| Air Compressor Services (Worcs) Limited | Manufacturing | 2016 |
| Air Technology Systems Limited | Construction | 1992 |
| Airtech Insulation Ltd | Construction | 2017 |
| Airware International Limited | Wholesale & retail | 1993 |
| AJ 247 Plumbing & Heating Services Ltd | Construction | 2025 |
| AJ Brewer Associates Limited | Professional & scientific | 2016 |
| AJB Sports in Education Limited | Education | 2017 |
| Ajis Capital Limited | Financial services | 2011 |
| AJR Design Solutions Limited | Professional & scientific | 2012 |
| AJW Consulting Solutions Ltd | Professional & scientific | 2023 |
| Ak.Ngh. Limited | Wholesale & retail | 2026 |
| Akari Jewellery Limited | Wholesale & retail | 2026 |
| AKB (Holdings) Limited | Real estate | 1999 |
| Aksc Limited | Information & communication | 2014 |
| AL Build Limited | Construction | 2021 |
| AL Fahidi Glaxy Gold Ltd | Wholesale & retail | 2026 |
| AL Laites Ltd | Information & communication | 2025 |
| AL Pilates Limited | Arts & recreation | 2025 |
| Alan Ward Limited | Wholesale & retail | 1975 |
| Albion Road Properties Limited | Real estate | 2014 |
| Albor Productions Limited | Information & communication | 2015 |
| Alcea Consulting Limited | Professional & scientific | 2017 |
| Alcock Architecture Ltd | Professional & scientific | 2025 |
| Alcott Limited | Administrative & support | 1991 |
| Aldea Blanca 1 Limited | Professional & scientific | 2002 |
| Alderwood Property Services Limited | Real estate | 2001 |
| Alderworth Trade Limited | Wholesale & retail | 2026 |
| Aldham Properties Limited | Real estate | 1980 |
| Aleon Estates Limited | Real estate | 2021 |
| Alessandra Design Limited | Information & communication | 2025 |
| Alexa Interiors Ltd | Wholesale & retail | 2025 |
| Alexander Maintenance Contractors Limited | Administrative & support | 2021 |
| Alexander Technology and Media Limited | Information & communication | 2018 |
| Alice Wheeler Limited | Wholesale & retail | 2019 |
| ALL & Sundry Productions | Arts & recreation | 2014 |
| ALL 4 One (UK) Limited | Professional & scientific | 2008 |
| ALL 4 One Engineering Ltd | Manufacturing | 2004 |
| ALL 4 One Holdings (Bromsgrove) Limited | Financial services | 2019 |
| ALL Dressed UP Limited | Arts & recreation | 2024 |
| ALL PAW One Canine Services Ltd | Other services | 2021 |
| ALL Saints Management Company Limited | Households | 2004 |
| All-Tech (Midlands) Limited | Manufacturing | 1999 |
| Allmet (UK) Ltd | Wholesale & retail | 2024 |
| Allsaint Leisure Property Ltd | Real estate | 2020 |
| Allsquare Property Ltd | Households | 2025 |
| Allum Holdings Group Limited | Financial services | 2026 |
| Allum Motor Fleet Limited | Administrative & support | 2026 |
| ALM Building Ltd | Construction | 2025 |
| ALN Circuits Ltd | Manufacturing | 1992 |
| Alpha Cctv Systems Ltd | Administrative & support | 2020 |
| Alpha Commercial Management Ltd | Professional & scientific | 2023 |
| Alpha Facilities Group Limited | Construction | 2008 |
| Alpha IT Training Ltd | Information & communication | 2007 |
| Alpha Leisure Limited | Wholesale & retail | 2009 |
| Alscot Timber & Woodworking Supplies Limited | Manufacturing | 2002 |
| Alsm Contracts Limited | Transport & logistics | 2023 |
| Alstertor Rail UK Limited | Professional & scientific | 2002 |
| Altavista Ltd | Other services | 2021 |
| Altavista Project Management Ltd | Administrative & support | 2019 |
| Altcreate Ltd | Information & communication | 2025 |
| Altitude Imagery Ltd | Information & communication | 2024 |
| Alton Creative Ltd | Professional & scientific | 2024 |
| Aluminium Packaging Recycling Organisation | Water & waste | 1993 |
| Aluna Entertainment Limited | Arts & recreation | 2021 |
| Aluna Vision Limited | Arts & recreation | 2021 |
| Alupro Limited | Extraterritorial | 1998 |
| Alyson Orthodontics Ltd | Health & social care | 2019 |
| AM Allure Ltd | Other services | 2022 |
| AM Oral Surgery Solutions Ltd | Health & social care | 2016 |
| Amalgamated Conglomerate Limited | Information & communication | 2015 |
| Amand Vest Ltd | Health & social care | 2022 |
| Amarod Pipe Services Limited | Administrative & support | 2012 |
| AMB Telecoms Ltd | Information & communication | 2007 |
| Amber Care Centre Limited | Other services | 2004 |
| Amber Contracts Limited | Manufacturing | 2005 |
| Amber Treasure Holdings Limited | Financial services | 2015 |
| Ambex Group Limited | Financial services | 1994 |
| Amelias Advanced Aesthetics Ltd | Other services | 2026 |
| American Candy Super Store Ltd | Wholesale & retail | 2023 |
| Amigo SKI Limited | Administrative & support | 2013 |
| Amika International Limited | Wholesale & retail | 2019 |
| Amina Limited | Arts & recreation | 2026 |
| Amos Building Supplies Limited | Wholesale & retail | 2025 |
| Amplify Technology Limited | Information & communication | 2023 |
| Amsm Property Limited | Real estate | 2025 |
| AMW Contractors UK Ltd | Construction | 2021 |
| AMW ME Ltd | Construction | 2026 |
| Amylac Trading Ltd | Wholesale & retail | 2025 |
| An&P Limited | Administrative & support | 2026 |
| Anarkali Takeaway Limited | Hospitality | 2024 |
| Anatyne Ltd | Information & communication | 2026 |
| AND Products Limited | Manufacturing | 2019 |
| Anderson Day Consultants Limited | Administrative & support | 2024 |
| Anderson Milroy Contracts Limited | Construction | 2018 |
| Andrew Colson Training & Safeguarding Services Ltd | Public administration | 2025 |
| Andrew Hickman Limited | Professional & scientific | 2019 |
| Andrew James Financial Services Limited | Professional & scientific | 2025 |
| Angel Cover Ltd | Administrative & support | 2021 |
| Animation 2000 Limited | Information & communication | 1973 |
| Anmol Mart Ltd | Wholesale & retail | 2025 |