| Amex Consultancy Limited | Professional & scientific | 2023 |
| AMI Jukebox Company Limited | Wholesale & retail | 2018 |
| Ammohive Ltd | Wholesale & retail | 2023 |
| Ammys Store Ltd | Wholesale & retail | 2022 |
| Amni Beauty Limited | Other services | 2026 |
| Amor Consultancy 2 Limited | Administrative & support | 2026 |
| Amor Social Care Limited | Health & social care | 2019 |
| Ampersand Fragrances Ltd | Wholesale & retail | 2019 |
| AMW Telecoms Consulting Ltd | Information & communication | 2019 |
| AMZ Enterprises Ltd. | Health & social care | 2012 |
| Ananta Advisory Limited | Professional & scientific | 2024 |
| Ananta Infinity Limited | Professional & scientific | 2010 |
| Anarge Limited | Other services | 2013 |
| Anastasia Solution Ltd | Transport & logistics | 2015 |
| Anchol Ltd | Real estate | 2016 |
| Anchor Living Solutions Ltd | Real estate | 2026 |
| Anchorage Advisory Services Limited | Administrative & support | 2014 |
| Ancilla Metal Limited | Manufacturing | 2024 |
| AND Fire Compliance Ltd | Professional & scientific | 2026 |
| Anden Environmental Services Limited | Administrative & support | 2009 |
| Andiamo Pizzeria Ltd | Hospitality | 2025 |
| Andover Financial Solutions Limited | Professional & scientific | 2007 |
| Andreas 2006 Ltd | Construction | 2015 |
| Andrew Construction Recruitment Limited | Other services | 2011 |
| Andrews & Sons Limited | Real estate | 2013 |
| Andrews Property Oversight Limited | Households | 2026 |
| Andson Vertex Ltd | Wholesale & retail | 2025 |
| Anduril Limited | Information & communication | 2015 |
| Andy Drylining Ltd | Construction | 2024 |
| Andy Ramage Training Ltd | Arts & recreation | 2019 |
| Angel Alarms & Security Systems Limited | Administrative & support | 2013 |
| Anglia Properties Limited | Construction | 1983 |
| Angry Duck Limited | Real estate | 2025 |
| ANI Sport Limited | Arts & recreation | 2023 |
| Animal AID Festival Limited | Other services | 2022 |
| Animall Ltd | Extraterritorial | 2002 |
| Anissavi Private Limited | Real estate | 2024 |
| Anitan Care Limited | Health & social care | 2020 |
| Ankarol Atelier Ltd | Manufacturing | 2026 |
| Ankl Limited Partnership | | 1997 |
| ANM Floor & Wall Designs Ltd | Construction | 2018 |
| Annette Corbett Consulting Ltd | Information & communication | 2019 |
| Annie’S Style Loft Limited | Wholesale & retail | 2025 |
| Anomaly Consultancy Limited | Information & communication | 2008 |
| Anomaly Consultants Limited | Financial services | 2002 |
| Anstruther Ltd | Other services | 2020 |
| Anthony James D'Amato Limited | Professional & scientific | 2006 |
| Antony's Nail Ltd | Other services | 2026 |
| Antos Hair and Beauty Limited | Other services | 2025 |
| Anuvu Audio Holdings Limited | Transport & logistics | 2025 |
| Anzco Foods UK Limited | Wholesale & retail | 2000 |
| AOS Cooling & Heating Limited | Professional & scientific | 2014 |
| AP Chef - Kitchen Consultancy Ltd | Hospitality | 2023 |
| AP Drywall Limited | Financial services | 2010 |
| AP MD Construction Ltd | Construction | 2022 |
| AP Wiffen Properties Limited | Real estate | 2021 |
| Apater UK Limited | Professional & scientific | 2019 |
| APB Property Investments Ltd | Real estate | 2021 |
| Apca Capital Ltd | Professional & scientific | 2018 |
| APD Limited | Manufacturing | 1980 |
| Apec Plant Limited | Administrative & support | 1987 |
| Apex Accounting Recruitment Ltd | Administrative & support | 2026 |
| Apex Asset Limited | Financial services | 2023 |
| Apex Assignments Company Limited | Wholesale & retail | 2006 |
| Apex Heights Property Limited | Real estate | 2023 |
| Apex Sports Group Ltd | Arts & recreation | 2009 |
| Aphj Property Services Limited | Real estate | 2022 |
| Apicem Salutem Ltd | Professional & scientific | 2021 |
| APJ Lettings Limited | Real estate | 2016 |
| Aplc Limited | Professional & scientific | 2024 |
| Apollo ENT Limited | Information & communication | 2020 |
| Appening NOW Limited | Information & communication | 2012 |
| Apple Fencing and Landscaping Limited | Administrative & support | 2018 |
| Appledore Developments Limited | Construction | 1997 |
| Applejack Country Show Ltd | Administrative & support | 2026 |
| Applied Business Academy Limited | Education | 2013 |
| Approved Building Ltd | Real estate | 2011 |
| Approved Cars Essex Ltd | Wholesale & retail | 2019 |
| APT Collections International Ltd. | Administrative & support | 2016 |
| APT Collections Limited | Administrative & support | 2018 |
| Apta Services Ltd | Construction | 2023 |
| Aqsm Ltd | Other services | 2017 |
| Aqua Flare Dynamics Ltd | Construction | 2024 |
| Aqua GAS Essex Ltd | Construction | 2014 |
| Aqua Shore Marine Limited | Other services | 2018 |
| Aquaberry Swim School Ltd | Arts & recreation | 2026 |
| Aquaheat (Essex) Limited | Construction | 2022 |
| Aquarius (Brentwood) Limited | Real estate | 2005 |
| ARA Care Benfield Hall Limited | Health & social care | 2025 |
| Araba Consulting Limited | Other services | 2026 |
| Aracas Investments Ltd | Financial services | 2021 |
| ARB Cassidy Limited | Health & social care | 2021 |
| Arbor Care Tree Services (South East) Limited | Agriculture & fishing | 2008 |
| ARC Global Group Ltd | Real estate | 2026 |
| ARC Property Rentals Ltd | Real estate | 2024 |
| ARC Risk Limited | Professional & scientific | 2016 |
| ARC93 Ltd. | Professional & scientific | 2015 |
| Arch Consult Global Ltd | Construction | 2021 |
| Arch Property Estates Ltd | Real estate | 2019 |
| Archer Property Maintenance Ltd | Construction | 2018 |