| ASN Capital Project Alpha Ltd | Construction | 2010 |
| ASN Capital Project Beta Ltd | Construction | 2010 |
| ASN Capital Project Gamma Ltd | Construction | 2010 |
| ASN Capital Property Ltd | Real estate | 2026 |
| ASN Taxi Limited | Transport & logistics | 2023 |
| Asocan Ltd | Real estate | 2020 |
| Aspect Care Group Ltd | Health & social care | 2026 |
| Aspect Domiciliary Care Limited | Health & social care | 2008 |
| Aspectopen Property Management Limited | Households | 1998 |
| Aspirant Careers Ltd | Administrative & support | 2015 |
| Aspire Global Advisory Ltd | Information & communication | 2025 |
| Aspire Hotels Ltd | Hospitality | 2023 |
| Aspire Life Ltd | Arts & recreation | 2021 |
| Aspire Management Company Limited | Real estate | 2009 |
| Aspire Work Clothing Limited | Wholesale & retail | 2005 |
| Aspiretech Solutions Limited | Information & communication | 2024 |
| Aspiron Holdings Limited | Administrative & support | 2025 |
| Aspiron Search Limited | Administrative & support | 2021 |
| Aspiron Ventures Limited | Financial services | 2024 |
| Aspt Ltd | Real estate | 2015 |
| ASR Property Management Limited | Real estate | 2018 |
| Assembly Ltd. | Information & communication | 1999 |
| Assemblysoft Ltd. | Information & communication | 2009 |
| Assessment Inc Ltd | Health & social care | 2013 |
| Asset Building Management Ltd | Construction | 2020 |
| Associated Instruments Repairs Limited | Manufacturing | 1997 |
| Associated Parking Limited | Transport & logistics | 2010 |
| Association of UK Accountants CIC | Other services | 2014 |
| Assssa Limited | Professional & scientific | 2021 |
| Assured Portfolio Management Ltd | Real estate | 2021 |
| AST Roofing (Bournemouth) Limited | Construction | 2001 |
| Asta BIM Design Ltd | Information & communication | 2017 |
| Astech Environmental Services Limited | Other services | 2020 |
| Asteri Holdings Ltd | Real estate | 2023 |
| Asteri Investments LLP | | 2023 |
| Astex Security Services Ltd | Hospitality | 2024 |
| Astley House (Bournemouth) RTM Company Limited | Households | 2015 |
| Astley Whittle Limited | Extraterritorial | 1999 |
| Aston and Barton Ltd | Administrative & support | 2021 |
| Astoria Casino (Bournemouth) Limited | Professional & scientific | 1961 |
| Astra Home Services Ltd | Construction | 2019 |
| Astra Removals South UK Ltd | Transport & logistics | 2025 |
| Astral Business Services Ltd | Administrative & support | 2022 |
| Astute Limited | Information & communication | 1998 |
| Astute Marketing Services Limited | Professional & scientific | 2008 |
| AT & F Solutions Limited | Information & communication | 2000 |
| AT IT Analyst Limited | Administrative & support | 2015 |
| AT8 Scaffolding Ltd | Construction | 2025 |
| Atalar Trading Ltd | Hospitality | 2025 |
| Atanos Transpo Limited | Transport & logistics | 2022 |
| Atassi Aesthetics Ltd | Health & social care | 2024 |
| ATG RTM Company Limited | Extraterritorial | 2005 |
| Athelney Court Freehold Limited | Households | 2003 |
| Athena Mobility Limited | Wholesale & retail | 2015 |
| ATI (Automotive Transport Intelligence) Ltd | Wholesale & retail | 2024 |
| Atlantic Consultancy Ltd | Administrative & support | 2017 |
| Atlantic Enterprise U.K. Limited | Health & social care | 1992 |
| Atlantis GAS Ltd | Construction | 2023 |
| Atlantis Homes South Ltd | Real estate | 2021 |
| Atlantis Projects Ltd | Professional & scientific | 2022 |
| Atlas Force Ltd | Administrative & support | 2025 |
| Atlas Group Investments Ltd | Real estate | 2025 |
| Atlas Portfolio Limited | Real estate | 2025 |
| Atlas Wings Engineering Ltd | Professional & scientific | 2026 |
| Atna Group Ltd | Administrative & support | 2025 |
| Atom Solutions Ltd | Administrative & support | 2006 |
| ATR SERVICES1 Ltd | Construction | 2019 |
| Atrium Imaging Limited | Health & social care | 2011 |
| Atsow Holdings Limited | Real estate | 2025 |
| Attain-It Ltd | Information & communication | 2013 |
| Attenborough Property Holdings Ltd | Real estate | 2025 |
| Attentive Care Solutions Ltd | Health & social care | 2025 |
| Attico Group Limited | Wholesale & retail | 2015 |
| Attrox Group Limited | Professional & scientific | 2023 |
| Aubritex Limited | Water & waste | 2020 |
| Aubs Construction Ltd | Construction | 2024 |
| Auburn Mansions (Branksome Park Poole) Flat Management Limited | Households | 1977 |
| Aubyn Electrical Services Limited | Professional & scientific | 2019 |
| Audiblaze Ltd | Professional & scientific | 2026 |
| Audio Feed Ltd | Arts & recreation | 2003 |
| Audio Investments Limited | Real estate | 2019 |
| Audio Sphera Ltd | Wholesale & retail | 2025 |
| Audio Take Limited | Information & communication | 2012 |
| Auditdapps Ltd | Administrative & support | 2025 |
| Audrey Manor Residents Limited | Households | 2019 |
| Auger Collective CIC | Arts & recreation | 2024 |
| Aura Brew Co. Ltd | Wholesale & retail | 2021 |
| Aura Nicolae Ltd | Wholesale & retail | 2011 |
| Aura Vayu Ltd | Energy | 2025 |
| Aurelius Bloodstock LLP | | 2022 |
| Aurelius Technical Services Ltd | Information & communication | 2013 |
| Aurelius Training Ltd | Administrative & support | 2019 |
| Aurex Plan Ltd | Construction | 2026 |
| Auric Global Ltd | Water & waste | 2019 |
| Aurora Gold Resources Limited | Mining & quarrying | 2025 |
| Aurora Heights Hotels Ltd | Hospitality | 2024 |
| Aurora Properties (Bournemouth) Ltd | Real estate | 2020 |
| Aurora Recovery Services Ltd | Transport & logistics | 2026 |
| Austin& White Support Group Limited | Health & social care | 2025 |
| Austins Climate & Gasworks Ltd | Construction | 2015 |