| Ammax Logistics Limited | Transport & logistics | 2010 |
| Amoni Power Solutions Ltd | Construction | 2025 |
| Amosadisa Limited | Other services | 2022 |
| AMP Interior Limited | Construction | 2009 |
| AMP Joinery Limited | Manufacturing | 2021 |
| Ampus Electrical Limited | Construction | 2023 |
| Amr-Precision- Ltd | Professional & scientific | 2026 |
| Amrit Wellbeing Ltd | Health & social care | 2022 |
| Amylan Properties Limited | Real estate | 2018 |
| ANA Bowness Ltd | Health & social care | 2026 |
| ANA Child Minding Services Ltd | Health & social care | 2022 |
| Analytica Scientific Ltd | Wholesale & retail | 2024 |
| Anatolian Trader Limited | Wholesale & retail | 2011 |
| Anaya Properties Ltd | Real estate | 2020 |
| Anaya Residential Limited | Real estate | 2024 |
| ANB Works Limited | Construction | 2025 |
| Anchored Ascent Ltd | Information & communication | 2026 |
| AND Posters Limited | Professional & scientific | 2019 |
| Anderson Electrical-Technical Services Limited | Administrative & support | 2014 |
| Anderson Properties London Limited | Real estate | 2026 |
| Andrew Chater & Co Limited | Real estate | 2015 |
| Andrew Heap Consultants Limited | Administrative & support | 2013 |
| Andy Simpson Post Production Services Limited | Arts & recreation | 2013 |
| Aneesah Mahjabeen Organisation (AMO) Ltd | Other services | 2025 |
| Anfs Advisors Ltd | Information & communication | 2024 |
| ANG Properties Limited | Real estate | 2005 |
| Angad Properties Limited | Real estate | 2020 |
| Angeethi Limited | Hospitality | 2026 |
| Angel Property Holdings (London) Limited | Real estate | 2025 |
| ANGEL5 Ltd | Health & social care | 2023 |
| Angela Sharma Law Ltd | Professional & scientific | 2023 |
| Angelic Nails ELM Park Limited | Other services | 2025 |
| Anglia Firewood Limited | Extraterritorial | 2013 |
| Anis Construction Ltd | Construction | 2020 |
| Annao Housekeeping Limited | Administrative & support | 2021 |
| Annon Homes Ltd | Real estate | 2023 |
| Annyworld Limited | Wholesale & retail | 2023 |
| ANS Accountants Limited | Information & communication | 2014 |
| ANS Safety Ltd | Professional & scientific | 2024 |
| Ansag Limited | Real estate | 2016 |
| Ansari Innovations Ltd | Wholesale & retail | 2025 |
| Anthony Clifford Studios Limited | Arts & recreation | 2003 |
| Anthony MAY Group Limited | Real estate | 2025 |
| Anton Jeffes Ltd | Professional & scientific | 2021 |
| Anushka Shaurya Limited | Real estate | 2023 |
| Anwar Consultants Ltd | Professional & scientific | 2011 |
| Anysomething Photography Limited | Professional & scientific | 2022 |
| Anzi & Co Ltd | Transport & logistics | 2020 |
| AOC (Pipework) Limited | Construction | 2010 |
| AP Building and Civil Engineering Limited | Construction | 2025 |
| AP Dental Limited | Health & social care | 2008 |
| AP Send CEO Network C.I.C. | Education | 2024 |
| Apartment 27 Management Ltd | Real estate | 2025 |
| APB Beard Ltd | Arts & recreation | 2018 |
| Apchem Ltd | Other services | 2013 |
| APD Consultancy Limited | Information & communication | 2004 |
| Apello General Construction Limited | Construction | 2018 |
| Aperaplumbs Limited | Administrative & support | 2005 |
| Apex LD Limited | Construction | 2026 |
| Apex Real Limited | Administrative & support | 2011 |
| Apex Spray Ltd | Construction | 2024 |
| Apex Thermal Insulation Ltd | Construction | 2023 |
| Apex Waste Solutions Limited | Manufacturing | 2024 |
| Apexview Properties Ltd | Real estate | 2023 |
| Apexview Property Management Services Ltd | Real estate | 2025 |
| APL Healthcare Limited | Health & social care | 2026 |
| Aplex Contracts Limited | Construction | 2015 |
| Apple Juice Entertainment Limited | Arts & recreation | 2022 |
| Apple Links Consultancy Limited | Administrative & support | 2017 |
| Apple Property Block Management Ltd | Real estate | 2024 |
| Apple Property Services Limited | Real estate | 2016 |
| Apple Property Services Sales Ltd | Real estate | 2021 |
| Applebee Advisory Limited | Professional & scientific | 2018 |
| Applied Contracts Limited | Administrative & support | 1992 |
| APS Hornchurch Ltd | Real estate | 2018 |
| APW Property Group Ltd | Real estate | 2024 |
| Aquarius Developments Ltd | Construction | 2010 |
| Aquascapes Limited | Administrative & support | 2002 |
| Aquasolve (London) Limited | Administrative & support | 2009 |
| Aquatek Mechanical Services Ltd | Construction | 2019 |
| AR Houchell Holdings Ltd | Households | 2022 |
| AR Khanna Ltd | Health & social care | 2023 |
| AR Lyne Motors Ltd | Wholesale & retail | 2025 |
| AR Property Maintenance Ltd | Construction | 2013 |
| Aram Supplier Ltd | Transport & logistics | 2024 |
| Aranmanai Limited | Real estate | 2020 |
| ARAS19 Limited | Hospitality | 2026 |
| Arbes LUX Stays Limited | Real estate | 2025 |
| ARC Electrical Services Limited | Construction | 2022 |
| ARC Solution Flooring Limited | Construction | 2025 |
| Archdor Ltd | Construction | 2022 |
| Arctc Energy Ltd | Professional & scientific | 2026 |
| Arden Advisory Ltd | Professional & scientific | 2023 |
| Ardleigh Improvements Limited | Construction | 2002 |
| Arena Food Centre Ltd | Wholesale & retail | 2024 |
| Arianmilan Property Holdings Limited | Real estate | 2024 |
| Ariapour Ltd | Financial services | 2024 |
| Arias Renovations Ltd | Construction | 2025 |
| Arik Care UK Ltd | Health & social care | 2022 |
| Arisha & Adiyan Limited | Real estate | 2024 |