| AI Product Development. Ltd | Professional & scientific | 2010 |
| AI Synthesis Ltd | Information & communication | 2026 |
| Aiblock Ltd | Information & communication | 2026 |
| AIC Trading Limited | Wholesale & retail | 2014 |
| Aicoe.Io Ltd | Other services | 2021 |
| Aida Homes Ltd | Real estate | 2025 |
| Aidia Ltd | Information & communication | 2023 |
| Aikam UK Ltd | Wholesale & retail | 2018 |
| AIM (for YOU) Recruitment Ltd | Administrative & support | 2022 |
| Aimse Europe Limited | Other services | 2013 |
| Aimspraxis Ltd | Professional & scientific | 2025 |
| Air B&B Lilchester Ltd | Hospitality | 2022 |
| Air Trading Limited | Wholesale & retail | 2024 |
| Air Vent Holdings Limited | Other services | 2025 |
| Airbench Ltd | Manufacturing | 1993 |
| Aircon One 24/7 Ltd | Construction | 2025 |
| Airlec Solutions Limited | Energy | 2014 |
| Airport Design Consult Ltd | Professional & scientific | 2008 |
| Airport Tyre Service Stansted Limited | Wholesale & retail | 2010 |
| Airvent Contracts Limited | Administrative & support | 2011 |
| Aistan Group Ltd | Manufacturing | 2021 |
| Aistan Ltd | Manufacturing | 2012 |
| Aiste's Promotion Ltd | Other services | 2015 |
| AITICLE-0 Ltd | Wholesale & retail | 2024 |
| Aitsm Ltd | Information & communication | 2025 |
| Aizl Investments Limited | Real estate | 2020 |
| Aizylon Ltd | Wholesale & retail | 2024 |
| AJ Hygienic Interiors Limited | Construction | 2013 |
| AJ Photos and Designs Ltd | Arts & recreation | 2016 |
| Aj&C Limited | Professional & scientific | 2026 |
| AJA Solutions Limited | Hospitality | 2016 |
| Ajar Online Ltd | Professional & scientific | 2025 |
| Ajax Wealth Management Limited | Financial services | 2018 |
| AJC Homeworks Ltd | Other services | 2019 |
| AJD Paraplanning Support Limited | Professional & scientific | 2013 |
| AJD Plastering Ltd | Construction | 2016 |
| AJE Graffix Limited | Other services | 2003 |
| AJE Mechanical Repairs and Solutions Limited | Manufacturing | 2024 |
| Ajev ENG. Ltd | Professional & scientific | 2016 |
| AJF Capital Ltd | Financial services | 2023 |
| AJG Legal Ltd | Professional & scientific | 2023 |
| AJL Theatrical Ltd | Arts & recreation | 2015 |
| AJP Property Holdings Limited | Real estate | 2025 |
| AJS Photographic Ltd | Professional & scientific | 2014 |
| AK Fibreglassing Ltd | Manufacturing | 2023 |
| AK Metals Limited | Wholesale & retail | 2015 |
| AK Voice Systems Limited | Information & communication | 2003 |
| AKA Garage & Parts Ltd | Wholesale & retail | 2023 |
| Akersloot Court Management Limited | Households | 2000 |
| AKH Services Ltd | Professional & scientific | 2015 |
| Akia Homes Ltd | Real estate | 2024 |
| AKL Construction Ltd | Construction | 2017 |
| AKR Trading 1942 Ltd | Wholesale & retail | 2025 |
| AKS (LDN) Limited | Hospitality | 2018 |
| AKS (LDN) Subs Ltd | Hospitality | 2021 |
| AKS Corp Properties Ltd | Real estate | 2021 |
| AKS Corporation Ltd | Administrative & support | 2021 |
| AKS7 Properties Ltd | Real estate | 2020 |
| Akshardia Ltd | Other services | 2025 |
| AKT Ventures Ltd | Professional & scientific | 2020 |
| AL Arabia Ltd | Professional & scientific | 2017 |
| AL Bourke Ltd | Construction | 2016 |
| AL Kero Limited | Professional & scientific | 2025 |
| AL Medinah UK Limited | Wholesale & retail | 2019 |
| AL Pacino Italy Ltd | Hospitality | 2021 |
| AL Pearson Investments Limited | Administrative & support | 2017 |
| Al&G Logistics Limited | Transport & logistics | 2024 |
| Al&G Properties Limited | Real estate | 2021 |
| Al&G Services Limited | Health & social care | 2022 |
| Al-Moeed Foods Limited | Hospitality | 2024 |
| Aladdin's Cars Colchester Limited | Transport & logistics | 2023 |
| Alan Bender Limited | Construction | 2002 |
| Alan Critchley Consulting Ltd | Health & social care | 2011 |
| Alan Hill Financial Planning Limited | Financial services | 2013 |
| Alan Lingley Inspections Limited | Professional & scientific | 2007 |
| Alansons Shipping Limited | Administrative & support | 1984 |
| Alappatt Consultancy Ltd | Health & social care | 2024 |
| Alaturka Barbers Ltd | Other services | 2019 |
| Albany Gardens Residents Company Limited | Households | 2003 |
| Albex Future Limited | Health & social care | 2015 |
| Albion Global Limited | Professional & scientific | 2025 |
| Albris Group Ltd | Professional & scientific | 2024 |
| Albris Solutions Ltd | Financial services | 2024 |
| Alburj Medical Services Limited | Health & social care | 2024 |
| Alburj Property Ltd | Real estate | 2021 |
| ALC Building Services Ltd | Construction | 2018 |
| ALC Property Developers Limited | Administrative & support | 2003 |
| Alchamis Ltd | Professional & scientific | 2021 |
| Alcove Limited | Information & communication | 2014 |
| Alder Park Limited | Administrative & support | 2021 |
| Aldercar Investments Limited | Real estate | 2020 |
| Aldgate Manor Services Ltd | Construction | 2017 |
| Aldous Electrical Felixstowe Limited | Construction | 2015 |
| Aldred Mitchell Ltd | Administrative & support | 2015 |
| Alekya Catering Ltd | Hospitality | 2026 |
| Alex Day Associates Limited | Professional & scientific | 2022 |
| Alex Lloyd Wealth Management Ltd | Professional & scientific | 2021 |
| Alex Mortgages Ltd | Professional & scientific | 2019 |
| Alex UK Properties Ltd | Real estate | 2018 |
| Alexander Builders (UK) Ltd | Construction | 2002 |