| AKT Service Ltd | Wholesale & retail | 2019 |
| AL Hassan Developments Ltd | Real estate | 2026 |
| AL Zamool Technical Services Ltd | Real estate | 2023 |
| Alan Prescott Heating Company Limited | Real estate | 1974 |
| Alayo Property Ltd | Households | 2023 |
| ALAYOGOLDUK1 Ltd | Wholesale & retail | 2022 |
| Aldridge Furnishings Limited | Manufacturing | 2002 |
| Alexander-Hough Removals Limited | Transport & logistics | 2016 |
| Alexandru Florin Mustafa Ltd | Wholesale & retail | 2026 |
| Alexican Ltd | Manufacturing | 1996 |
| Alfresco Styles Ltd | Wholesale & retail | 2024 |
| Aliza Noor Ltd | Hospitality | 2025 |
| ALL 4 Pets Limited | Arts & recreation | 2003 |
| ALL Seasons Sales (UK) Limited | Other services | 2001 |
| Alliance Builders Ltd | Information & communication | 2019 |
| Allied Infrastructure Management Limited | Construction | 1994 |
| Allied Ventures Group Limited | Transport & logistics | 2026 |
| Allison Sumner Chartered Physiotherapist Ltd | Health & social care | 2002 |
| Ally Property Ltd | Real estate | 2022 |
| Alpha Keysafe Services Ltd | Information & communication | 2025 |
| Alpha News Limited | Wholesale & retail | 2022 |
| Alpha Roofing Systems Ltd | Construction | 2009 |
| Alpha Status Group Ltd | Wholesale & retail | 2020 |
| Alphaai Solutions Ltd | Information & communication | 2024 |
| Alston Services Limited | Education | 2023 |
| Aluminium Access Products Limited | Manufacturing | 2002 |
| AM Byth Global Ltd. | Professional & scientific | 2014 |
| Amazon Aquatic Wholesale Limited | Wholesale & retail | 2005 |
| AMG Bulding 365 Ltd | Construction | 2025 |
| Amigos Pro Detailing Ltd | Administrative & support | 2023 |
| Amnq Limited | Other services | 2017 |
| AMO Special Cables Limited | Manufacturing | 2023 |
| Amour Hair Salon Limited | Other services | 2016 |
| Ampex Electrical Services Limited | Construction | 2023 |
| Amserv Ltd | Wholesale & retail | 2024 |
| AN Deartháir Caillte Ltd | Hospitality | 2025 |
| Anco Homes CIC | Health & social care | 2024 |
| Anco Integrated Solutions Ltd | Other services | 2018 |
| Anco Real Estate Ltd | Construction | 2018 |
| AND Tiling Ltd | Construction | 2025 |
| Anderson & Maloney Ltd. | Construction | 1998 |
| Anderton Property Group Limited | Real estate | 2023 |
| Andrea Scott Ltd | Other services | 2007 |
| ANF Electrical Consulting Ltd | Construction | 2023 |
| Angelo’S Pizza Ltd | Hospitality | 2025 |
| Anglia Poultry and Food Farms Ltd | Agriculture & fishing | 2019 |
| ANS Roofing Ltd | Construction | 2023 |
| Antbarberstyle Ltd | Other services | 2024 |
| Anthony Bogdan Organs Ltd | Wholesale & retail | 2008 |
| Anton's Refurbish and Rent Ltd | Construction | 2025 |
| Antony Neil Ltd | Real estate | 2019 |
| Anvas Logistics Ltd | Transport & logistics | 2026 |
| AP Mortgage Services Ltd | Financial services | 2019 |
| APB GAS Consultancy Limited | Professional & scientific | 2023 |
| Apdan Limited | Administrative & support | 2016 |
| Apex Geomatics Limited | Construction | 2024 |
| Apex Prime Group Ltd | Construction | 2025 |
| Apointum Construction Services Ltd | Professional & scientific | 2025 |
| Apostle Motors Ltd | Wholesale & retail | 2025 |
| Appliances Direct PVT Ltd | Wholesale & retail | 2025 |
| Appy Little Plums Ltd | Education | 2014 |
| Aquarium Brothers Limited | Construction | 2023 |
| Aquatic Artistry (UK) Ltd | Administrative & support | 2021 |
| Aquila Furniture Limited | Manufacturing | 2008 |
| AR 1 Property Ltd | Real estate | 2022 |
| Arch & Wood Construction & Commercial Ltd | Construction | 2020 |
| ARE Maintenance N.W. Ltd | Administrative & support | 2021 |
| Aria MAX Tailored Events Company Ltd | Administrative & support | 2023 |
| Arrow Leigh Ltd | Hospitality | 2025 |
| Arsawin Ventures Limited | Wholesale & retail | 2025 |
| Art of Barbers Leigh Ltd | Other services | 2025 |
| Art-Town Productions Ltd | Extraterritorial | 2011 |
| Aryjaf Ltd | Hospitality | 2017 |
| ASA Nunn Hair Ltd | Other services | 2025 |
| Asbestos Nationwide Training Limited | Construction | 2019 |
| ASG Energy Services Limited | Construction | 2022 |
| ASH Aesthetics Supplies Ltd | Wholesale & retail | 2023 |
| Ashmel Limited | Health & social care | 2022 |
| Ashton Rose Controls Ltd | Professional & scientific | 2024 |
| Ashworth Events Limited | Administrative & support | 2015 |
| ASM Controls Ltd | Professional & scientific | 2013 |
| Aspire Air Conditioning Solutions Ltd | Energy | 2013 |
| Aspire Driving Instructors Ltd | Education | 2024 |
| Aspire Loft Conversions Limited | Construction | 2013 |
| Astley Hire Limited | Administrative & support | 1985 |
| Astley Moss Equine Bedding Ltd | Agriculture & fishing | 2026 |
| Asurite Ltd | Wholesale & retail | 2026 |
| Atamaii Clothing Limited | Wholesale & retail | 2025 |
| ATC Brickwork Ltd | Construction | 2021 |
| Aticos Hair Studio Limited | Other services | 1996 |
| Atlas Infotech Limited | Information & communication | 2023 |
| Atlas Plastics & Fabrications Ltd | Manufacturing | 2001 |
| ATN Group Limited | Other services | 2019 |
| Attiq Linens Limited | Wholesale & retail | 2023 |
| Augusta Mlay Concepts Limited | Health & social care | 2014 |
| Aunty Almas Ltd | Manufacturing | 2019 |
| Aura Nails Limited | Other services | 2026 |
| Autism in Mind Support Ltd | Health & social care | 2022 |
| Auto Extract Systems (Holdings) Limited | Professional & scientific | 2004 |
| Auto Extract Systems Limited | Construction | 2001 |