| Additional Bookkeeping Company Limited | Professional & scientific | 2003 |
| Addmaple Ltd | Information & communication | 2022 |
| ADE Developments Limited | Administrative & support | 2016 |
| ADE DRN Ltd | Real estate | 2021 |
| ADE Global Ltd | Other services | 2024 |
| ADE Lets Ltd | Real estate | 2018 |
| Adelec Management Ltd | Financial services | 2021 |
| Adelman & Co. Ltd | Real estate | 2024 |
| Adelphi Support and Development Ltd | Professional & scientific | 2025 |
| Aden Pro-Form Holdings Limited | Manufacturing | 2021 |
| Aden Pro-Form Limited | Manufacturing | 1996 |
| Adenne Ventures Ltd | Real estate | 2025 |
| Adesgo Ltd | Health & social care | 2020 |
| Adgarmz Ltd | Wholesale & retail | 2025 |
| ADH Shipwright Limited | Manufacturing | 2001 |
| Adhd Professionals Limited | Health & social care | 2025 |
| Adhdspecialistclinicuk Ltd | Administrative & support | 2025 |
| Adjustable BED Repairs Ltd | Other services | 2025 |
| Adminnovate Ltd | Administrative & support | 2024 |
| Adnan Khanuk Ltd | Wholesale & retail | 2024 |
| Adnexus Limited | Professional & scientific | 2025 |
| Adorned by Alaafia Ltd | Wholesale & retail | 2024 |
| Adpro Ltd | Hospitality | 2008 |
| Adrentals Ltd | Real estate | 2022 |
| Adrian Speed Trans Limited | Transport & logistics | 2016 |
| Adriel Care Limited | Administrative & support | 2010 |
| Adriel Properties Ltd | Real estate | 2016 |
| ADS Executive Limited | Other services | 2023 |
| Adsroad Pass Limited | Information & communication | 2023 |
| Adsweb Investments Ltd. | Information & communication | 2017 |
| ADV13 Limited | Real estate | 2022 |
| Advance Shielding Solutions Ltd | Other services | 2018 |
| Advanced Assembly Solutions Ltd | Manufacturing | 2024 |
| Advanced Building Services (UK) Ltd | Construction | 2012 |
| Advanced Demolition (Southern) Limited | Construction | 2003 |
| Advanced In-Car Technologies Limited | Information & communication | 2005 |
| Advanced Orthodontics Limited | Health & social care | 2021 |
| Advanced Research Ltd | Professional & scientific | 2013 |
| Advanced-Assemblies Ltd | Information & communication | 2017 |
| Adventure Challenge Events Limited | Arts & recreation | 2005 |
| Adventure Pirate Ltd | Arts & recreation | 2017 |
| Adventure Sports Media Ltd | Information & communication | 2019 |
| Adventurous Artisans Ltd | Wholesale & retail | 2025 |
| Aegion Defence Labs Limited | Information & communication | 2025 |
| Aeipathy Limited | Manufacturing | 2017 |
| Aeonhouse Ltd | Wholesale & retail | 2025 |
| Aercomp Precision Engineering Limited | Professional & scientific | 1997 |
| Aerialwise (Dorset) Ltd | Other services | 2011 |
| Aerolith Limited | Other services | 2025 |
| Aeronautical & General Instruments Limited | Manufacturing | 1915 |
| Aeronautical & GI Holdings Limited | Professional & scientific | 2014 |
| Aerospace & Industrial Controls Limited | Extraterritorial | 2016 |
| Aerospace GSE Limited | Wholesale & retail | 2012 |
| Aerotech Precision Manufacturing Limited | Professional & scientific | 1996 |
| Aerothermal Technology Group Limited | Professional & scientific | 1978 |
| AET Transport Group Limited | Financial services | 2017 |
| AET Transport Properties Limited | Real estate | 2017 |
| Aetha Design Holdings Ltd | Financial services | 2022 |
| Aetha Design Studio Limited | Professional & scientific | 2018 |
| Aetherix Frontier Tech Ltd | Wholesale & retail | 2025 |
| Aetsam Ltd | Wholesale & retail | 2025 |
| Aevans Solutions Ltd | Wholesale & retail | 2024 |
| Affinity Care Limited | Extraterritorial | 2002 |
| Affinity Care Management Limited | Health & social care | 2007 |
| Affinity Emerson House Ltd | Health & social care | 2026 |
| Affinity EV Limited | Extraterritorial | 2025 |
| Affordable Property Solutions (Dorset) Limited | Real estate | 2006 |
| AFG Design Studio Ltd | Professional & scientific | 2023 |
| Afrak Nexgen Solution Ltd | Wholesale & retail | 2025 |
| African Compass Trading Ltd | Manufacturing | 2021 |
| African Developments Ltd | Construction | 2024 |
| African Entity Ltd | Wholesale & retail | 2021 |
| Africans Market Ltd | Wholesale & retail | 2025 |
| AFS Dorset Ltd | Public administration | 2026 |
| AFT Services Ltd | Arts & recreation | 2026 |
| After GLO (Dorset) Ltd | Other services | 2024 |
| After Work Ripping Ltd | Wholesale & retail | 2026 |
| AFX Mixing and Pumping Technologies Limited | Manufacturing | 2015 |
| AG Formwork Ltd | Construction | 2020 |
| AG Property & Developments Limited | Construction | 2026 |
| AG22 Holdings Limited | Real estate | 2022 |
| AG25 Holdings Limited | Real estate | 2025 |
| Agape Care Solutions Ltd | Health & social care | 2011 |
| Agecroft Apartments Management Company Ltd | Households | 2015 |
| Agency 13 Ltd | Information & communication | 2023 |
| Agency Paye Limited | Administrative & support | 2023 |
| Agents Unleashed Limited | Information & communication | 2019 |
| Aggara Limited | Wholesale & retail | 2025 |
| Aghaaaqib Ltd | Wholesale & retail | 2025 |
| Agile Catalyst Limited | Information & communication | 2010 |
| Agile O Group Ltd | Administrative & support | 2026 |
| AGL Properties (Dorset) Limited | Real estate | 2015 |
| Agnieszka Plawska Dietetyk Psychodietetyk Ltd | Other services | 2024 |
| Agoge Real Estate Limited | Construction | 2022 |
| AGS Commercial Limited | Professional & scientific | 2024 |
| Agse Global Services UK Ltd | Manufacturing | 2015 |
| Aguara Marine Limited | Manufacturing | 2022 |
| Agws Construction and Engineering Ltd | Construction | 2025 |
| AH (Bournemouth) Limited | Construction | 2022 |
| AH (North Dorset) Limited | Construction | 2019 |