| Alpha Financial Consultants (Somerset) Ltd | Financial services | 2006 |
| Alpha Health Limited | Extraterritorial | 2006 |
| Alpha Housing Services Limited | Real estate | 1988 |
| Alphaplus (Training and Translations) Limited | Professional & scientific | 1993 |
| Alpine Rope Access Ltd | Construction | 2026 |
| Alpinspur Properties Limited | Real estate | 1972 |
| Alro Publishing Limited | Information & communication | 2004 |
| Altenergy Community Investments Limited | Construction | 2023 |
| Altenergy Group Limited | Financial services | 2023 |
| Altenergy Limited | Construction | 2021 |
| Alteo Property Group Ltd | Real estate | 2026 |
| Alternative Blueprint Limited | Information & communication | 2008 |
| Alunadh Practice Ltd | Health & social care | 2025 |
| Alunafae Ltd | Manufacturing | 2024 |
| Alvington Place (Yeovil) Management Company Limited | Households | 2009 |
| ALX Lift Services Ltd | Professional & scientific | 2026 |
| AMA Livened Healthcare Ltd | Health & social care | 2026 |
| AMA1839 Ltd | Wholesale & retail | 2026 |
| Amal Healthcare Limited | Health & social care | 2021 |
| Amalia B Limited | Health & social care | 2019 |
| Amanda Galea Consulting Ltd | Professional & scientific | 2023 |
| Amas Services Limited | Health & social care | 2024 |
| Ambassadors International Limited | Wholesale & retail | 2007 |
| Amber Property Services Limited | Real estate | 2025 |
| Amber Rose Healthcare Ltd | Health & social care | 2022 |
| Ambernova Limited | Professional & scientific | 2024 |
| Ambertone Health and Beauty Limited | Other services | 2012 |
| Ambro Finance Limited | Financial services | 2012 |
| Ambrose & Locke Limited | Construction | 2013 |
| Ambrose Spence Consulting Ltd | Energy | 2022 |
| AMC (South West) Limited | Other services | 2018 |
| Amdex Analytics Ltd | Information & communication | 2019 |
| American Nails Taunton Ltd | Other services | 2018 |
| Amery Hospitality Limited | Hospitality | 2019 |
| Amica Care (Plymouth) Ltd | Health & social care | 2023 |
| Amica Care Trust | Health & social care | 2000 |
| Amiga Properties Limited | Real estate | 2006 |
| Amingford Grange (Trull) Management Company Limited | Real estate | 2014 |
| Amorlore Training & Development Ltd | Health & social care | 2025 |
| Amory Consulting Limited | Information & communication | 2018 |
| AMP Teamdream Ltd | Construction | 2020 |
| Amph Contracting Ltd | Manufacturing | 2025 |
| Amphenol Thermometrics (UK) Limited | Manufacturing | 1988 |
| AMS Media & Publishing Ltd | Administrative & support | 2014 |
| Ams-Sensors Ltd | Manufacturing | 2025 |
| Amshi Limited | Financial services | 2025 |
| AMT1 Holdings Ltd | Real estate | 2019 |
| AMT2 Investment Ltd | Real estate | 2022 |
| Amti Solutions Ltd | Professional & scientific | 2015 |
| Analysis International Limited | Public administration | 2011 |
| Analysis International Two Limited | Professional & scientific | 2014 |
| Analytics With Andrew Limited | Information & communication | 2023 |
| Anchors UP Ltd | Wholesale & retail | 2024 |
| Andrea Guest Residentials Limited | Health & social care | 2013 |
| Andreas Smyrniotis Ltd | Hospitality | 2026 |
| Andrew Coates Coaching and Consultancy Limited | Professional & scientific | 2020 |
| Andrew Green Building Contractor Limited | Construction | 2003 |
| Andrew Wackett Associates Ltd | Professional & scientific | 2003 |
| Andrews Ecology Limited | Professional & scientific | 2003 |
| Andy Care and Counselling Limited | Public administration | 2025 |
| Andy Foster's Haulage Limited | Wholesale & retail | 2010 |
| Andy Richards Limited | Information & communication | 2022 |
| Andy Uk/Eu Transport Ltd | Transport & logistics | 2019 |
| Andy's Web Kitchen Ltd | Information & communication | 2020 |
| Anees Diagnostics Ltd | Health & social care | 2025 |
| Angela Langford Limited | Manufacturing | 2012 |
| Angela Simmonds ODP Ltd | Health & social care | 2022 |
| Angela Smith HR Limited | Administrative & support | 2021 |
| Angels (Stratton House) Ltd | Health & social care | 2007 |
| Angry Dragon Investments Ltd | Financial services | 2022 |
| Anmiluan Ltd | Wholesale & retail | 2019 |
| Anna Edwards Sport Horses Limited | Arts & recreation | 2010 |
| Anna's Catering BC Ltd | Hospitality | 2024 |
| Annie and Lolo Ltd | Wholesale & retail | 2018 |
| Anodising Supplies Ltd | Manufacturing | 2025 |
| Ansador Limited | Administrative & support | 1982 |
| Ansric Limited | Professional & scientific | 2025 |
| Anstis Surveying Limited | Professional & scientific | 2017 |
| Antho IT Ltd | Information & communication | 2025 |
| Anthony Branfield Commercial Limited | Real estate | 2016 |
| Anthony Branfield Construction Limited | Construction | 2023 |
| Anthony Branfield Limited | Financial services | 2023 |
| Anthony Smith & Co (Pinksalt) Ltd | Professional & scientific | 2024 |
| Anthony Smith & Co. Limited | Professional & scientific | 2010 |
| AOL Mediplex Company Limited | Wholesale & retail | 2020 |
| AP Construction and Partners Ltd | Construction | 2016 |
| Apache Carpentry Limited | Manufacturing | 2021 |
| APD Vehicle Services Ltd | Wholesale & retail | 2017 |
| Apex Business Improvements Ltd | Information & communication | 2009 |
| Apex Evolution Ltd | Wholesale & retail | 2018 |
| Apex Funding Limited | Financial services | 2025 |
| Apexpro Development Limited | Real estate | 2024 |
| Aplins Farms Limited | Agriculture & fishing | 2020 |
| Aplins Practical Services Limited | Wholesale & retail | 2015 |
| Apogee Ltd | Real estate | 2024 |
| Apollo Property Company Gloucester Limited | Real estate | 2018 |
| Apollo Taunton Limited | Other services | 2025 |
| Apolloiq Ltd | Information & communication | 2023 |
| Apple Business Centre (Property Management) Limited | Households | 1992 |
| Apple County Cycles Limited | Wholesale & retail | 2023 |