| Alasco Limited | Construction | 2017 |
| Albanna Limited | Health & social care | 2005 |
| Albany Design | | 1993 |
| Albany Graphics | | 1996 |
| Albert Villa Property Limited | Real estate | 2002 |
| Albion Records | Arts & recreation | 2005 |
| Aleam Analytical Limited | Professional & scientific | 2020 |
| Alexander Close Management Company Limited | Households | 2022 |
| Alexander Consulting (Kent) Limited | Professional & scientific | 2004 |
| Alexander Hobbs Limited | | 1987 |
| Alexy Angel Limited | Administrative & support | 2004 |
| Alford Brothers (Folkestone) Limited | Wholesale & retail | 1966 |
| Alfred Day and SON (Headcorn) Limited | Agriculture & fishing | 1950 |
| ALI Baba's Cafe Ltd | Hospitality | 2022 |
| Alibert Properties Limited | Real estate | 2007 |
| Aligned Contracts Ltd | Construction | 2026 |
| Alison Marks Swim School Limited | Health & social care | 2006 |
| Aliunde Limited | Financial services | 2005 |
| ALL Seasons Windows (Kent) Limited | Construction | 2002 |
| Allen Peach Associates | | 1994 |
| Alltech Trans Limited | Professional & scientific | 2002 |
| Alltime Securities Limited | Construction | 1960 |
| Allum Building Services Limited | Construction | 2005 |
| Alma Global Consultancy Limited | Education | 2026 |
| Alma Registrars Limited | Professional & scientific | 1983 |
| Almari Ltd | Professional & scientific | 2025 |
| Almic Group Ltd | Construction | 2012 |
| Almondbeech Limited | Wholesale & retail | 2002 |
| Alpacian (UK) Limited | Real estate | 2025 |
| Alpha Beta Electrical Services Limited | Construction | 2006 |
| Alpha R F Limited | Manufacturing | 1998 |
| Alphatrace Limited | Construction | 2003 |
| Alronire Limited | Information & communication | 2006 |
| Altrad MTD Limited | Construction | 1987 |
| AM Mortgage & Financial Services Limited | Financial services | 2003 |
| Am:Pm Creative Limited | Extraterritorial | 2004 |
| Amacare Limited | Other services | 2005 |
| Amalgam Building Consultants Limited | Professional & scientific | 2004 |
| Aman Property Investments Limited | Real estate | 2002 |
| Amazing Grace Support Services Ltd | Health & social care | 2020 |
| Ambareen Estates Ltd | Real estate | 2016 |
| Amber Drafting Services Limited | Professional & scientific | 1994 |
| Amber Physiotherapy Services Limited | Health & social care | 1999 |
| Amber Woodhouse Equestrian Ltd | Other services | 2024 |
| Amberlay Limited | Professional & scientific | 2004 |
| Ambion Scotland Limited | | 1973 |
| Amerequus Limited | Administrative & support | 2003 |
| Amethyst Health Limited | Health & social care | 2024 |
| Amha Limited | Real estate | 2003 |
| Amherst Resources Limited | Professional & scientific | 1998 |
| Amin Corporation Limited | Wholesale & retail | 2017 |
| Amphenol Commercial and Industrial UK, Limited | Professional & scientific | 1997 |
| Amphenol Holding UK, Limited | Professional & scientific | 1997 |
| Amphenol-Borg Limited | Professional & scientific | 1957 |
| Amphenol-Borg Pension Trustees Limited | Professional & scientific | 1977 |
| Amplio Group Limited | Construction | 2025 |
| Amsj & Co Limited | Professional & scientific | 2020 |
| Amycleanhouse Limited | Administrative & support | 2023 |
| An-Elec Services Limited | Construction | 2000 |
| ANA Site Engineering Services Limited | Construction | 2004 |
| Andrade Properties Limited | Real estate | 2013 |
| Andrew Boyle Associates Limited | Professional & scientific | 1997 |
| Andrews Contractors Limited | Construction | 2007 |
| Andrews Timber Limited | Wholesale & retail | 2000 |
| Andy's Lockers Limited | Wholesale & retail | 2026 |
| Angela Mead Limited | Professional & scientific | 2007 |
| Anglo Consulting Limited | Information & communication | 2000 |
| Anglo Management Assets LLP | | 2023 |
| Anglo Management Holdings UK Limited | Other services | 2023 |
| Anglo Properties Limited | Real estate | 1993 |
| Angy Care Health Foundation Limited | Health & social care | 2023 |
| Anifler Limited | Wholesale & retail | 2025 |
| Animals at Home (NW Kent) Ltd | Other services | 2005 |
| Anish Sharma Wealth Management Limited | Financial services | 1984 |
| Anna Mapp Chiropody Limited | Health & social care | 2002 |
| Annasam Limited | Professional & scientific | 2023 |
| Annex Activities Limited | Professional & scientific | 1998 |
| Anpu Trading Company Ltd | Wholesale & retail | 2024 |
| Ansley Construction Limited | Professional & scientific | 1975 |
| Anterco Limited | Real estate | 1982 |
| Anthaven Limited | Professional & scientific | 1988 |
| Anthology Services Ltd | Extraterritorial | 2003 |
| Anthony Cowie Limited | Wholesale & retail | 2003 |
| Anthony Edwin Limited | Arts & recreation | 2003 |
| Anthony Hicks Limited | Construction | 2003 |
| Anthony Pratt Fine Arts Limited | Other services | 1991 |
| Anton Freight Limited | | 1983 |
| Antoniou Hair Fashions Limited | Other services | 1968 |
| Ants Estates Limited | Real estate | 2025 |
| Anvex Construction Limited | Wholesale & retail | 1987 |
| AOA Ventures Limited | Real estate | 2017 |
| AP Control Limited | Professional & scientific | 2019 |
| AP Great Retail Ltd | Wholesale & retail | 2013 |
| Apex Designs Digital Ltd | Professional & scientific | 2018 |
| Apex Embalming Services Limited | Other services | 2002 |
| Apexaiq Ltd. | Information & communication | 2023 |
| Apion Limited | Information & communication | 2005 |
| Apogee Managed Services International Limited | Financial services | 2022 |
| Apollo Autos (Snodland) Limited | Wholesale & retail | 2007 |
| Apollo Data Limited | Information & communication | 1993 |