| Andrew DEY Limited | Professional & scientific | 2016 |
| Andrew Gifford Art Limited | Wholesale & retail | 2025 |
| Andrew Huggett Ltd. | Information & communication | 2015 |
| Andrew Lintott and Associates Limited | Agriculture & fishing | 1998 |
| Andrew Maintenance Ltd | Construction | 2017 |
| Andrew Neil Associates Limited | Professional & scientific | 2009 |
| Andy HAU Associates Ltd | Professional & scientific | 2013 |
| Anema E Core Limited | Hospitality | 2014 |
| Anemoi Risk Management Ltd | Professional & scientific | 2024 |
| Angel Beauty Salon Ltd | Other services | 2024 |
| Angel Construction Sussex Limited | Construction | 2023 |
| Angel Hair (UK) Limited | Other services | 2012 |
| Angel Haulage Ltd | Transport & logistics | 2015 |
| Angel Media Services Ltd | Education | 2020 |
| Anglia Orthodontics Limited | Health & social care | 2018 |
| Anglo Advanced Materials Limited | Extraterritorial | 2011 |
| Anglo Galleon International Ltd | Transport & logistics | 2019 |
| Anglo Pacific Minerals Limited | Administrative & support | 1993 |
| Angus House (Eastbourne) Company Limited | Hospitality | 2015 |
| Ani.Nails Ltd | Other services | 2024 |
| Animals at Home (East Sussex) Ltd | Other services | 2012 |
| Anisky Limited | Financial services | 2024 |
| Anisky Property Solutions Limited | Real estate | 2026 |
| Anita Chopra Consultancy Ltd | Professional & scientific | 2019 |
| Anita's Beauty Works Limited | Other services | 2003 |
| Anna Eraut Limited | Professional & scientific | 2025 |
| Anniemations Limited | Information & communication | 2006 |
| Anouska Tamony Ltd. | Professional & scientific | 2015 |
| Ansh Soni Limited | Wholesale & retail | 2014 |
| Anson Willow Property Company Limited | Real estate | 2024 |
| Answertime Ltd | Information & communication | 2024 |
| Antares Cyber Security Ltd | Information & communication | 2023 |
| Anthony Brickwork Limited | Construction | 2000 |
| Anthony Brickwork Southern Limited | Construction | 2009 |
| Antogo Ltd | Health & social care | 2014 |
| Antony Miles Limited | Administrative & support | 2006 |
| Anume Limited | Professional & scientific | 2012 |
| Anusha Real Estate Ltd | Real estate | 2023 |
| Anuyogen Ltd | Wholesale & retail | 2025 |
| Anviet Cuisine Ltd | Hospitality | 2022 |
| Anvil London Limited | Construction | 2016 |
| AO Car Sales Ltd | Wholesale & retail | 2026 |
| AP Brickwork and Landscaping Ltd | Administrative & support | 2025 |
| AP Primary Care Consultancy Ltd | Professional & scientific | 2025 |
| Ap-It Services Limited | Information & communication | 2025 |
| Aparimita Global Ltd | Wholesale & retail | 2026 |
| Apex Advanced Products Limited | Professional & scientific | 2024 |
| Apex Car Rental PLC | Administrative & support | 1987 |
| Apex Convenience Stores Ltd | Wholesale & retail | 2012 |
| Apex Core Limited | Professional & scientific | 2009 |
| Apex Electronic Solutions Limited | Professional & scientific | 2009 |
| Apex Park M.C. Limited | Other services | 1992 |
| Apexbridge Recruitment Ltd | Administrative & support | 2025 |
| APF Dental Practice Limited | Health & social care | 2022 |
| Aphra Shemza Limited | Arts & recreation | 2024 |
| Apiject Limited | Professional & scientific | 2015 |
| Apple Installations Ltd | Information & communication | 2025 |
| Apple Tree Events Limited | Hospitality | 2013 |
| Apple Way Ltd | Real estate | 2015 |
| Applied Healthcare Solutions Limited | Information & communication | 2010 |
| Applied Vision Limited | Professional & scientific | 2026 |
| Applyflow Technologies (UK) Limited | Information & communication | 2017 |
| Appropel Limited | Information & communication | 2023 |
| Appropriate Application Limited | Extraterritorial | 1995 |
| APR Automation Limited | Other services | 2015 |
| APW Futures Limited | Financial services | 2020 |
| Aqari Limited | Health & social care | 2024 |
| Aqua EYE Media CIC | Information & communication | 2023 |
| Aquatics Limited | Agriculture & fishing | 1996 |
| Aquila Cleaners Limited | Administrative & support | 2025 |
| AR Rahman Cafe Limited | Hospitality | 2022 |
| Aras Cafe Ltd | Hospitality | 2026 |
| Arboles Properties Ltd | Real estate | 2021 |
| ARC Brickwork and Building Limited | Construction | 2015 |
| ARC Brickwork and Development Ltd | Construction | 2023 |
| ARC Orthodontics Limited | Health & social care | 2008 |
| ARC UK Property Investments Ltd | Real estate | 2026 |
| Arcadia Cigars Hove Limited | Extraterritorial | 2024 |
| Arcadia Objects Limited | Wholesale & retail | 2023 |
| Arcadia Premises Limited | Real estate | 2025 |
| Arcem Investments Ltd | Real estate | 2025 |
| Arch Developers Ltd | Construction | 2022 |
| Arch Mews Limited | Construction | 2022 |
| Archer & Partners Limited | Real estate | 2003 |
| Archer Electrics Limited | Construction | 2008 |
| Architectural Computer Services Limited | Information & communication | 2015 |
| Archjo Ltd | Professional & scientific | 2013 |
| Archman Property Limited | Real estate | 2022 |
| Ardarragh Mansions (Eastbourne) Limited | Real estate | 2005 |
| Arden Green Management Limited | Professional & scientific | 2011 |
| Arden Mead (Eastbourne) Freehold Company Limited | Households | 2015 |
| Ardentia Ltd | Extraterritorial | 2018 |
| Ardnusbridge Investments Limited | Real estate | 1963 |
| Arete Ventures Limited | Health & social care | 2017 |
| ARF Property Ltd | Real estate | 2016 |
| Arfy Limited | Real estate | 2020 |
| Aristocutz Limited | Other services | 2007 |
| ARK Private Ltd | Wholesale & retail | 2016 |
| ARK Supplies Ltd | Wholesale & retail | 2016 |
| Arkham Auto Films Limited | Wholesale & retail | 2026 |