| Ashfield Nursing Home Limited | Health & social care | 2003 |
| Ashfield Projects (Yorkshire) Ltd | Construction | 2017 |
| Ashfield Property Group Ltd | Real estate | 2015 |
| Ashley Sims Financial Planning Limited | Financial services | 2019 |
| Asil Systems Limited | Construction | 1985 |
| ASK and Consult Limited | Professional & scientific | 2024 |
| ASK Assets Ltd | Financial services | 2022 |
| ASK Medical Limited | Financial services | 2011 |
| ASK Sameday Couriers Ltd | Transport & logistics | 2018 |
| Askills Ltd | Professional & scientific | 2018 |
| Aslvista Ltd | Professional & scientific | 2020 |
| Aspin Physio Ltd | Health & social care | 2014 |
| Aspire Shine Construction Ltd | Construction | 2023 |
| Asquith Citygate LLP | | 2007 |
| Asri Landscape Limited | Administrative & support | 2020 |
| Asset Capital 44 Limited | Construction | 2022 |
| Asset Capital 44 Opco Limited | Households | 2025 |
| Asset Capital Group Holdings Limited | Financial services | 2024 |
| Asset Capital Investments Armley LLP | | 2025 |
| Asset Capital Investments LLP | | 2019 |
| Asset Capital Leeds City Resi Limited | Financial services | 2026 |
| Asset Capital Limited | Financial services | 2017 |
| Asset Capital Pottery Fields Limited | Real estate | 2025 |
| Assured Health and Protection Limited | Administrative & support | 2020 |
| Aston Wolf Thornton Limited | Professional & scientific | 2025 |
| Astralfactor Limited | Real estate | 1988 |
| Astutus Dynamic Solutions Ltd | Information & communication | 2022 |
| ATH Education Ltd | Arts & recreation | 2013 |
| ATH Medical Services Ltd | Health & social care | 2015 |
| Athena Law Services Ltd | Administrative & support | 2012 |
| ATK Building Solutions Ltd | Construction | 2019 |
| Atken Limited | Manufacturing | 2023 |
| Atomos Networks Ltd | Information & communication | 2014 |
| ATR Medical Ltd | Health & social care | 2022 |
| Atuin.Io Ltd | Professional & scientific | 2021 |
| Atuin.Ventures Ltd | Professional & scientific | 2020 |
| Aug-Corp Limited | Manufacturing | 2024 |
| Augean Incineration Limited | Extraterritorial | 2018 |
| Augean LFT Claims Co Limited | Extraterritorial | 2020 |
| Augean Limited | Professional & scientific | 2004 |
| Augean North Limited | Water & waste | 1998 |
| Augean Property Limited | Extraterritorial | 1999 |
| Augean South Limited | Water & waste | 2003 |
| Aurora Estates Ltd | Professional & scientific | 2014 |
| Austen Meek Ltd | Manufacturing | 2015 |
| Austinstall Limited | Construction | 2014 |
| Authentic PUB & Kitchens Ltd | Hospitality | 2022 |
| Author Design Ltd | Professional & scientific | 2023 |
| Auto-Lec Services Ltd | Extraterritorial | 2008 |
| Automatic Vending Association | Hospitality | 1994 |
| Autumnless Limited | Wholesale & retail | 2023 |
| Avenue BD Limited | Information & communication | 2020 |
| Aviator Property Limited | Real estate | 2007 |
| AW @MO Logistics Ltd | Transport & logistics | 2025 |
| AWC Facilities Management Ltd | Construction | 2020 |
| AWC Plant Hire Limited | Administrative & support | 2022 |
| AWC Project Services Limited | Construction | 2024 |
| AWC Staff Services Limited | Construction | 2020 |
| AWC Technical Services Ltd | Information & communication | 2025 |
| Awesome Holdings Limited | Financial services | 2016 |
| Axal Holdings Ltd | Real estate | 2019 |
| Axal Services Ltd | Construction | 2016 |
| Axiologik Limited | Information & communication | 2016 |
| Axis Accounts & Management Services Limited | Professional & scientific | 1995 |
| Axis Business Consultants Limited | Information & communication | 1987 |
| Ayin EL Kanna Limited | Health & social care | 2022 |
| Ayscough Inns Ltd | Hospitality | 2022 |
| Azora Jewellery Limited | Wholesale & retail | 2024 |
| Aztech Construction Limited | Construction | 2013 |
| B & B (Collingham) Limited | Professional & scientific | 2003 |
| B-Side Live Limited | Information & communication | 2020 |
| B. K. Growers Limited | Wholesale & retail | 1976 |
| B2 Spectrum Limited | Professional & scientific | 2017 |
| Baanrai Restauranat Ltd | Hospitality | 2021 |
| Babease With Jess Ltd | Health & social care | 2024 |
| Backyard Cricket Ltd | Information & communication | 2025 |
| BAE Coffee Holdings Ltd | Extraterritorial | 2023 |
| BAE Coffee Ltd | Hospitality | 2021 |
| BAE Pizza Ltd | Hospitality | 2022 |
| BAG of Tools Ltd | Wholesale & retail | 2016 |
| Baildon GAS Services Limited | Construction | 2018 |
| Bailey Court RTM Company Ltd | Households | 2018 |
| Bailey Purchasing Limited | Other services | 2023 |
| Baker & Morgan Construction Limited | Construction | 2019 |
| Balby Trans Limited | Transport & logistics | 2019 |
| Bank Top Garage (Wetherby) Limited | Wholesale & retail | 2009 |
| Bardsey Garage Doors Limited | Construction | 2018 |
| Bardsey Tree Services Ltd | Agriculture & fishing | 2007 |
| Bare Design 9 Ltd | Professional & scientific | 2022 |
| Barlow & Goldthorpe LLP | | 2011 |
| Barnaby Stewart Innovation Limited | Administrative & support | 2017 |
| Barnsley Profix Limited | Construction | 2013 |
| Bates Wealth Management Ltd | Financial services | 2023 |
| Baxter Dental Ltd | Health & social care | 2025 |
| Baycloud Systems Limited | Information & communication | 1997 |
| Bayford & Co Ltd | Real estate | 2003 |
| Bayford & Co. (Developments) Limited | Real estate | 1977 |
| Bayford Energy Bidco Limited | Financial services | 2020 |
| Bayford Energy Holdco Limited | Financial services | 2020 |
| BB Prop Ltd | Real estate | 2025 |