| Acacia Property Management Limited | Real estate | 1998 |
| Acames Ltd | Construction | 2011 |
| Acorn Park Homes Management Ltd | Real estate | 2015 |
| Across Town Taxis Limited | Transport & logistics | 2022 |
| Acstats Limited | Information & communication | 2012 |
| Acton GAS Plumbing and Heating Limited | Construction | 2023 |
| Adam J King Limited | Transport & logistics | 2023 |
| Adara Fire Safety Consultancy Ltd | Public administration | 2025 |
| Addison & Byford Limited | Construction | 1977 |
| Adhesives Research PTE Ltd | Information & communication | 2025 |
| Admiral East Ltd | Manufacturing | 2012 |
| Adria Concessionaires Limited | Wholesale & retail | 1988 |
| Adrian House Residents Association Limited | Households | 1982 |
| ADV Carpentry Limited | Construction | 2006 |
| Advance Power Limited | Construction | 2021 |
| Advantay Limited | Wholesale & retail | 2003 |
| Adventure Bike Shop Limited | Wholesale & retail | 2019 |
| Aelpha Ltd | Information & communication | 2026 |
| Aerospace Media Services Ltd | Administrative & support | 2019 |
| AFC Sudbury Limited | Arts & recreation | 1951 |
| Affect Accountancy Limited | Professional & scientific | 2015 |
| Affect Group Limited | Professional & scientific | 2015 |
| Affect Interactive Ltd | Financial services | 2024 |
| Affect Interactive SPV2 Ltd | Information & communication | 2024 |
| Affect Interactive SPV3 Ltd | Information & communication | 2024 |
| Afrm Coaching Ltd | Education | 2023 |
| After Market Technologies Ltd | Information & communication | 2017 |
| Agenomicsphd Limited | Other services | 2024 |
| Agentwise Ltd | Information & communication | 2025 |
| AHO Limited | Hospitality | 2021 |
| AHO3 Limited | Hospitality | 2023 |
| AHS Landscapes Limited | Construction | 2017 |
| Aircraft Component Engineering Support Limited | Manufacturing | 2001 |
| Airsoft (GB) Limited | Arts & recreation | 2026 |
| AJB Stays Limited | Households | 2024 |
| AJC Property Services Limited | Professional & scientific | 2021 |
| AJR Transport Ltd | Transport & logistics | 2023 |
| AKA Energy Limited | Mining & quarrying | 2025 |
| AKH Roofing Limited | Construction | 2019 |
| Akita AC Limited | Construction | 2025 |
| Aktieselskabet MT Holding Limited | Financial services | 2019 |
| Alaz Ltd | Hospitality | 2025 |
| Albane Courtois Ltd | Arts & recreation | 2017 |
| Albion Business Services Suffolk Ltd | Real estate | 2018 |
| Albola Investments Limited | Professional & scientific | 2010 |
| Alchemy Aesthetics & Well-Being Limited | Other services | 2021 |
| Alchemy Trading Partners Ltd | Hospitality | 2012 |
| Alcove Filmed Entertainment Ltd | Information & communication | 2019 |
| Aldeburgh House Limited | Financial services | 2023 |
| Alder Family Properties Limited | Real estate | 2024 |
| Alderman Walk (Ipswich) Management Company Limited | Households | 2004 |
| Alex’Scourier Ltd | Transport & logistics | 2024 |
| Alfresco Hire Limited | Administrative & support | 2009 |
| Alison Macmillan Limited | Administrative & support | 2023 |
| ALL Clear UK Group Limited | Administrative & support | 2025 |
| ALL Year Biker (Sudbury) Ltd | Wholesale & retail | 2019 |
| Allan C. Gillibrand Ltd | Construction | 2005 |
| Alphabet Developments LLP | | 2010 |
| ALS Optical Services Ltd | Professional & scientific | 2025 |
| Altek Chemical Engineering (2000) Limited | Water & waste | 2000 |
| Alvita's Boutique Limited | Wholesale & retail | 2020 |
| Amadeus Consulting & Management UK Ltd | Professional & scientific | 2019 |
| Amastra Limited | Information & communication | 2009 |
| Amazonian Music Publishing Ltd. | Information & communication | 1995 |
| Amb.Hiperformance Ltd | Arts & recreation | 2026 |
| Amberstone (Clare) Limited | Construction | 2021 |
| Amberstone Comprop Limited | Real estate | 2021 |
| Amberstone Freehold Limited | Real estate | 2021 |
| Amberstone Holding Company Limited | Financial services | 2021 |
| Amberstone Resprop Limited | Real estate | 2021 |
| Amec Works Limited | Construction | 2020 |
| Amelie Distribution Ltd | Wholesale & retail | 2022 |
| Ammk Ltd | Financial services | 2010 |
| Amokh Ltd | Transport & logistics | 2015 |
| Amor Interior Design Ltd | Wholesale & retail | 2014 |
| Amor Property Ltd | Real estate | 2021 |
| Ampage Limited | Professional & scientific | 2025 |
| Ampmc Ltd | Construction | 2024 |
| AMS Advanced Medical Services Limited | Professional & scientific | 1999 |
| Ancestor Discovery Ltd | Other services | 2022 |
| Andrew Babicz Ltd. | Professional & scientific | 2014 |
| Andy Pinkus Limited | Construction | 2010 |
| Anglia Composites Limited | Administrative & support | 2007 |
| Anglia Court Maintenance Co Ltd | Real estate | 2013 |
| Anglia Pallet Racking Company Limited | Construction | 2009 |
| Anglia Print Solutions Limited | Wholesale & retail | 1977 |
| Anglia Rustguard Limited | Manufacturing | 1978 |
| Anglian PHE Limited | Construction | 2014 |
| Anglo GAS & Heating Services Limited | Construction | 2008 |
| Anglo Investments IPS Limited | Real estate | 2001 |
| Angus Taylor Studio Ltd | Professional & scientific | 2025 |
| Anima Games Ltd | Wholesale & retail | 2022 |
| Animus-Hr Limited | Administrative & support | 2003 |
| Annie’S Angels Ltd | Administrative & support | 2025 |
| Antec International Limited | Manufacturing | 1961 |
| ANTEP63 Ltd | Hospitality | 2025 |
| Antonia Brandes Consultancy Limited | Professional & scientific | 2018 |
| ANY Wheel Auto's Ltd | Wholesale & retail | 2025 |
| Apex Automotive Suffolk Ltd | Wholesale & retail | 2025 |
| APL Theatre Staffing Limited | Health & social care | 2015 |