| Auraden Limited | Health & social care | 2015 |
| Aurelius Racing Limited | Agriculture & fishing | 2023 |
| Auric Southern Ltd | Wholesale & retail | 2016 |
| Auric Technology Solutions and Consultancy Limited | Information & communication | 2019 |
| Austin & Mclean Group Limited | Professional & scientific | 2011 |
| Austin French Ltd | Administrative & support | 2016 |
| Austra Associates Limited | Professional & scientific | 2019 |
| Auticue Ltd | Information & communication | 2025 |
| Auto Consortium Ltd | Wholesale & retail | 2024 |
| Auto Electrix - Ferndown Ltd | Manufacturing | 2022 |
| Auto Electrix Installations Ltd | Construction | 2024 |
| Auto Electrix Mobile Assist Ltd | Construction | 2020 |
| Auto Electronics (South) Limited | Information & communication | 2021 |
| Auto Repairs Limited | Wholesale & retail | 2018 |
| Autodents Limited | Wholesale & retail | 2002 |
| Autoed Ltd | Information & communication | 2026 |
| Autoglaze Holdings Limited | Financial services | 2025 |
| Autoglaze Limited | Wholesale & retail | 2001 |
| Autolock Security Systems Limited | Other services | 2002 |
| Automated IT Solutions Ltd | Information & communication | 2018 |
| Automechs Garage (Enfield) Limited | Wholesale & retail | 1972 |
| Automotive Body Repairs Ltd | Wholesale & retail | 2021 |
| Autovan Limited | Extraterritorial | 2006 |
| Autumn Accounts Limited | Professional & scientific | 2015 |
| Auvista Limited | Professional & scientific | 2024 |
| AV Dorset Supplies Limited | Wholesale & retail | 2026 |
| Avalor Ltd | Professional & scientific | 2018 |
| Avalow Limited | Professional & scientific | 2006 |
| Avant Garden Wimborne Ltd | Real estate | 2020 |
| Aveiro Enterprise Limited | Professional & scientific | 2022 |
| Avencia Accountants LLP | | 2016 |
| Avencia Tax and Accountancy Ltd | Professional & scientific | 2019 |
| Avenir Solutions Limited | Professional & scientific | 2025 |
| Averon Systems Ltd | Information & communication | 2026 |
| Aviation & Aerospace Direct Limited | Information & communication | 2021 |
| Avigation Limited | Information & communication | 2018 |
| Avila Advisory Ltd | Professional & scientific | 2026 |
| Avocado Consulting Limited | Information & communication | 2022 |
| Avoch Limited | Professional & scientific | 2022 |
| Avon Court Property Ltd | Households | 2018 |
| Avon Dairy Ltd | Wholesale & retail | 2020 |
| Avon Material Supplies (Holdings) Limited | Financial services | 2012 |
| Avon Material Supplies (Plant Hire) Limited | Administrative & support | 1999 |
| Avon Material Supplies (Transport) Limited | Transport & logistics | 2011 |
| Avon Material Supplies Limited | Mining & quarrying | 1993 |
| Avon Skips Limited | Administrative & support | 1999 |
| Avon Valley Developments Ltd. | Construction | 2013 |
| Avonbridge (South) Limited | Extraterritorial | 2004 |
| Avonwood Developments Limited | Manufacturing | 1990 |
| AVS DEV Limited | Professional & scientific | 2015 |
| AW Aero Consulting Limited | Professional & scientific | 2025 |
| AW Penguin Limited | Real estate | 2021 |
| AW Professional Services Limited | Administrative & support | 2022 |
| Awaken! Holdings Limited | Professional & scientific | 2018 |
| Awen Communication Services Ltd | Information & communication | 2020 |
| Awgmentor Consulting Ltd | Information & communication | 2017 |
| Awinya Ltd | Professional & scientific | 2016 |
| AWM Consultancy Services Limited | Professional & scientific | 2021 |
| AX Squared Limited | Information & communication | 2016 |
| AXD Properties Ltd | Real estate | 2026 |
| Axion IT Consultancy Limited | Information & communication | 2023 |
| Axis 51 Developments Limited | Construction | 2020 |
| Axis House Holdings Ltd | Financial services | 2018 |
| Axis House Ltd. | Manufacturing | 2018 |
| Axisworks Consulting Ltd | Information & communication | 2024 |
| AXL Consultancy Ltd | Information & communication | 2025 |
| AYS Property Holdings Ltd | Real estate | 2025 |
| AYS Skip Hire Ltd. | Transport & logistics | 1987 |
| Aytas Limited | Administrative & support | 2019 |
| Ayya Ltd | Information & communication | 2022 |
| AZ Business Solutions Ltd | Information & communication | 2022 |
| Azimuth Consulting Limited | Professional & scientific | 2022 |
| Aztrack Ltd | Information & communication | 2019 |
| Azure Engineering Limited | Information & communication | 2025 |
| B B S Accountants Limited | Professional & scientific | 2003 |
| B F Interiors Ltd | Construction | 2016 |
| B Giles Consulting Ltd | Information & communication | 2017 |
| B Protocols Ltd | Information & communication | 2024 |
| B R Consulting Limited | Information & communication | 2012 |
| B R Owen Consulting Limited | Professional & scientific | 2024 |
| B Stephens Consultant Ltd | Professional & scientific | 2022 |
| B T Hughes Consulting Limited | Professional & scientific | 2025 |
| B Tointon Electrical Ltd | Construction | 2016 |
| B&F Software Solutions Ltd | Information & communication | 2021 |
| B&G Associates (South) Ltd | Health & social care | 2019 |
| B-Side Music Therapy Ltd | Public administration | 2025 |
| B.Gasper Supplier Development & Procurement Partners (Bgsdp) Limited | Professional & scientific | 2026 |
| B3N Consulting Limited | Professional & scientific | 2016 |
| B3N Investments Limited | Real estate | 2020 |
| Back Garden Bubbles Ltd | Hospitality | 2021 |
| Badbury Developments Limited | Construction | 2004 |
| Badbury Holdings Limited | Financial services | 2021 |
| Badbury Investments Ltd | Real estate | 2022 |
| Badbury View Construction Ltd | Construction | 2016 |
| Badger Catering Limited | Wholesale & retail | 2008 |
| Badgers Court (Leavesden) Residents Limited | Administrative & support | 1994 |
| Badgersett Ltd | Real estate | 2022 |
| Badgerworks Ltd | Professional & scientific | 2020 |
| Baekr Limited | Information & communication | 2023 |
| BAG Store UK Ltd | Wholesale & retail | 2024 |