | Professional & scientific | 2011 |
| UNH Ltd | Wholesale & retail | 2014 |
| Uni:Dos Limited | Professional & scientific | 2016 |
| Unico Suites Ltd | Hospitality | 2026 |
| Unified Dance Limited | Health & social care | 2025 |
| Uniglass Limited | Wholesale & retail | 1989 |
| Union Cars Limited | Transport & logistics | 2014 |
| Union Foods Limited | Manufacturing | 2009 |
| Union Specialties UK Ltd | Manufacturing | 2011 |
| Union View Management Company Limited | Households | 2017 |
| Unique Finishes Limited | Construction | 2019 |
| Unique Roofing Specialists Ltd | Construction | 2024 |
| Unique Trader & Retailers Ltd | Wholesale & retail | 2014 |
| Uniquely Created Nutrition and Health Ltd | Health & social care | 2020 |
| Unis Group Ltd. | Other services | 2016 |
| Unisan Europe Holding Company Limited | Financial services | 2018 |
| Unit 17 Dance and Performing Arts Limited | Arts & recreation | 2010 |
| Unite 1ST Investment Limited | Financial services | 2023 |
| Unite Brothers Limited | Professional & scientific | 2023 |
| Unite Deliveries Ltd | Transport & logistics | 2021 |
| Unite Foods Limited | Hospitality | 2023 |
| Unite Productions UK Ltd | Arts & recreation | 2020 |
| United Delivery Ltd | Transport & logistics | 2017 |
| United Dental Limited | Health & social care | 2013 |
| United ESP Ltd | Agriculture & fishing | 2022 |
| United Insight Limited | Transport & logistics | 2019 |
| United Practices Accountancy Ltd | Professional & scientific | 2007 |
| United Trade Contractors Ltd | Construction | 2024 |
| Unitedfmmt Ltd | Health & social care | 2026 |
| Unity & Social Ltd | Professional & scientific | 2022 |
| Unity Sports League Limited | Education | 2025 |
| Unitycarehome Ltd | Health & social care | 2025 |
| Unitycart Ltd | Wholesale & retail | 2025 |
| Unitymarket Ltd | Wholesale & retail | 2026 |
| Universal Environmental (Information) Access Limited | Professional & scientific | 2012 |
| Universal General Suppliers Ltd | Administrative & support | 2011 |
| Universal Playground Community Interest Company | Education | 2025 |
| Unlocking Property Potentials Ltd | Real estate | 2023 |
| Unmatched Coaching Ltd | Education | 2021 |
| Unora Healthcare Limited | Health & social care | 1992 |
| Unshackle CIC | Public administration | 2019 |
| UNT Construction Ltd | Construction | 2017 |
| UNT Interiors Ltd | Construction | 2019 |
| Untamed Nutrition Ltd | Manufacturing | 2026 |
| Untold Gaming Limited | Other services | 2020 |
| Unusual Media Limited | Information & communication | 2015 |
| UON Consultancy Ltd | Information & communication | 2018 |
| UP ALL Night Limited | Hospitality | 2009 |
| UP the Yard Limited | Agriculture & fishing | 2024 |
| Upbeat Image Limited | Information & communication | 2022 |
| Upkeep Training Limited | Education | 2016 |
| Uplift Real Estate Ltd | Real estate | 2025 |
| Upndown Haulage Ltd | Transport & logistics | 2026 |
| Upper London Capital Markets Ltd | Professional & scientific | 2012 |
| Upper Wensleydale Property Services Ltd | Construction | 2022 |
| Uppingham Properties Limited | Real estate | 2021 |
| Upsurge Scaffolding Ltd | Construction | 2026 |
| Upswing Holdings Limited | Financial services | 2022 |
| Upsycle Ltd | Wholesale & retail | 2022 |
| Uptakeai LLP | | 2024 |
| Uptimise Limited | Health & social care | 2024 |
| Upton E Residents Management Company Limited | Households | 2008 |
| Upton Grange Flats Management (NO 2) Limited | Households | 1998 |
| Upton Projects Limited | Professional & scientific | 2016 |
| UPWARD360 Ltd | Administrative & support | 2025 |
| Ur-Route Transport Limited | Transport & logistics | 2017 |
| Uragan Ltd | Construction | 2022 |
| Urban Aachra Ltd | Wholesale & retail | 2026 |
| Urban Build (Northampton) Limited | Real estate | 2025 |
| Urban Caterers Limited | Hospitality | 2025 |
| Urban Crowd Limited | Hospitality | 2003 |
| Urban Development Properties Ltd | Construction | 2024 |
| Urban Developments Northampton Ltd | Real estate | 2020 |
| Urban Estates Surveyors Limited | Professional & scientific | 2015 |
| Urban Fades Northampton Limited | Other services | 2021 |
| Urban Flame & Grill Ltd | Hospitality | 2025 |
| Urban Gardener Birmingham Ltd | Administrative & support | 2019 |
| Urban Home Supplies Ltd | Wholesale & retail | 2024 |
| Urban Integrated Ltd | Information & communication | 2017 |
| Urban Nest Renovations & Investments Ltd | Construction | 2026 |
| Urban Pixel Ltd | Wholesale & retail | 2024 |
| Urban Planet Ltd | Real estate | 2019 |
| Urban Spice Limited | Hospitality | 2026 |
| Urban-Luxe Trading Limited | Wholesale & retail | 2025 |
| Urbane People Limited | Administrative & support | 2018 |