| Akron Estate Ltd | Real estate | 2025 |
| Akyn Studio Limited | Manufacturing | 2021 |
| AL Barka Trading Ltd | Wholesale & retail | 2025 |
| Al-Shafi Healthcare Ltd | Health & social care | 2025 |
| AL18 Limited | Other services | 2020 |
| Albany Court Management Co. (Rainham) Limited | Real estate | 1987 |
| Albelectrics Limited | Construction | 2013 |
| Albita Ltd | Hospitality | 2023 |
| Alchattha Excellency Ltd | Hospitality | 2023 |
| ALE and PIE Company Limited | Professional & scientific | 2013 |
| Alessandro Pietrosanti Ltd | Information & communication | 2022 |
| Alex Pjetri Construction Ltd | Construction | 2022 |
| Alexander House Care Limited | Financial services | 2016 |
| Alexander Real Estate (Essex) Limited | Real estate | 2026 |
| Alexanders Property Solutions Ltd | Real estate | 2023 |
| Alexandra Finance Management Limited | Financial services | 2019 |
| Alexandra Yacht Club Limited | Arts & recreation | 1979 |
| Algram Group Limited | Manufacturing | 1987 |
| ALH Management Consulting Limited | Professional & scientific | 2023 |
| Alice Art Co. Limited | Arts & recreation | 2022 |
| Alifted Community Initiative | Agriculture & fishing | 2016 |
| Alison Charles Ltd | Professional & scientific | 2019 |
| Alison Stone Surveyors Limited | Professional & scientific | 2019 |
| Alivedots.Com Ltd | Information & communication | 2025 |
| Aljo Fruit&Veg Limited | Wholesale & retail | 2014 |
| Alkonost Ltd | Information & communication | 2023 |
| ALL Global Services Ltd | Transport & logistics | 2018 |
| ALL Berts Limited | Hospitality | 2020 |
| ALL in IT Ltd | Information & communication | 2019 |
| ALL Salts Limited | Wholesale & retail | 2021 |
| ALL Things Scene Ltd | Information & communication | 2008 |
| ALL YOU Need Mortgages Limited | Financial services | 2016 |
| ALL4ONE Care Services Nightingale House Limited | Health & social care | 2024 |
| ALL4ONE4ALL Limited | Education | 2022 |
| Allclaims Consultancy Limited | Financial services | 2021 |
| Alleda Limited | Other services | 2023 |
| Alley Cat Properties Limited | Real estate | 2021 |
| Allied (a) Consultancy Limited | Professional & scientific | 2013 |
| Alloy Media Ltd | Administrative & support | 2018 |
| Alltech Plumbing Ltd | Other services | 2016 |
| Ally Gunn Limited | Administrative & support | 2018 |
| Almma Properties Ltd | Real estate | 2026 |
| ALMO6 Massage Parlour Ltd Limited | Other services | 2025 |
| Aloha Lounge Ltd | Hospitality | 2021 |
| Alpha Access Ltd | Construction | 2023 |
| Alpha and Omega Developments Ltd | Construction | 2020 |
| Alpha Intelligence Consultant (UK) Ltd | Information & communication | 2026 |
| Alpha Outreach and Support CIC | Real estate | 2025 |
| Alpha Premier Limited | Administrative & support | 2024 |
| Alpha Rose Construction Limited | Construction | 2024 |
| Alpha Route Ltd | Information & communication | 2024 |
| Alphascaled Technology Limited | Information & communication | 2025 |
| Alpine Construction Essex Limited | Construction | 1999 |
| Alpine Construction Holdings Limited | Financial services | 2020 |
| Alpine Film Productions Limited | Information & communication | 2006 |
| Alpine Investment Property Limited | Real estate | 2023 |
| Altair Consulting Ltd | Professional & scientific | 2025 |
| Altun Automotive Limited | Wholesale & retail | 2025 |
| Alund Properties Ltd | Households | 2025 |
| AM1 Construction Limited | Construction | 2024 |
| Amanah Learning Ltd | Education | 2025 |
| Amanany Limited | Health & social care | 2023 |
| Amapola London Limited | Wholesale & retail | 2021 |
| Amateur Mixologist Ltd | Information & communication | 2024 |
| Amber Chicken Limited | Hospitality | 2026 |
| Amber Finance Limited | Financial services | 2007 |
| Amber Wealth Management Limited | Financial services | 2025 |
| Ambleside Engineering Ltd | Construction | 2025 |
| Ambulance Solutions Ltd | Health & social care | 2017 |
| Amdex Solutions Limited | Information & communication | 2002 |
| Amethyst Accounting Services Limited | Professional & scientific | 2007 |
| AMG Aspen Ltd | Real estate | 2021 |
| AMG Investment Properties Limited | Real estate | 2012 |
| Amicrest Recovery 52 Limited | Real estate | 2000 |
| Amio Corporate Services Limited | Administrative & support | 2019 |
| AMP Baba Ltd | Wholesale & retail | 2026 |
| AMY Powney Ltd | Wholesale & retail | 2026 |
| Amzc Limited | Administrative & support | 2019 |
| Anabaa Limited | Financial services | 2011 |
| Anair Ltd | Real estate | 2024 |
| Andalucia Web Solutions Limited | Information & communication | 2004 |
| Anderson GUM Bins Ltd | Manufacturing | 2008 |
| Andorina Limited | Construction | 2018 |
| Andrew James Construction Ltd | Construction | 2020 |
| Andrew Llewellyn Limited | Wholesale & retail | 2002 |
| Andromeda Real Estate Ltd | Real estate | 2025 |
| Anecleaning Ltd | Administrative & support | 2023 |
| Anetic Group Limited | Administrative & support | 2020 |
| Anetic Ltd | Administrative & support | 2020 |
| Anetic Services Ltd | Administrative & support | 2007 |
| Anetic Solutions Limited | Administrative & support | 2024 |
| Angela Louise Bowditch Limited | Extraterritorial | 2024 |
| Angela Louise Paul Ltd | Extraterritorial | 2024 |
| Anglian Auto Recovery Limited | Wholesale & retail | 1999 |
| Anglian Business Hub Limited | Administrative & support | 2016 |
| Anglo American Ice Cream Limited | Professional & scientific | 2001 |
| Anglo-Pol Transport Ltd | Transport & logistics | 2004 |
| Angry Smash Ltd | Arts & recreation | 2024 |
| Anima Pura Beauty Ltd | Other services | 2021 |
| Anima Pura Hair Ltd | Other services | 2021 |