| Uncrewed Maritime Consulting Ltd | Professional & scientific | 2025 |
| Undercliffe Freehold Limited | Real estate | 1988 |
| Undercliffe Management Company Limited(The) | Households | 1986 |
| Underfloor Heating UK Limited | Extraterritorial | 2004 |
| Underwood Land Holdings Limited | Construction | 2021 |
| Undivided Heart Limited | Professional & scientific | 2024 |
| Uneedavan (UK) Limited | Transport & logistics | 2009 |
| UNG Services Ltd | Transport & logistics | 2025 |
| Uni-Let (East Anglia) Limited | Real estate | 1997 |
| Uni-Prop International Limited | Manufacturing | 2016 |
| Unico Shipping Ltd | Transport & logistics | 2023 |
| Unicoin Digital Capital Exchange Limited | Information & communication | 2019 |
| Unicorn Studios (Ipswich) Limited | Administrative & support | 2019 |
| Unicrest Marketing Limited | Real estate | 1993 |
| Unified Technology Ltd | Information & communication | 2000 |
| Uninor Ltd. | Professional & scientific | 2024 |
| Union Marine Chartering Ltd | Transport & logistics | 2021 |
| Union Secure Limited | Wholesale & retail | 2026 |
| Union Shopfrronts Ltd | Administrative & support | 2026 |
| Unique Building Supplies Limited | Construction | 2024 |
| Unique Homes Suffolk Ltd | Construction | 2025 |
| Unique Payroll Service Limited | Professional & scientific | 2013 |
| Unique West Ltd | Wholesale & retail | 2023 |
| Unit 3 Knightsdale Ltd | Real estate | 2026 |
| Unit T Ltd | Wholesale & retail | 2024 |
| Unite Networks Limited | Information & communication | 2023 |
| Unitech Communications Ltd | Information & communication | 2018 |
| Unitech Innovations Limited | Manufacturing | 2014 |
| Unitech Properties Limited | Real estate | 2017 |
| United Brothers Alliance CIC | Arts & recreation | 2023 |
| United Care Plus Support Solution Ltd | Health & social care | 2024 |
| United Kash Limited | Administrative & support | 2009 |
| United Spices Ltd | Wholesale & retail | 2023 |
| United West Ltd | Information & communication | 2013 |
| Uniting Sports Limited | Arts & recreation | 2025 |
| Unity Eats Ltd | Wholesale & retail | 2026 |
| Unity Sailing LLP | | 2022 |
| Unity Travel Holdings Limited | Transport & logistics | 2024 |
| Unity Travel Limited | Transport & logistics | 2011 |
| Universal Cabs Ltd | Transport & logistics | 2021 |
| Universal Consolidated Limited | Information & communication | 2024 |
| Universal Control Equipment Limited | Manufacturing | 1996 |
| Universal Converting Equipment Limited | Professional & scientific | 2000 |
| Universal Customs Clearance Ltd | Transport & logistics | 2020 |
| Universal Garage Limited | Professional & scientific | 2007 |
| Universal Lawyers Ltd | Professional & scientific | 2011 |
| Universal Property Limited | Wholesale & retail | 2018 |
| Universal Property Services Ltd | Construction | 2012 |
| Universal Removals Limited | Administrative & support | 2011 |
| Universal Seminars Ltd | Education | 2011 |
| University of Suffolk Dental CIC | Education | 2023 |
| University of Suffolk Ltd | Education | 2004 |
| University of Suffolk Students' Union | Other services | 2009 |
| Unlimited Homes Ltd | Real estate | 2023 |
| Unlimited Sky 747 Ltd | Transport & logistics | 2022 |
| Unlock My Life CIC | Education | 2022 |
| Unlocking ME Coaching Limited | Professional & scientific | 2021 |
| Unmask Your Potential Ltd | Professional & scientific | 2025 |
| Unscene Suffolk Limited | Arts & recreation | 2013 |
| Unscrambled Limited | Information & communication | 2010 |
| Unskipped Ltd | Professional & scientific | 2022 |
| Untellect Ltd | Information & communication | 2011 |
| Unwrapped & Refill Ltd | Wholesale & retail | 2020 |
| Uplands Management (2008) Limited | Households | 2007 |
| Uplinkman Ltd | Information & communication | 2013 |
| Upside Finance Ltd | Financial services | 2022 |
| Upstix Ventures LLP | | 2011 |
| Urban Combat Limited | Education | 2024 |
| Urban Datacomms Limited | Information & communication | 2017 |
| Urban Design & Graphics Ltd | Manufacturing | 2023 |
| Urban Hair Additions Ltd | Other services | 2021 |
| Urban Rooster Ltd | Wholesale & retail | 2016 |
| Urban Sign Products Limited | Manufacturing | 2010 |
| Urban Stay Relocation Ltd | Hospitality | 2025 |
| Urcc Engineering Limited | Professional & scientific | 2024 |
| Urologistics Ltd | Information & communication | 2016 |
| Uromed Limited | Health & social care | 2015 |
| Ursa Products and Services Ltd | Professional & scientific | 2021 |
| Urte Ltd | Transport & logistics | 2019 |
| US SS Tours Limited | Administrative & support | 2024 |
| Usamaa Ltd | Wholesale & retail | 2025 |
| Used Containers Limited | Professional & scientific | 2002 |
| Used Trucks Limited | Wholesale & retail | 2001 |
| Used Vans Limited | Professional & scientific | 2002 |
| Useers Limited | Extraterritorial | 2023 |
| Utel Limited | Extraterritorial | 2024 |
| UTF Drylining Limited | Construction | 2014 |
| Uthando & Nobuntu Ltd | Transport & logistics | 2022 |
| Utilities Services Group Limited | Manufacturing | 2026 |
| Utility & Building Information Modelling Ltd | Professional & scientific | 2013 |
| Utility Associates U.K. Ltd. | Professional & scientific | 2006 |
| UTZ Trans Ltd | Transport & logistics | 2025 |
| UUC Limited | Real estate | 2008 |
| Uvue Drones Ltd | Information & communication | 2018 |
| Uxbridge Business Improvement District Limited | Other services | 2015 |
| UYI Organisation Limited | Real estate | 2017 |
| Uzubegroup Ltd | Information & communication | 2025 |
| V & a Consultancy Ltd | Transport & logistics | 2017 |
| V & a Star Ltd | Transport & logistics | 2021 |
| V & MP Terminals & Accessories Ltd. | Wholesale & retail | 1999 |