| Airtrust Limited | Extraterritorial | 1991 |
| AJA Installations Ltd | Construction | 2022 |
| AJB Detailing Ltd | Administrative & support | 2023 |
| AJD Investment Properties Ltd | Real estate | 2025 |
| AJM Smart Developments Ltd | Other services | 2016 |
| Ajpr Holdings Limited | Financial services | 2018 |
| AJR (Hi-Ab Hire) Limited | Administrative & support | 2003 |
| AK3 Couriers Ltd | Transport & logistics | 2013 |
| AK3 Investments Limited | Real estate | 2018 |
| AKB Global Ltd | Construction | 2025 |
| AKB Property Management Limited | Real estate | 2018 |
| AKC Comms Limited | Information & communication | 2018 |
| AL Products Ltd | Wholesale & retail | 2022 |
| Alan Timmins & Co (Wt&S) Ltd | Real estate | 2021 |
| Alayé Ltd | Wholesale & retail | 2025 |
| Albany Imaging Limited | Health & social care | 2024 |
| Alcomet 2019 Limited | Financial services | 2019 |
| Alcomet 2022 Limited | Financial services | 2022 |
| Alcomet Holdings Limited | Financial services | 2015 |
| Alcomet Limited | Wholesale & retail | 1998 |
| ALE Hub (K'Ford) Limited | Hospitality | 2025 |
| Aleega Homes Limited | Hospitality | 2022 |
| Alex Westley Hewitt (Holdings) Ltd | Administrative & support | 2019 |
| Alexander & Anastasia Holdings Ltd | Real estate | 2023 |
| Alexander Comley Limited | Manufacturing | 2017 |
| Alexandra House Care Services Limited | Professional & scientific | 2003 |
| Alimentari Ltd | Wholesale & retail | 2025 |
| Alizay Limited | Health & social care | 2016 |
| ALL Building & Windows Limited | Construction | 2020 |
| ALL Car Buyers Ltd | Wholesale & retail | 2015 |
| ALL for Kids Ltd | Arts & recreation | 2025 |
| ALL in One Building Contractors Ltd | Construction | 2023 |
| ALL Metal Fabrications & Installations Limited | Professional & scientific | 2025 |
| ALL Seasons Contracting Co. Limited | Construction | 1992 |
| ALL Seasons Surfacing Limited | Construction | 1973 |
| ALL Stars Clubs CIC | Arts & recreation | 2025 |
| Alliance Blinds Limited | Wholesale & retail | 2015 |
| Allied Machine & Engineering Co. (Europe) Ltd. | Wholesale & retail | 1992 |
| Allied Maxcut Engineering Co. Limited | Wholesale & retail | 1998 |
| Alma Controls Ltd | Manufacturing | 2023 |
| Almanac Accountancy Ltd | Professional & scientific | 2022 |
| Alpha Bricklaying & Construction Ltd | Construction | 2023 |
| Alpha Design Ltd | Professional & scientific | 2004 |
| Alpha Fish Construction Limited | Construction | 2017 |
| Alphus Limited | Administrative & support | 2019 |
| Altitude Lift Solutions Ltd | Professional & scientific | 2024 |
| Aluminium Special Products Limited | Manufacturing | 2003 |
| Alvechurch NO 1 Limited | Professional & scientific | 2025 |
| Amanda Bolger Coaching Limited | Professional & scientific | 2007 |
| Amar and Sudha Limited | Households | 2021 |
| Ambear Restaurants Limited | Hospitality | 2023 |
| AMC Restaurants Ltd | Hospitality | 2023 |
| AMC Utilities Ltd | Construction | 2026 |
| Amelie Design LLP | | 2015 |
| Amie Otoole Enterprises Limited | Hospitality | 2019 |
| Amigo Investments Ltd | Real estate | 2019 |
| Amoeba Associates Ltd | Construction | 2018 |
| Ampk Limited | Health & social care | 2024 |
| Amptronik Control Systems Limited | Construction | 1982 |
| AMS Scaffold Services Ltd | Other services | 2020 |
| Amsale Products Limited | Wholesale & retail | 2016 |
| Anacapri Management Company Limited | Households | 2019 |
| Anchor & Beam Ltd | Real estate | 2026 |
| Andrew Page Tyres Ltd | Professional & scientific | 2017 |
| Andy's Auto and MOT Centre Limited | Wholesale & retail | 2009 |
| Anika Property Limited | Real estate | 2020 |
| Another Artist Co Limited | Arts & recreation | 2021 |
| ANP Property Holdings Ltd | Households | 2024 |
| ANP Smith Limited | Health & social care | 2016 |
| Anpconsultant Limited | Health & social care | 2013 |
| ANT Access International Limited | Manufacturing | 2015 |
| ANT Tiling Ltd | Construction | 2024 |
| Antidote Hair Ltd | Other services | 2020 |
| Antique and Vintage Ltd | Wholesale & retail | 2022 |
| AO Cooling Ltd | Construction | 2024 |
| AP Implants Ltd | Other services | 2024 |
| AP Roofing & Building Ltd | Construction | 2019 |
| AP Sweet Home Improvements Limited | Construction | 2026 |
| Apex Roofing (West Midlands) Ltd | Construction | 2026 |
| APM Market Limited | Manufacturing | 2020 |
| Applications & Solutions (UK) Limited | Professional & scientific | 2018 |
| Approved Roofing and Driveways Limited | Construction | 2021 |
| APZ UK Limited | Wholesale & retail | 2009 |
| Aqua Heat (Midlands) Ltd | Construction | 2026 |
| Aqua Installation Ltd | Construction | 2024 |
| AR Bespoke Kitchens Ltd | Professional & scientific | 2026 |
| Architectural Metalwork Draughting Limited | Professional & scientific | 2009 |
| ARH Installations Ltd | Construction | 2013 |
| ARH Investment Properties Limited | Real estate | 2022 |
| Arise Church Ltd. | Other services | 2007 |
| Ariver Consultancy Ltd | Professional & scientific | 2024 |
| ARJ Ductwork Ltd | Construction | 2019 |
| ARK Hair and Beauty Ltd | Other services | 2023 |
| Arkwrights Hardware Ltd | Wholesale & retail | 2013 |
| Armadillocks Ltd | Manufacturing | 2013 |
| Art and FLO Ltd | Administrative & support | 2012 |
| Art by MR J Limited | Arts & recreation | 2021 |
| Arthouse Hair ED Ltd | Education | 2026 |
| Arxera Ltd | Information & communication | 2025 |
| ASA Metal Products Ltd | Wholesale & retail | 2023 |