| Alex Winter Software Ltd | Information & communication | 2026 |
| Alexander Thomas Limited | Real estate | 2022 |
| Alexandra Cleaning Company Limited | Extraterritorial | 1986 |
| Alexon Business Services Ltd | Administrative & support | 2025 |
| Alignment Studios Ltd | Health & social care | 2024 |
| Alison Craig Coaching Ltd. | Professional & scientific | 2013 |
| Alita Studios Limited | Wholesale & retail | 2024 |
| ALL About Packaging Limited | Administrative & support | 2018 |
| ALL About Polythene Limited | Extraterritorial | 2023 |
| ALL Done 4 YOU Limited | Wholesale & retail | 2006 |
| ALL Hands Together Ltd | Education | 2024 |
| ALL Haulage Limited | Transport & logistics | 2009 |
| ALL Seasons Aesthetics Ltd | Other services | 2021 |
| ALL Senses Limited | Hospitality | 2024 |
| ALL Square Accounting Services Ltd | Professional & scientific | 2020 |
| ALL Your GAS Plumbing & Electric Needs Ltd | Construction | 2022 |
| Allan E-Store Ltd | Wholesale & retail | 2025 |
| Allbrook Farm Management Limited | Households | 2013 |
| Alliance Roofing Group Limited | Construction | 2026 |
| Allied National Recycling Limited | Transport & logistics | 2014 |
| Allington Lane Ltd | Households | 2025 |
| Allio Ltd | Information & communication | 2024 |
| Allports Chauffeur Services Ltd | Transport & logistics | 2024 |
| Allround Plant Limited | Administrative & support | 1995 |
| Aloha World Travel Limited | Administrative & support | 2003 |
| Alpha Funding Solutions Ltd | Financial services | 2025 |
| Alpha IT UK Limited | Information & communication | 2004 |
| Alpha Plumbing and Heating Limited | Construction | 2007 |
| Alpha Scan Computers Limited | Information & communication | 1992 |
| Alphabeing Global Ltd | Hospitality | 2025 |
| Alresford Body Shop Limited | Wholesale & retail | 2025 |
| Alrt Fire & Security Ltd | Public administration | 2026 |
| ALS Contract Limited | Professional & scientific | 2017 |
| ALT Programme & Project Management Limited | Real estate | 2015 |
| ALT Property Management Limited | Real estate | 2025 |
| Altivorum Limited | Professional & scientific | 2026 |
| Alto Venture Ltd | Professional & scientific | 2024 |
| Alverstoke Pickleball Club Limited | Arts & recreation | 2025 |
| ALX Security Limited | Administrative & support | 2025 |
| AM Accounts Inc Ltd | Professional & scientific | 2026 |
| AMA Forklifts Limited | Transport & logistics | 2012 |
| Amanda L Ward Ltd | Administrative & support | 2022 |
| Amani Cuisine Limited | Hospitality | 2012 |
| Amar London Ltd | Health & social care | 2017 |
| Amber Propety Ltd | Real estate | 2024 |
| Amberleigh House (Curdridge) Limited | Construction | 2025 |
| Ambient Systems Limited | Information & communication | 2026 |
| Ambleglow Holdings Limited | Professional & scientific | 2008 |
| Ambleglow Limited | Professional & scientific | 1981 |
| Ambrose Technologies Ltd | Information & communication | 2019 |
| AMBROSE86 Ltd | Construction | 2017 |
| Amcall Communications Limited | Information & communication | 1998 |
| Amcoro Services Ltd | Construction | 2012 |
| AMD Programme Management Limited | Professional & scientific | 2016 |
| AME South Limited | Construction | 2016 |
| Amelia Nicholas Limited | Real estate | 2023 |
| American Golf Holidays Limited | Professional & scientific | 2002 |
| AMH Trading Limited | Other services | 2020 |
| Amigo Holdings (South) Ltd | Financial services | 2026 |
| Amigo Residential Ltd | Real estate | 2026 |
| Aminex Group Ltd | Construction | 2025 |
| Ammonite Ironwork Ltd | Manufacturing | 2021 |
| Amoena (UK) Limited | Wholesale & retail | 1988 |
| AMP TEC Electrical Engineering and Contracting Ltd | Construction | 2021 |
| Ampfield Traffic Consultants Ltd | Professional & scientific | 2011 |
| Amphoteric Analytical Limited | Professional & scientific | 2014 |
| Amritzing Solutions Ltd | Professional & scientific | 2025 |
| AMY Edwards Limited | Financial services | 2025 |
| ANA Vadillo Limited | Professional & scientific | 2013 |
| Anaa Limited | Wholesale & retail | 2017 |
| Andhold Ltd | Real estate | 2003 |
| Andrew Ballard and Co Limited | Construction | 2025 |
| Andrew Nicholson Limited | Health & social care | 2018 |
| Andrew Patterson Project Consultancy Ltd | Professional & scientific | 2025 |
| Andrews Automotive Engineering Ltd | Wholesale & retail | 2021 |
| Andy's Driving School Ltd | Education | 2020 |
| Angela Barr Accountancy Services Limited | Professional & scientific | 1996 |
| Angelic Relaxation Massage Ltd | Health & social care | 2021 |
| Anglo Vapour Ltd | Wholesale & retail | 2013 |
| ANJ Studios Ltd | Information & communication | 2026 |
| Anna Pinkerton Limited | Health & social care | 2015 |
| Anna Reynolds Creative Ltd | Administrative & support | 2019 |
| Anna Valentine Limited | Manufacturing | 2002 |
| Anthoney Investments Limited | Real estate | 2021 |
| Antos Garage Limited | Wholesale & retail | 2020 |
| Anzali Property Ltd | Real estate | 2020 |
| AO UK Limited | Administrative & support | 2005 |
| Ap-Co-Op Limited | Financial services | 2022 |
| Apeware Limited | Information & communication | 2012 |
| Apex Agency Online Ltd | Administrative & support | 2025 |
| Apex Carpentry and Renovations Ltd | Construction | 2026 |
| Apex Clinical Training Ltd | Education | 2026 |
| Apex Electrics Limited | Construction | 2011 |
| Apex Performance Clinic Limited | Health & social care | 2023 |
| Apex UAS Limited | Information & communication | 2026 |
| APM GEO Limited | Professional & scientific | 2013 |
| APN Digital Services Ltd | Wholesale & retail | 2024 |
| Appdev Consulting Limited | Other services | 2012 |
| Appearance UK Am-Pm Services Limited | Construction | 2014 |
| Apple Cars Ltd | Transport & logistics | 2025 |