| Uniq Catering Services Ltd | Manufacturing | 2026 |
| Unique Hair Design Limited | Other services | 2007 |
| Unique Regalia Ltd | Wholesale & retail | 2016 |
| Unique Wall Art Ltd | Wholesale & retail | 2020 |
| Unison UK Opco Limited | Professional & scientific | 2022 |
| Unit 4 MOT & Service Center Cwmbran Ltd | Wholesale & retail | 2025 |
| Unit 4 MOT & Service Center Limited | Wholesale & retail | 2023 |
| Uniteach Limited | Administrative & support | 2011 |
| United Care Group Limited | Health & social care | 2020 |
| United Care Holdings Limited | Health & social care | 2021 |
| United Care Solutions Ltd | Health & social care | 2020 |
| United Engineering Associates Limited | Manufacturing | 1991 |
| United Foods (S. Wales) Ltd | Wholesale & retail | 2015 |
| United Kingdom Gymnastics Association Limited | Other services | 2002 |
| United Pathways Group Limited | Professional & scientific | 2023 |
| United Properties (NPT) Ltd | Real estate | 2019 |
| Unity Contractors Ltd | Construction | 2025 |
| Unity Hair Limited | Other services | 2022 |
| Unity Transport Solution Ltd | Transport & logistics | 2024 |
| Universal Associated Limited | Wholesale & retail | 2019 |
| Universal Spring & Pressings Limited | Manufacturing | 1987 |
| Universal Trading Centre Limited | Transport & logistics | 2020 |
| Universal Waste Recycling Limited | Water & waste | 2012 |
| Unquiet Media Limited | Information & communication | 2018 |
| Unseen Caffeine Ltd | Wholesale & retail | 2020 |
| Unseen Motions Ltd | Information & communication | 2015 |
| UP and Away Media Ltd | Professional & scientific | 2025 |
| Upbeat Music and Arts Service Ltd | Education | 2013 |
| Upcycled Plant Power (UPP) Ltd | Manufacturing | 2022 |
| Updraft WP Software Limited | Information & communication | 2013 |
| Upper Bar Newport Management Company Limited | Real estate | 2009 |
| Upper Chine Developments Limited | Construction | 2011 |
| Upsa-Daisy Day Nursery Limited | Education | 2006 |
| Upscale+ Limited | Health & social care | 2022 |
| Upstart Homes Limited | Construction | 2018 |
| Urban Energy Ltd | Construction | 2018 |
| Urban Illustrate Ltd | Professional & scientific | 2007 |
| Urban Metal and Waste Recycling Limited | Water & waste | 2023 |
| Urban Metro Gym Limited | Arts & recreation | 2003 |
| Urban Podcasts Ltd | Professional & scientific | 2023 |
| Urban Retreat Ventures Limited | Professional & scientific | 2007 |
| Urban Roots Homes Ltd | Real estate | 2026 |
| Urban Rugs UK Padded Prayer MAT Ltd | Wholesale & retail | 2025 |
| Urban Way Ltd | Wholesale & retail | 2025 |
| Urbane Interiors Limited | Professional & scientific | 2018 |
| Urbanechoexpress Limited | Transport & logistics | 2025 |
| Ureka Global Holdings Ltd | Manufacturing | 2021 |
| Ureka Global Ltd | Manufacturing | 2013 |
| Urovasc Limited | Health & social care | 2020 |
| Urqhart Ltd | Professional & scientific | 2015 |
| Urquhart Carey Limited | Financial services | 2016 |
| Urquhart Holdings Ltd | Arts & recreation | 2018 |
| US Trading Newport Ltd | Wholesale & retail | 2025 |
| USB Vessel Supplies Ltd | Wholesale & retail | 2019 |
| Used Cars of South Wales Limited | Wholesale & retail | 2020 |
| Usedcarbuyerhub Ltd | Wholesale & retail | 2025 |
| USK Associates Limited | Administrative & support | 2015 |
| USK Boarding Kennels & Cattery Limited | Other services | 2012 |
| USK Land Limited | Construction | 2007 |
| USK Properties Limited | Real estate | 1995 |
| USK Vale Properties (Wales) Limited | Real estate | 1997 |
| USK Vale Properties Limited | Real estate | 1995 |
| USK Valley Cheese Company Limited | Manufacturing | 2025 |
| USK Valley Groundworks and Plant Hire Limited | Construction | 2022 |
| USK Valley Scaffolding & Plant Training Ltd | Administrative & support | 2009 |
| Uskside Wholesale Limited | Hospitality | 2025 |
| Uskvale Mews Management Company Limited | Households | 1988 |
| Ustura Baba Ltd | Other services | 2023 |
| USV Service Ltd | Construction | 2023 |
| Utaas Ltd | Wholesale & retail | 2022 |
| Utility GAS Solutions Ltd | Construction | 2020 |
| Utopia Empire Ltd | Other services | 2022 |
| Utopia Hair & Beauty Salon Ltd | Other services | 2017 |
| Utopia Merchant Services Limited | Other services | 2019 |
| Utopium London Limited | Administrative & support | 2012 |
| Uvin’S Limited | Wholesale & retail | 2025 |
| Uwin Prizes Limited | Administrative & support | 2024 |
| V & F PUB Management & Catering Ltd | Hospitality | 2019 |
| V & U Enterprise Ltd | Wholesale & retail | 2011 |
| V Goldstone Hospitality Ltd | Hospitality | 2024 |
| V Lovett Limited | Real estate | 2020 |
| V&A Films Limited | Information & communication | 2015 |
| V'Nillapod Cafe Limited | Hospitality | 2014 |
| Vale Consultancy Ltd | Professional & scientific | 2023 |
| Valecore Limited | Professional & scientific | 2026 |
| Valentino & Finch Ltd | Wholesale & retail | 2016 |
| Valerie Ballorin Limited | Professional & scientific | 2016 |
| Validient Ltd | Information & communication | 2021 |
| Valion Motors Ltd | Wholesale & retail | 2024 |
| Valley Plumbing Services Ltd | Construction | 2026 |
| Valley's Support Services Ltd | Health & social care | 2006 |
| Valley-Campers Ltd | Administrative & support | 2022 |
| Valleys Reclamation DR Limited | Wholesale & retail | 2025 |
| Valu Advisory Ltd | Financial services | 2020 |
| Value Added Education Ltd | Education | 2012 |
| Value People Ltd. | Professional & scientific | 2014 |
| Value People Property Ltd | Real estate | 2014 |
| Vandelay Industries Ltd | Professional & scientific | 2026 |
| Vanilla Haus Holdings Limited | Real estate | 2023 |
| Vanity Nails & Beauty Treatments Limited | Other services | 2026 |