| Alpha Electrical Contractors Southern Ltd | Construction | 2004 |
| Alpha Foxtrot Limited | Transport & logistics | 2025 |
| Alpha Omega Skincare Ltd | Other services | 2024 |
| Alpha Plumbing Services Ltd | Construction | 2026 |
| Alpha Retail Trading Ltd | Wholesale & retail | 2021 |
| Alphonsa Care Ltd | Health & social care | 2021 |
| Alpine Christmas Markets Limited | Wholesale & retail | 2017 |
| Alpine Property Management Ltd | Real estate | 2023 |
| Alpine Technica Ltd | Information & communication | 2022 |
| ALS Operations Ltd | Administrative & support | 2017 |
| ALS Ultrasonics Limited | Administrative & support | 1999 |
| Alsaab Ltd | Wholesale & retail | 2018 |
| ALT Property Solutions Ltd | Real estate | 2025 |
| ALT Rock Limited | Hospitality | 2024 |
| ALT.UN365 Limited | Other services | 2024 |
| Alternatives ST James LLP | | 2005 |
| Alteus Solutions Limited | Information & communication | 2016 |
| Altiori Freehold Limited | Real estate | 2023 |
| Altitude (Poole) Management Company Limited | Households | 2013 |
| Altitude 460 Limited | Professional & scientific | 2018 |
| Altitude Electrical Limited | Construction | 2023 |
| Alto Repair Limited | Construction | 2012 |
| Altola Limited | Financial services | 2025 |
| Alton Capital Group Limited | Financial services | 2023 |
| Alton Capital Limited Partnership | | 2018 |
| Alton Court Management Company Limited | Households | 2002 |
| Alton Lodge Management Co. Limited | Households | 1969 |
| Alum Chine Construction Limited | Administrative & support | 2003 |
| Alum Court (Bournemouth) Limited | Households | 2009 |
| Alum Heights Limited | Real estate | 2009 |
| Alum Media Limited | Information & communication | 2014 |
| Alumdale Court Ltd | Households | 2003 |
| Alumdale Limited | Construction | 1996 |
| Alumdale Properties Limited | Real estate | 2016 |
| Alumhurst Road Management Company Limited | Households | 2006 |
| Aluminium Door & Window Solutions Ltd | Manufacturing | 2012 |
| Aluminium Gutters Ltd | Extraterritorial | 2020 |
| Alverton Court Management Company Limited | Households | 1969 |
| Alverton Hall Freehold Limited | Real estate | 1999 |
| Alvin Bournemouth Ltd | Other services | 2014 |
| Alvista Torquay Limited | Information & communication | 2013 |
| Alvium Ltd | Manufacturing | 2025 |
| Always Taxis Limited | Transport & logistics | 2010 |
| Alzote Limited | Professional & scientific | 2022 |
| AM International Property and Investments Limited | Households | 2021 |
| AM Sky Capital Limited | Real estate | 2025 |
| AM7 Holding Ltd | Financial services | 2025 |
| AMA 12 Ltd | Health & social care | 2021 |
| AMA Partnership Ltd | Wholesale & retail | 2014 |
| Amaanie Limited | Wholesale & retail | 2026 |
| Amadea Limited | Information & communication | 2022 |
| Amadiz Care Ltd | Health & social care | 2014 |
| Amanda J Newell Limited | Health & social care | 2014 |
| Amani Property Services Limited | Administrative & support | 2011 |
| Amara Auto Vehicle Ltd | Transport & logistics | 2025 |
| Amari Court Limited | Households | 2005 |
| Amarluxurystays Ltd | Real estate | 2024 |
| Amaya SM Ltd | Financial services | 2022 |
| Amaya Solutions Limited | Information & communication | 2011 |
| Amaylia Limited | Manufacturing | 2023 |
| AMB Children's Social Care Consultancy Limited | Professional & scientific | 2024 |
| Ambien Ltd | Real estate | 2023 |
| Ambient Studios & Games Limited | Information & communication | 2026 |
| Ambienx Limited | Administrative & support | 2025 |
| Ambiglaze Ltd | Wholesale & retail | 2025 |
| Ambitious Education Ltd | Education | 2023 |
| Ambruch Ltd | Professional & scientific | 2025 |
| AMC Developements Limited | Construction | 2010 |
| AMC Management Solutions Limited | Professional & scientific | 2014 |
| AMC Pro Builders Ltd | Construction | 2022 |
| AMC Property Portfolio Ltd | Real estate | 2020 |
| Amco Heating Limited | Manufacturing | 2016 |
| AMD Property Developments Limited | Construction | 2007 |
| Amelia Groundworks Limited | Construction | 2015 |
| Amelitag Limited | Health & social care | 2022 |
| Amerc Ltd | Transport & logistics | 2024 |
| American Candy & Vape Limited | Wholesale & retail | 2023 |
| Ameriminds Solutions Ltd | Administrative & support | 2024 |
| Ameriscot Commercial a Limited | Real estate | 2015 |
| Ameriscot Commercial Limited | Real estate | 2006 |
| Amersham Court Freehold Limited | Hospitality | 2008 |
| AMF Holdings Limited | Agriculture & fishing | 2009 |
| AMH Plumbing Heating and Bathrooms Limited | Construction | 2009 |
| Amirez Limited | Professional & scientific | 2016 |
| AMJ Cars Services Ltd | Wholesale & retail | 2020 |
| AMJ ENG Limited | Professional & scientific | 2018 |
| AMJ Real Estate Developments Ltd | Construction | 2020 |
| Amjad ALI & Sons Ltd | Wholesale & retail | 2025 |
| AMK Properties Ltd | Real estate | 2004 |
| AML (Dorset) Ltd | Wholesale & retail | 2010 |
| Ammtek Limited | Information & communication | 2010 |
| Ammuttu & Co Ltd | Real estate | 2025 |
| Amnav Holdings Limited | Wholesale & retail | 2024 |
| Amoodi.Edu Ltd | Education | 2025 |
| Amore Sushi Limited | Hospitality | 2026 |
| Amped Electrical Dorset Limited | Construction | 2020 |
| Amphibian and Reptile Conservation Trust | Arts & recreation | 2009 |
| Amprenta Properties Ltd | Real estate | 2022 |
| AMR 87 Limited | Real estate | 2011 |
| AMR87 Property Ltd | Real estate | 2017 |