| AMK Developments Limited | Health & social care | 2017 |
| AMK Education Limited | Education | 2025 |
| AMK Laboratories Ltd | Manufacturing | 2025 |
| AMK Orthodontics Limited | Health & social care | 2018 |
| Amma Foods (UK) Private Limited | Wholesale & retail | 2024 |
| Amory Limited | Construction | 2024 |
| AMP Strategists Limited | Administrative & support | 2022 |
| Amp/Elec Limited | Construction | 2011 |
| Amphora Cafe Limited | Hospitality | 2018 |
| Amplify Technology Group Limited | Information & communication | 2017 |
| Amsa Solutions Ltd | Information & communication | 2016 |
| Amsak Property Limited | Real estate | 2019 |
| Amsha Apps Ltd | Information & communication | 2026 |
| Amsk Holdings Ltd | Professional & scientific | 2024 |
| AMT Ophth Ltd | Health & social care | 2023 |
| AMY & SAM Limited | Real estate | 2025 |
| Amysoft Limited | Information & communication | 2012 |
| AN Dwellings Limited | Real estate | 2020 |
| Anaesthesia and Intensive Care Medics Ltd | Health & social care | 2022 |
| Anand Health Ltd | Health & social care | 2026 |
| Anatolia Foods Limited | Wholesale & retail | 2006 |
| Anavio Limited | Hospitality | 2003 |
| Anconsultants Limited | Information & communication | 2010 |
| Anderby Properties Limited | Administrative & support | 2004 |
| Anderson Housing Developments Limited | Construction | 2020 |
| Anderson Property Limited | Real estate | 2013 |
| Andiamo Travel Ltd. | Administrative & support | 2011 |
| Ando Management Limited | Real estate | 2022 |
| Andreas Wine Trading Ltd | Manufacturing | 2015 |
| Andrew Smith Production Services Limited | Arts & recreation | 2013 |
| Andy and the Band Limited | Information & communication | 2019 |
| Andy Guest & Co Ltd | Real estate | 2021 |
| Aneksin Enterprise Ltd | Health & social care | 2025 |
| Anestis Lefkopoulos Limited | Health & social care | 2010 |
| Animal Direction Ltd | Professional & scientific | 2019 |
| Ankershousing Ltd | Professional & scientific | 2023 |
| Annelie Ruther Ltd | Wholesale & retail | 2022 |
| Anoaa Limited | Professional & scientific | 2015 |
| Anshz Ltd | Health & social care | 2020 |
| Anson Consulting Limited | Information & communication | 2024 |
| Anstaar Estates PVT Limited | Real estate | 2022 |
| Anthony Grindrod Associates Ltd | Administrative & support | 2015 |
| Anthony Robinson Solicitors Limited | Professional & scientific | 2012 |
| Antonia Investments Limited | Professional & scientific | 2022 |
| Anvi Digitals Limited | Administrative & support | 2025 |
| Anvi Holdings Limited | Real estate | 2020 |
| Anwita Medical Ltd | Health & social care | 2020 |
| AOM Investments Ltd | Information & communication | 2020 |
| APC Caravans Limited | Administrative & support | 2024 |
| Apex Scaffold and Access Limited | Construction | 2024 |
| Apex Trading Supplies Ltd | Wholesale & retail | 2024 |
| Apex United Limited | Education | 2024 |
| APG Finance Limited | Professional & scientific | 2026 |
| Apis Framing Limited | Other services | 2019 |
| Apoc IT Solutions Limited | Information & communication | 2010 |
| App Marketing Limited | Information & communication | 2023 |
| Appbridge Consultancy Services Limited | Information & communication | 2016 |
| Appleberry Stories Ltd | Wholesale & retail | 2025 |
| Appleton Kitchens Limited | Wholesale & retail | 2016 |
| Appleton Properties NW Ltd | Real estate | 2018 |
| Appleyard & Trew LLP | | 2003 |
| April.Uk.Logistics Ltd | Construction | 2018 |
| Aptkidz Ltd | Professional & scientific | 2016 |
| Apts Property Limited | Real estate | 2025 |
| Apts Services Limited | Administrative & support | 2022 |
| Aqua Catalysis Limited | Professional & scientific | 2023 |
| Aqua Sativa Ltd | Other services | 2011 |
| Aquaguard Water Compliance Ltd | Professional & scientific | 2026 |
| Aquascapes & Landscaping Limited | Construction | 2014 |
| Aquaviva Foods Ltd | Wholesale & retail | 2026 |
| Aquawave Plumbing Limited | Construction | 2025 |
| Aqueous Consulting Limited | Information & communication | 2005 |
| AR Creative Ltd | Professional & scientific | 2025 |
| AR MCR Ltd | Real estate | 2023 |
| Arabian Knight AK Ltd | Wholesale & retail | 2026 |
| Arabic Translation Solutions Ltd | Professional & scientific | 2018 |
| Arabic VMR Ltd | Hospitality | 2024 |
| Arali Ltd. | Information & communication | 2016 |
| Aramis Tree Limited | Real estate | 2022 |
| Aras Civils Limited | Professional & scientific | 2020 |
| Araz Properties Limited | Real estate | 1987 |
| Arbodirect Limited | Wholesale & retail | 2015 |
| Arbor Porta Investments Limited | Professional & scientific | 2023 |
| ARC4 Limited | Professional & scientific | 2007 |
| Arcana Financial Consulting Limited | Financial services | 2016 |
| Archents UK Ltd | Information & communication | 2011 |
| Archon Innovations Ltd | Extraterritorial | 2019 |
| Archybold Limited | Information & communication | 2016 |
| Archys Rigging Ltd | Information & communication | 2021 |
| Arcot Interiors Limited | Wholesale & retail | 2010 |
| Arcus Consulting LLP | | 2003 |
| Ardmore 07469436 Limited | Professional & scientific | 2010 |
| Areei Ltd | Wholesale & retail | 2023 |
| Arena House Enterprises Limited | Real estate | 2003 |
| Arena House Limited | Real estate | 2002 |
| Arenem Ltd | Professional & scientific | 2024 |
| Arete Data & Analytics Ltd | Information & communication | 2025 |
| Ariens Investments Limited | Professional & scientific | 2026 |
| Arima Medical Services Limited | Health & social care | 2014 |
| Aristo Tots Nursery School (LB) Ltd | Administrative & support | 2014 |