| Alphin SPV Limited | Construction | 2018 |
| Alps Plumbing and Heating Ltd | Construction | 2025 |
| Alterstart UK Ltd | Wholesale & retail | 2019 |
| Altier Tech Ltd | Professional & scientific | 2023 |
| Altitude Medical Limited | Health & social care | 2019 |
| Always Cleansing Limited | Households | 2001 |
| Amadeus Shellfish Company Limited | Agriculture & fishing | 2003 |
| Amanda Pickering Operations Limited | Administrative & support | 2022 |
| Amarena Care Ltd | Health & social care | 2026 |
| Amasus Short-Sea Ltd | Financial services | 2013 |
| Ambc Building Contractors Ltd | Construction | 2020 |
| Amberley Gardens Residents Limited | Households | 2022 |
| Amberley Services Limited | Information & communication | 2008 |
| Amberslane Cleaning Ltd | Administrative & support | 2025 |
| Ambessue Ltd | Hospitality | 2021 |
| Amela (SW) Ltd | Hospitality | 2025 |
| Amelia Daniels Ltd | Extraterritorial | 2019 |
| American Nails 2 Ltd | Other services | 2025 |
| Amino Co. Ltd | Wholesale & retail | 2026 |
| Amity Veterinary Care Ltd | Professional & scientific | 2020 |
| AML Windows & Doors Ltd | Construction | 2019 |
| Ammon Enterprises Limited | Wholesale & retail | 2010 |
| Ampology Limited | Information & communication | 2016 |
| AMS Technologies Limited | Wholesale & retail | 1989 |
| Amtech Premium Limited | Wholesale & retail | 2019 |
| Amtek Plastics UK Limited | Manufacturing | 2015 |
| Amtj Retail Ltd | Wholesale & retail | 2025 |
| Amulet Hotkey Ltd | Manufacturing | 1990 |
| AMY Creates Ltd | Professional & scientific | 2025 |
| Anasarai Limited | Public administration | 2024 |
| Anchor Property & Lettings Ltd | Real estate | 2024 |
| Anderson Air Conditioning Ltd | Construction | 2023 |
| Andrade Coleman Ltd | Hospitality | 2025 |
| Andrew Hill Salon Limited | Professional & scientific | 2002 |
| Angel Oak Carpentry Limited | Construction | 2021 |
| Angelion Limited | Professional & scientific | 2015 |
| Anglo Removals Limited | Transport & logistics | 2023 |
| Anglowide Consultants Limited | Information & communication | 1996 |
| Animals in Distress (Torbay and Westcountry) | Agriculture & fishing | 2004 |
| Anna Fisher Beauty Ltd | Other services | 2019 |
| ANP Bricklaying and Construction Ltd | Construction | 2025 |
| Ansum Kitchen Ltd | Hospitality | 2020 |
| Antony Fitton Limited | Health & social care | 2013 |
| AP Building Services (SW) Limited | Construction | 2014 |
| AP Holdings (SW) Ltd | Real estate | 2025 |
| Ap&S Leasing Limited | Transport & logistics | 2003 |
| Apcn Limited | Administrative & support | 2021 |
| APE Vodka Ltd | Wholesale & retail | 2026 |
| Aperturetech Ltd | Information & communication | 2024 |
| Apex Decking Ltd | Manufacturing | 2026 |
| Apex Management Consultants Limited | Professional & scientific | 1997 |
| Aphero Carbon Ltd | Wholesale & retail | 2025 |
| Aphero Wheels Ltd | Wholesale & retail | 2025 |
| Apollo Services and Cleansmiths Ltd | Manufacturing | 2000 |
| Appian Logistics Ltd | Transport & logistics | 2020 |
| Applegarth 1965 Limited | Extraterritorial | 2014 |
| Appletree Housing & Property Services Ltd | Real estate | 2025 |
| APS (Ashburton) Ltd | Real estate | 2002 |
| Apse Group Ltd | Professional & scientific | 2023 |
| APX Drone Services Ltd | Professional & scientific | 2022 |
| Aqua-Tech Consultancy Ltd | Professional & scientific | 2009 |
| Aquatics South West (Holdings) Limited | Financial services | 2025 |
| Aquifer Water Filtration Ltd | Water & waste | 2024 |
| Arbitrage Business Solutions Limited | Professional & scientific | 2015 |
| Arbitrium NOW Ltd | Professional & scientific | 2019 |
| ARC Steel Projects Limited | Manufacturing | 2000 |
| Arccas (Midlands) Limited | Administrative & support | 2011 |
| Arccas (South West) Ltd | Construction | 2020 |
| Arch Brook Engineering Ltd | Professional & scientific | 2025 |
| Archimetrics Ltd | Professional & scientific | 2011 |
| Arcus Altor Limited | Professional & scientific | 2010 |
| Ardent Construction Consultants Ltd | Professional & scientific | 2024 |
| ARE Friends Electric? Limited | Information & communication | 2023 |
| Area Managements (London) Limited | Construction | 1965 |
| Areon Digital Ltd | Information & communication | 2026 |
| Arete 101 Ltd | Real estate | 2023 |
| ARF Transport Ltd | Transport & logistics | 2016 |
| Argun Limited | Professional & scientific | 1998 |
| Ariamathea Ltd | Arts & recreation | 2016 |
| ARK in the Park Day Nursery Limited | Health & social care | 2002 |
| ARK Kitchens & Bathrooms Limited | Construction | 2003 |
| Arlo Solutions South West Limited | Administrative & support | 2021 |
| Arlo Solutions SW Limited | Construction | 2021 |
| Arlo SW Holdings Limited | Financial services | 2024 |
| Armada Land Ltd | Construction | 2026 |
| Armand Digital Limited | Wholesale & retail | 2020 |
| Aroma Newton Ltd | Hospitality | 2023 |
| Arrival Group Ltd | Arts & recreation | 2022 |
| Arrora Ltd | Water & waste | 2023 |
| Artary Limited | Arts & recreation | 2013 |
| Artfull Life CIC | Education | 2025 |
| Arthur's Deli Cafe Ltd | Hospitality | 2018 |
| Artisan Luxury Flooring Limited | Wholesale & retail | 2022 |
| Artistic Licence Engineering Limited | Manufacturing | 1988 |
| Artware Limited | Administrative & support | 2005 |
| Artworking Limited | Professional & scientific | 1998 |
| AS Above Ltd | Wholesale & retail | 2020 |
| ASH Futures Limited | Professional & scientific | 2011 |
| Ashburton Chefs Academy Limited | Education | 2016 |
| Ashburton Cookery School Limited | Education | 2006 |