| Alpine Driveways Limited | Construction | 2005 |
| Alsager Limited | Real estate | 1994 |
| Alsaour Limited | Information & communication | 2021 |
| ALT ICT Group Ltd | Information & communication | 2023 |
| Altroy Ltd | Professional & scientific | 2002 |
| Altudo Limited | Information & communication | 2018 |
| Altus Records Limited | Information & communication | 1998 |
| Alviez Capital Ltd | Financial services | 2023 |
| Alviez Ltd | Wholesale & retail | 2023 |
| Alviez Publishing Ltd. | Information & communication | 2017 |
| Alviz Ltd | Wholesale & retail | 2021 |
| ALY and Nico Ltd | Wholesale & retail | 2021 |
| Alyaan Cars Ltd | Wholesale & retail | 2018 |
| Amanda Jane LEE Ltd | Professional & scientific | 2013 |
| Amber Business Solutions (London) Ltd | Professional & scientific | 2021 |
| Amber Business Solutions (Ruislip) Ltd | Information & communication | 2024 |
| Amber Business Solutions (UK) Ltd | Professional & scientific | 2021 |
| Amber Property Solutions Ltd | Real estate | 2023 |
| Amberose Building Construction Ltd | Construction | 2014 |
| AMC Paving & Building Limited | Construction | 2013 |
| Amclb Services Limited | Construction | 2019 |
| Amco Care Limited | Extraterritorial | 2019 |
| Amco Recruits Limited | Administrative & support | 2018 |
| Amcommerce Limited | Wholesale & retail | 2021 |
| Amek Electrical Services Limited | Construction | 1997 |
| Amello Music Ltd | Wholesale & retail | 2023 |
| Ameva Limited | Other services | 2025 |
| Amgh Capital Ltd | Real estate | 2024 |
| AMH London International Trading Ltd | Transport & logistics | 2025 |
| Amir & Co Beauty Atelier Ltd | Other services | 2025 |
| Amjson's Enterprise Limited | Wholesale & retail | 2026 |
| Amlak Real Estate Ltd | Real estate | 2023 |
| Amlevco Limited | Administrative & support | 2014 |
| Amma Property Holdings Ltd | Real estate | 2026 |
| Amman Executive Chauffeur & Airport Transfers Ltd | Transport & logistics | 2026 |
| Amore Jewels Ltd | Wholesale & retail | 2024 |
| Amori Business Solutions Limited | Administrative & support | 2006 |
| AMP Legal Services Limited | Professional & scientific | 2023 |
| AMR Consultancy Services Limited | Mining & quarrying | 2014 |
| Amraj Investments Limited | Real estate | 2021 |
| Amramfx Limited | Financial services | 2025 |
| AMS Consulting Group Ltd | Wholesale & retail | 2019 |
| AMS Weaire Ltd | Manufacturing | 2015 |
| AMU UK Trading Ltd | Other services | 2025 |
| Amveen Limited | Wholesale & retail | 2023 |
| AN Imperial Build Limited | Construction | 2026 |
| AN JI Global Infinity Trading Co., Ltd | Wholesale & retail | 2024 |
| AN News & Cafe Ltd | Wholesale & retail | 2016 |
| Anakena Ltd | Information & communication | 2020 |
| Analiving Ltd | Real estate | 2024 |
| Analysts Journal Ltd | Information & communication | 2022 |
| Anand & Sons Investments Ltd. | Real estate | 2024 |
| Anand Punja Consulting Ltd | Professional & scientific | 2020 |
| Anant Design and Build Limited | Construction | 2024 |
| ANB Natural Ltd | Wholesale & retail | 2025 |
| Anda Saku Ltd | Professional & scientific | 2020 |
| Andelitt Media Services Ltd | Administrative & support | 2014 |
| Ando Services Ltd | Administrative & support | 2018 |
| Andreea Aesthetic Studio Ltd | Other services | 2026 |
| Andrew Hennessey Studios Limited | Administrative & support | 2007 |
| Andrewradc Ltd | Professional & scientific | 2025 |
| Andri Solution Ltd | Administrative & support | 2026 |
| Andro 76 Ltd | Construction | 2016 |
| Andtrans Ltd | Transport & logistics | 2019 |
| Anek Investment Ltd | Real estate | 2022 |
| Anewgarden Ltd | Agriculture & fishing | 2013 |
| Angel Accountancy Services Limited | Professional & scientific | 2012 |
| Angel Accountants Ltd | Professional & scientific | 2018 |
| Angel and KEN Limited | Extraterritorial | 2021 |
| Angel Apparel Garments Limited | Administrative & support | 2023 |
| Anglia Luxury Kennels Limited | Agriculture & fishing | 2025 |
| Anglia Natural Stone Suppliers Limited | Wholesale & retail | 2018 |
| Anglo Australian Radiology Limited | Health & social care | 2021 |
| Anglohaul Ltd | Transport & logistics | 2026 |
| Anhui Witop Biotech Co., Ltd | Extraterritorial | 2021 |
| Aniram Angell Ltd | Construction | 2013 |
| Anisorian Limited | Professional & scientific | 2019 |
| Anivin Ltd | Health & social care | 2024 |
| Anlj Ltd | Information & communication | 2026 |
| Ann-Marie Burke Children's OT Ltd | Health & social care | 2025 |
| Ann-Marie Rebecca Balcombe Ltd. | Extraterritorial | 2021 |
| Annie Katchinska Limited | Health & social care | 2025 |
| Annon Construction Limited | Construction | 2013 |
| Anntiara Properties Ltd | Real estate | 2024 |
| ANP Shipping Co., Ltd | Extraterritorial | 2022 |
| Ansa PVT Ltd | Administrative & support | 2019 |
| Ansenda Industry Co., Ltd | Wholesale & retail | 2022 |
| Anslip (U.K.) Limited | Construction | 1970 |
| Antalia KB Ltd | Hospitality | 2025 |
| Anthony Mills Tennis Ltd | Education | 2026 |
| Anthony Paul Maintenance Ltd | Construction | 2016 |
| Anticus Technologies Ltd | Information & communication | 2025 |
| Antilles African Anthurium | Education | 2022 |
| Antonio Investments Ltd | Real estate | 2024 |
| ANY Medical Ltd | Health & social care | 2024 |
| Anzaltech Limited | Other services | 2025 |
| Aochang Technology Co., Ltd | Wholesale & retail | 2024 |
| Aoulink Digital Limited | Information & communication | 2026 |
| AP Events Limited | Administrative & support | 2009 |
| AP Exhibitions Limited | Administrative & support | 2012 |