| Amplexus Consultancy Ltd. | Professional & scientific | 2014 |
| Amplify Yourself Ltd | Information & communication | 2026 |
| Amplifyplus Limited | Professional & scientific | 2023 |
| Ampofo Intelligence Ltd | Professional & scientific | 2023 |
| Ampton Hall Estates | Agriculture & fishing | 1937 |
| Amrhys Limited | Professional & scientific | 2026 |
| Amrzone Ltd | Wholesale & retail | 2025 |
| AMS High Limited | Information & communication | 2019 |
| AMS Supply Chain Limited | Professional & scientific | 2022 |
| AMS Tech Solution Limited | Information & communication | 2025 |
| Amscentric Limited | Wholesale & retail | 2020 |
| Amtro Limited | Wholesale & retail | 2024 |
| Amtus Ltd | Wholesale & retail | 2023 |
| Amty Holdings Limited | Wholesale & retail | 2025 |
| Amusement Tables Ltd | Wholesale & retail | 2023 |
| Amvp Limited | Transport & logistics | 2017 |
| AMY Siddaway Qualitative Research Ltd | Professional & scientific | 2025 |
| AMZ Auto Transport Ltd | Transport & logistics | 2019 |
| AMZ Tech Ltd | Wholesale & retail | 2022 |
| AN NUR Studios Ltd | Information & communication | 2025 |
| AN United Solutions Ltd | Wholesale & retail | 2025 |
| An-Edit Ltd | Wholesale & retail | 2021 |
| Anagram Audio Ltd | Wholesale & retail | 2019 |
| Anakosmos Group Ltd | Information & communication | 2023 |
| Analytics SEO Limited | Information & communication | 2006 |
| Anamora Ltd | Professional & scientific | 2026 |
| Anamta Fahad Ltd | Wholesale & retail | 2025 |
| Anas Momin Ltd | Wholesale & retail | 2023 |
| Anastar Properties Limited | Real estate | 2002 |
| Anaya PVT Ltd | Financial services | 2022 |
| Anboise Ltd | Wholesale & retail | 2020 |
| ANC Estates Ltd | Real estate | 2025 |
| Anchor Care and Education Ltd | Health & social care | 2020 |
| Anchor Care Holdings Ltd | Financial services | 2025 |
| Anchor Challenge Ltd | Education | 2022 |
| Ancient Earth Limited | Wholesale & retail | 2023 |
| Ancient Key Residents Company Limited | Households | 2007 |
| Ancient Orchard Properties Limited | Real estate | 2007 |
| Ancrypt Ltd | Information & communication | 2022 |
| AND Other Ways (UK) Ltd | Information & communication | 2026 |
| AND the Rest Productions Limited | Education | 2025 |
| Andalucian Olive Company Ltd | Wholesale & retail | 2021 |
| Andalus Road Limited | Real estate | 2018 |
| Anderson Centre Management (Bury ST. Edmunds) Limited | Real estate | 1997 |
| Anderson Vehicle Management Limited | Wholesale & retail | 2004 |
| Andersons Landscape and Maintenance Ltd | Administrative & support | 2019 |
| Anditech Ltd | Wholesale & retail | 2024 |
| Andrea James Legal Limited | Professional & scientific | 2016 |
| Andrea Technology Solutions Ltd | Wholesale & retail | 2026 |
| Andreea Ignat Ltd | Health & social care | 2018 |
| Andrew Eichholz Services Ltd | Real estate | 2026 |
| Andrew Frear Building and Carpentry Ltd | Construction | 2025 |
| Andrew Frost Cars Limited | Wholesale & retail | 2012 |
| Andrew Howarth Consulting Ltd | Professional & scientific | 2020 |
| Andrew Lipinski Limited | Other services | 2018 |
| Andrew Mills Financial Services Limited | Financial services | 2014 |
| Andrew P Cooper Holdings Limited | Financial services | 2018 |
| Andrew P Cooper Limited | Other services | 2018 |
| Andrews Estates Ltd | Real estate | 2025 |
| Andrius Sinkevicius Ltd | Transport & logistics | 2022 |
| Andwhy Studios Ltd | Information & communication | 2023 |
| Andygt Ltd | Transport & logistics | 2025 |
| Anecdotal Research Ltd | Professional & scientific | 2016 |
| Anemoia Labs Ltd | Information & communication | 2024 |
| Angel Business Solutions Limited | Real estate | 2003 |
| Angel Concierge Ltd | Wholesale & retail | 2023 |
| Angel Lane Hatter Street Management Company Ltd | Households | 2018 |
| Angela Payne Ltd | Professional & scientific | 2024 |
| Angels Cafe Ltd | Hospitality | 2013 |
| Angels Home Care & Community Services Ltd | Health & social care | 2023 |
| Angels Meal Ltd | Manufacturing | 2016 |
| Angels Property Holdings Ltd | Construction | 2021 |
| Angie's Fabulous Care Services Limited | Health & social care | 2016 |
| Angimec Limited | Administrative & support | 2026 |
| Angj Holdings Limited | Financial services | 2020 |
| Anglesey Energy Limited | Energy | 2019 |
| Anglia Camper Conversions Ltd | Wholesale & retail | 2018 |
| Anglia Hosting Limited | Information & communication | 2024 |
| Anglia Rendering & Facades Ltd | Construction | 2018 |
| Anglia Surface Care Limited | Administrative & support | 2010 |
| Anglian Artificial Grass Ltd | Administrative & support | 2016 |
| Anglian Earth Works Limited | Construction | 2015 |
| Anglo-Indonesian Investments Ltd | Professional & scientific | 2022 |
| Angus Wheat Consultants Limited | Agriculture & fishing | 2011 |
| Angus' Garden Solutions Ltd | Administrative & support | 2025 |
| Ania Film & Theatre Ltd | Professional & scientific | 2022 |
| Anica Consultancy Ltd | Information & communication | 2025 |
| Animal Aiders Limited | Wholesale & retail | 2006 |
| Animals First Group Ltd | Wholesale & retail | 2021 |
| Animalsphere Limited | Wholesale & retail | 2025 |
| Animalsware Ltd | Wholesale & retail | 2025 |
| Animated Digital Learning Limited | Information & communication | 2021 |
| Anime Universe Limited | Wholesale & retail | 2025 |
| Anita Benge Accountancy Services Limited | Extraterritorial | 2009 |
| Aniyota Limited | Information & communication | 2025 |
| Anjedorangi Ltd | Wholesale & retail | 2022 |
| Anjuna Group Limited | Financial services | 2025 |
| Anjuna West Limited | Hospitality | 2024 |
| Anki Properties Ltd | Real estate | 2017 |
| ANKOLET1 Ltd | Real estate | 2023 |