| Amory Developments (ELY) Limited | Construction | 1983 |
| Ampp Services Limited | Professional & scientific | 2007 |
| Andrew and JO Pearson Trading AS Drayman's SON Ltd | Hospitality | 2015 |
| Andrew Bland Carpentry Limited | Construction | 2003 |
| Andrew Court Residents Association Limited | Real estate | 1987 |
| Andrew Fleet Limited | Professional & scientific | 2005 |
| Andrew Martin Photography Limited | Professional & scientific | 2003 |
| Andrew Richards Limited | Wholesale & retail | 1997 |
| Andy Archer Consulting Limited | Other services | 2023 |
| Angel Aesthetics Limited | Administrative & support | 2017 |
| Angelic Brands LLP | | 2010 |
| Angell Inc London Ltd | Manufacturing | 2026 |
| Anglia Instruments Limited | Wholesale & retail | 1998 |
| Anglia Profiles Limited | Construction | 2014 |
| Anglia Security Services Limited | Administrative & support | 1997 |
| Anglia Tax & Accounting Ltd | Professional & scientific | 2025 |
| Anglia VS Ltd | Other services | 2018 |
| Anglian Accounting Support Ltd | Professional & scientific | 2011 |
| Anglodan Properties Ltd | Real estate | 2014 |
| Angry MAN Pictures Limited | Information & communication | 2002 |
| Anibel's Bridal Boutique Ltd | Wholesale & retail | 2023 |
| Animal Care in Egypt Limited | Professional & scientific | 1999 |
| Anna Kennerley Limited | Professional & scientific | 2019 |
| Anna Smith at David LEE Ltd | Real estate | 2020 |
| Antep Barber Ltd | Other services | 2024 |
| Anthony Barnes Coaching Ltd | Education | 2026 |
| Apex REG Ltd | Professional & scientific | 2016 |
| Apex Trader Software Limited | Information & communication | 2015 |
| APG Fitness (East Anglia) Limited | Arts & recreation | 2024 |
| Appletrees Houses Ltd | Real estate | 2023 |
| Appletrees Plumbing & Heating Ltd | Construction | 2014 |
| Aquoprotein Ltd | Agriculture & fishing | 2020 |
| ARC Climate Solutions Ltd | Construction | 2025 |
| Archer & Gaher Adventures Ltd | Administrative & support | 2018 |
| Archifarmlab Limited | Agriculture & fishing | 2014 |
| Arfox Ltd | Education | 2018 |
| Argenta Tree Surveys Limited | Professional & scientific | 2017 |
| Argo Mobile Repair Team Limited | Manufacturing | 2019 |
| Arise Business Limited | Real estate | 2024 |
| Aristo Pharma Limited | Professional & scientific | 2014 |
| Ariya & Arin Food Ltd | Hospitality | 2017 |
| ARK Empire Ltd | Administrative & support | 2021 |
| ARK Security Ltd | Administrative & support | 2020 |
| ARK Storage Limited | Administrative & support | 2013 |
| Arkümu Limited | Administrative & support | 2019 |
| Armiger Estates Limited | Extraterritorial | 2020 |
| Armourstore Limited | Other services | 2006 |
| Armourstore Self Storage Ltd | Other services | 2010 |
| Aroma Cafe Soham Limited | Hospitality | 2022 |
| Aroy D Thai Ltd | Hospitality | 2020 |
| Art Production London Ltd | Information & communication | 2020 |
| Art Unequalled Ltd | Wholesale & retail | 2018 |
| Artful EYE Ltd | Wholesale & retail | 2026 |
| Artworld Worldwide Ltd | Wholesale & retail | 2025 |
| Arumchan Korea Taekwondo Ltd | Education | 2026 |
| Arvis Group Limited | Education | 2016 |
| ARW Accountants Limited | Professional & scientific | 2019 |
| AS in Boat Limited | Professional & scientific | 2011 |
| ASA King Painter & Decorator Limited | Construction | 2012 |
| Ashco Building and Maintenance Services Limited | Construction | 2013 |
| Ashwild Community Wellness CIC | Health & social care | 2026 |
| Ashwood Bond Developments Ltd | Construction | 2019 |
| Asko Ltd | Hospitality | 2022 |
| Aspire Adaptations Ltd | Construction | 2020 |
| Aspire Holdings (Cambs) Ltd | Financial services | 2024 |
| Aspire Plumbing and Heating (Cambridgeshire) Ltd | Construction | 2012 |
| Assenti Estates Limited | Real estate | 2024 |
| Assenti Health Ltd | Professional & scientific | 2022 |
| Assist Aviation Limited | Administrative & support | 2011 |
| Assurebiz Ltd | Professional & scientific | 2020 |
| Assured Safety Limited | Professional & scientific | 2010 |
| Astonowners.Com Ltd | Other services | 2022 |
| Astromune Therapeutics Ltd | Professional & scientific | 2026 |
| Asynt Limited | Manufacturing | 2004 |
| Atack Whyte Knight Enterprises (Awke) LLP | | 2011 |
| Atlas Gardens Maintenance Limited | Administrative & support | 2017 |
| Atom Technologies Limited | Construction | 2003 |
| Atrium Holdings Limited | Professional & scientific | 2008 |
| Attleborough AD Plant Limited | Energy | 2018 |
| Attleborough Eco Electric Limited | Energy | 2004 |
| Audiological Specialist Care Ltd | Health & social care | 2016 |
| Audley Garage (Littleport) Limited | Professional & scientific | 1959 |
| Audrey Court Management Company Limited | Real estate | 1988 |
| Audus Carpentry Ltd. | Construction | 1997 |
| Aujla (ELY) Limited | Transport & logistics | 2016 |
| Aureus Solidus Limited | Wholesale & retail | 2026 |
| Aurum Capital LP | | 2024 |
| Australia Court Garages Ltd | Households | 2021 |
| Australia Court Limited | Households | 2000 |
| Author Choices Limited | Information & communication | 2017 |
| Author Publishers Ltd | Information & communication | 2020 |
| Auto Recovery Ltd | Wholesale & retail | 2023 |
| Automated Welding Products Ltd | Professional & scientific | 2014 |
| AV Building (East Anglia) Limited | Construction | 2014 |
| Aven Finance Group Ltd | Financial services | 2026 |
| Averlon P.H.S Ltd | Construction | 2018 |
| Avid Language Limited | Information & communication | 2019 |
| Avocet Electrical Technology Limited | Construction | 2017 |
| Avocet Staffing Limited | Hospitality | 2019 |
| Avontus Software Ltd | Information & communication | 2015 |