| Alice Havard Limited | Health & social care | 2021 |
| Align Dental Services Limited | Health & social care | 2026 |
| Alkoomi Limited | Professional & scientific | 2005 |
| ALL About Abodes Ltd | Construction | 2021 |
| ALL About Words Ltd | Professional & scientific | 2018 |
| ALL About YOU (TAB) Ltd | Other services | 2025 |
| ALL Construction Environment Services Limited | Construction | 2003 |
| ALL Construction Environmental Building Services Limited | Construction | 2023 |
| ALL Decked OUT Eastbourne Ltd | Administrative & support | 2016 |
| ALL England Taekwon-Do Association CIC | Arts & recreation | 2018 |
| ALL Moves South East Limited | Transport & logistics | 2023 |
| ALL Nations Ministries College (Bristol) | Other services | 2005 |
| ALL Round Rentals Ltd | Administrative & support | 2026 |
| ALL Safe Environmental Ltd | Water & waste | 2019 |
| ALL SET to SEW Ltd | Wholesale & retail | 2024 |
| ALL Star Soccer Eastbourne LLP | | 2016 |
| ALL Stars Roofing Ltd | Construction | 2024 |
| ALL Things Analogue Ltd | Wholesale & retail | 2020 |
| All&Goo Ltd | Wholesale & retail | 2013 |
| Allan Chivers Electrical Limited | Construction | 2018 |
| Allchorn Maritime Limited | Extraterritorial | 2016 |
| Allchorn Pleasure Boats Limited | Extraterritorial | 2015 |
| Alliance Powered Solutions Ltd | Professional & scientific | 2020 |
| Allied Aviation Limited | Information & communication | 1998 |
| Allistone Commissioning Services Ltd | Construction | 2021 |
| Alltime UK Limited | Real estate | 2004 |
| Allure Salon Ltd | Other services | 2019 |
| Alnoor Medical Services Ltd. | Health & social care | 2014 |
| Alpha Chocolate Ltd | Hospitality | 2026 |
| Alpha Entertainment Limited | Hospitality | 2018 |
| Alpha Payrolls Limited | Professional & scientific | 1999 |
| Alphabet Admin Limited | Financial services | 2023 |
| Alphaguard Holdings Ltd | Real estate | 2021 |
| Alphaguard Security Services Limited | Administrative & support | 2024 |
| ALPHAGUARDK9 Limited | Administrative & support | 2007 |
| Alpinerose Limited | Extraterritorial | 1982 |
| Alps Supplements Ltd | Wholesale & retail | 2026 |
| Alqahtani Ltd | Administrative & support | 2017 |
| Altavita Associates Ltd | Administrative & support | 2020 |
| Alter Aspect Ltd | Information & communication | 2026 |
| Altin Handyman Ltd | Construction | 2023 |
| Altus Health & Performance Ltd | Wholesale & retail | 2025 |
| Altvan Limited | Wholesale & retail | 2023 |
| Alumhurst Hotel Limited | Hospitality | 2026 |
| Aluna House Ltd | Manufacturing | 2026 |
| Alunia Construction Ltd | Construction | 2022 |
| Alveon Limited | Health & social care | 2026 |
| Alves Rowe Ltd | Construction | 2025 |
| Alwali Portfolio Limited | Real estate | 2023 |
| Alzabin Ltd | Professional & scientific | 2021 |
| AM Sports Health Limited | Arts & recreation | 2025 |
| Amack Group Ltd | Wholesale & retail | 2012 |
| Amanda Cherrington Consulting Limited | Professional & scientific | 2024 |
| Amanda Longhurst Interiors Ltd | Professional & scientific | 2018 |
| Amandrm Ltd | Real estate | 2024 |
| Amazalign Ltd | Health & social care | 2011 |
| Amazilla Solutions Ltd | Professional & scientific | 2023 |
| Amazing Maurice 2 Productions Limited | Information & communication | 2024 |
| Amazing Space (Loft Conversions) Limited | Construction | 2005 |
| Amazing Space (South East) Limited | Professional & scientific | 2014 |
| Amazing Space Holding Company Limited | Professional & scientific | 2021 |
| AMB3 Limited | Professional & scientific | 2016 |
| Ambassador House Limited | Real estate | 2020 |
| Amberside Management Limited | Households | 2007 |
| Ambient 360 Limited | Construction | 2019 |
| Ambstal Consultancy Ltd | Extraterritorial | 2018 |
| Ambuild Limited | Extraterritorial | 2007 |
| Amcm Limited | Real estate | 2016 |
| Amdc Overseas Ltd | Administrative & support | 2020 |
| Amelia Avenue Limited | Real estate | 2024 |
| Amelia Zarych Bespoke Ltd. | Manufacturing | 2023 |
| AMG Translations Limited | Administrative & support | 2014 |
| Amit Patel Dentistry Ltd | Health & social care | 2010 |
| AMK Enterprises Limited | Real estate | 2005 |
| Amkom Investments Limited | Real estate | 2019 |
| AML First Ltd | Hospitality | 2026 |
| AML Payroll Services Limited | Administrative & support | 1996 |
| AML Payroll Services Sussex Limited | Administrative & support | 2003 |
| Ammaa Investments Limited | Real estate | 2025 |
| Amorphous Therapy Limited | Wholesale & retail | 2024 |
| Amos (Eastbourne) Limited | Administrative & support | 2015 |
| Amy's Childminding Limited | Health & social care | 2025 |
| Amyalexhastings Ltd | Hospitality | 2018 |
| AN & KI Limited | Real estate | 2020 |
| AN KA Beauty Ltd | Other services | 2013 |
| Anamak Ltd | Health & social care | 2019 |
| Ananya Digital Diagnostics Ltd | Health & social care | 2026 |
| Anatolia (Sussex) Limited | Hospitality | 2015 |
| Anay Investments Ltd | Health & social care | 2019 |
| Ancells Estates Limited | Real estate | 2002 |
| Anchor 8 Holding Ltd | Financial services | 2022 |
| Anchor House RTM Limited | Real estate | 2015 |
| Anchor Property & Lets Ltd | Wholesale & retail | 2025 |
| Anchorage Bioenergy LLP | | 2008 |
| Andcer Consulting Limited | Professional & scientific | 2024 |
| Anderida Adolescent Care Limited | Health & social care | 1992 |
| Anderida Bay Limited | Professional & scientific | 2006 |
| Anderida RTM Company Limited | Households | 2019 |
| Andm Ltd | Professional & scientific | 2024 |
| Andreimfa Ltd | Transport & logistics | 2025 |