| Andy Bishop Commissioning Limited | Construction | 2014 |
| Andy Windscreens Ltd | Administrative & support | 2015 |
| Angie's Hair and Beauty Limited | Other services | 2016 |
| Anglia Maintenance and Construction Limited | Construction | 2005 |
| Anglian Blasting Ltd | Construction | 2010 |
| Anglian Electrical Services Limited | Construction | 2015 |
| Anglian Rewinds Limited | Manufacturing | 1998 |
| Angos Food Ltd | Hospitality | 2025 |
| Animo Holding Company Limited | Administrative & support | 2020 |
| Animo Management Limited | Financial services | 2003 |
| Animo Payroll Services Ltd | Administrative & support | 2016 |
| Anna's Artisan Oven Ltd | Manufacturing | 2026 |
| Annabell Construction Ltd | Construction | 2023 |
| Anne Child Consultancy Ltd | Professional & scientific | 2026 |
| Anorma Ltd | Hospitality | 2013 |
| ANS Print Services Ltd | Manufacturing | 2004 |
| Antarian Solutions Limited | Wholesale & retail | 2013 |
| Antellas Developments Ltd | Construction | 2010 |
| Anthony Charles Estates Ltd | Real estate | 2025 |
| Anthony-James Fashion. Ltd | Wholesale & retail | 2020 |
| ANY Little Thing Ltd | Health & social care | 2016 |
| APA Trades Ltd | Wholesale & retail | 2023 |
| APD Supplies Ltd | Wholesale & retail | 2020 |
| Apex Construction Consultants Limited | Construction | 2024 |
| Apex Recruitment Services Limited | Administrative & support | 2025 |
| Apex Refinishing Ltd | Manufacturing | 2024 |
| Apollo Access Services Ltd | Information & communication | 2022 |
| Applewood Properties LLP | | 2019 |
| Aquabelle Swim School Limited | Arts & recreation | 2016 |
| Aquabloom Wellness Limited | Other services | 2025 |
| Aquatech Heating & Plumbing Limited | Construction | 2001 |
| Aquatrac (UK) Limited | Other services | 1992 |
| Aqutron Technology Limited | Information & communication | 2014 |
| Arad Safety Systems Limited | Construction | 2016 |
| Aran Pubs Limited | Hospitality | 2024 |
| Aras 68 Limited | Hospitality | 2019 |
| Aravis Recruitment Limited | Administrative & support | 2014 |
| Archies House Ltd | Hospitality | 2025 |
| Architectural Hub Limited | Professional & scientific | 2013 |
| Ardant Group Ltd | Construction | 2024 |
| Ardleigh Homes Ltd | Real estate | 2019 |
| Ardleigh Support Services Ltd | Wholesale & retail | 1996 |
| Aria Healthcare Services Ltd | Health & social care | 2025 |
| Arkham Hardware Ltd | Wholesale & retail | 2023 |
| Arme Consulting Ltd | Professional & scientific | 2020 |
| Armstrong Knight Executive Search Ltd | Administrative & support | 2014 |
| Arthurton Coachworks Limited | Wholesale & retail | 2018 |
| Artic Partners LLP | | 2014 |
| Artisan People 36T Ltd | Administrative & support | 2021 |
| Artisan People Aunties Ltd | Administrative & support | 2020 |
| Artisan People Group Ltd | Administrative & support | 2017 |
| Artmalta Gallery | | 2009 |
| Artsncrafty Limited | Wholesale & retail | 2025 |
| AS Luxfloor Ltd | Wholesale & retail | 2021 |
| Asbestos Surveys & Advisory Services Limited | Construction | 2004 |
| Asbigazzitgets Ltd | Arts & recreation | 2025 |
| Ascendia Education and Advisory Limited | Education | 2026 |
| Ashidam Medical Services Ltd | Health & social care | 2026 |
| Ashleigh Construction Limited | Construction | 1998 |
| Ashore Investments Limited | Wholesale & retail | 2026 |
| ASK PA Ltd | Health & social care | 2021 |
| Aspen Home Improvements (UK) Limited | Construction | 2008 |
| Aspen Home Improvements Ltd | Extraterritorial | 2011 |
| Aspgate Ltd | Information & communication | 2019 |
| Aspire Automotive Limited | Wholesale & retail | 2014 |
| Asrem Limited | Construction | 2023 |
| Assertive Assets Limited | Hospitality | 2018 |
| Associate Trainers Limited | Other services | 2014 |
| Astrum Search Limited | Administrative & support | 2021 |
| Ataray Ltd | Hospitality | 2018 |
| Atdt Limited | Education | 2000 |
| Atkins & Sons Home Improvements Ltd | Construction | 2025 |
| Atlas Home Solutions Limited | Wholesale & retail | 2005 |
| ATM Bar and Restaurants Ltd | Hospitality | 2023 |
| Atrix Services Limited | Extraterritorial | 2009 |
| Aulive Investments Ltd | Real estate | 2025 |
| Aulive Ltd | Administrative & support | 2022 |
| Aura Beauty Limited | Other services | 2015 |
| Aurald Synergy Health Ltd | Health & social care | 2025 |
| Auraya Limited | Administrative & support | 2009 |
| Austin Investment Properties Ltd | Real estate | 2022 |
| Austino-Uk Ltd | Construction | 2017 |
| Authentic Apparel Krew Ltd | Wholesale & retail | 2025 |
| Authentic Property Management Ltd | Financial services | 2018 |
| Auto Feeders (UK) Limited | Manufacturing | 2014 |
| Autopart (Wheel & Tyre) Ltd. | Wholesale & retail | 2001 |
| Avala Salon Studios Limited | Real estate | 2019 |
| Avalon Water Ltd | Wholesale & retail | 2024 |
| Avaunt (South East) Limited | Construction | 2013 |
| Avaunt Limited | Real estate | 2007 |
| AVD Holdings Limited | Financial services | 2018 |
| Avenue Neatspace Ltd | Construction | 2025 |
| Avis Accommodation Limited | Real estate | 2024 |
| Avis Property Investments Ltd | Financial services | 2023 |
| Avis Sourcing Limited | Administrative & support | 2024 |
| Avtronics Limited | Wholesale & retail | 2014 |
| Awells Services Ltd | Construction | 2026 |
| AWH Entertainment Ltd | Professional & scientific | 2024 |
| AXE Rims Ltd | Wholesale & retail | 2023 |
| Axiseng Ltd | Professional & scientific | 2024 |