| Alpha Cygni Investment Management Ltd | Financial services | 2020 |
| Alpha Electrical (Eastern) Limited | Construction | 2008 |
| Alpha Inclusion Limited | Education | 2014 |
| Alpha Medical Clinic Ltd | Health & social care | 2023 |
| Alpha Property Portfolio Limited | Real estate | 2016 |
| Alpha Quality Services Ltd | Professional & scientific | 2021 |
| Alpha SEC Labs Limited | Information & communication | 2026 |
| Alpha Sheetmetal & Ductwork Services Limited | Manufacturing | 1999 |
| ALPHA1MACHINERY Limited | Professional & scientific | 2018 |
| Alphega Design & Construction Management Limited | Professional & scientific | 2003 |
| Alpineglow Limited | Real estate | 1982 |
| Alpington Community Shop CIC | Wholesale & retail | 2025 |
| Alqea Limited | Professional & scientific | 2025 |
| ALS Solutions Limited | Wholesale & retail | 2025 |
| Alsheridan Limited | Information & communication | 2018 |
| Alston + Partners Limited | Professional & scientific | 2019 |
| Alston Farms Limited | Agriculture & fishing | 2002 |
| ALT Education Services Ltd | Education | 2018 |
| ALT Sports Limited | Wholesale & retail | 2021 |
| Altair Astro Limited | Professional & scientific | 2004 |
| Altay Transport Limited | Transport & logistics | 2025 |
| Altec Web Solutions Ltd | Information & communication | 2017 |
| Alterations Plus Limited | Other services | 2018 |
| Alternate Energies Limited | Energy | 2011 |
| Alti Bolaq Carpets Limited | Wholesale & retail | 2004 |
| Altitube Scaffolding (EA) Ltd | Construction | 2003 |
| Altitude Select Limited | Administrative & support | 2010 |
| Aluminox Holdings Ltd | Financial services | 2025 |
| Aluminox Ltd. | Wholesale & retail | 2014 |
| Alumni Design Ltd | Information & communication | 2017 |
| Alvea | Financial services | 2020 |
| Alvie Consulting Limited | Professional & scientific | 2022 |
| ALW Development Limited | Construction | 2023 |
| ALW Inspection Ltd | Professional & scientific | 2019 |
| Always Connect Ltd | Professional & scientific | 2022 |
| Always Smart Limited | Wholesale & retail | 2025 |
| ALX Construction (EA) Ltd | Construction | 2026 |
| Alysa Limited | Wholesale & retail | 2021 |
| AM Car Sales ( Norwich ) Ltd | Wholesale & retail | 2026 |
| AM Dermatology Services Ltd | Health & social care | 2023 |
| AM Property Solutions (Anglia) Ltd | Real estate | 2024 |
| Amaan Super Market Ltd | Wholesale & retail | 2021 |
| Amac Group Ltd | Professional & scientific | 2018 |
| Amader Property Limited | Real estate | 2021 |
| Amaly Cares Limited | Administrative & support | 2025 |
| Amaly Plus Ltd | Wholesale & retail | 2024 |
| Aman International Ltd | Wholesale & retail | 2016 |
| Amanda Nolan School of Performing Arts Ltd | Arts & recreation | 2018 |
| Amanuel Y Ltd | Wholesale & retail | 2025 |
| Amara Dream Properties Ltd | Real estate | 2020 |
| Amarela Group Ltd | Professional & scientific | 2023 |
| Amarozo Group Ltd | Other services | 2026 |
| Amati UK Limited | Professional & scientific | 2005 |
| Amazing BIO Cleaning Limited | Administrative & support | 2017 |
| Amazing Glazing Home Improvements Norwich Limited | Construction | 2013 |
| Amazing Health Limited | Wholesale & retail | 2005 |
| Amazon Associates Ltd | Construction | 2007 |
| Ambassador Sourcing Limited | Wholesale & retail | 2015 |
| Amber Bear Limited | Professional & scientific | 2019 |
| Amber DEW Business Services Ltd | Professional & scientific | 2024 |
| Amber Properties (EA) Ltd | Real estate | 2021 |
| Amber Radio Group Ltd | Information & communication | 2022 |
| Amber Radio Ltd | Information & communication | 2020 |
| Amber Spice Limited | Hospitality | 2018 |
| Amber Valley Norse Limited | Water & waste | 2020 |
| Amber's Bell Tent Camping Limited | Administrative & support | 2017 |
| Ambertech Services Ltd | Manufacturing | 2024 |
| Amberwhite Limited | Manufacturing | 2002 |
| Ambessa Play Limited | Manufacturing | 2020 |
| Ambicloud Ltd | Information & communication | 2021 |
| Ambience Lighting Limited | Wholesale & retail | 2017 |
| Ambition Public Relations Limited | Professional & scientific | 2019 |
| Amborna Properties Limited | Real estate | 2020 |
| Ambresbury Consulting Limited | Professional & scientific | 2025 |
| Ambrosas Limited | Professional & scientific | 2024 |
| Ambrose Homes (East Anglia) Ltd | Construction | 2003 |
| Ambry Foods Limited | Manufacturing | 2022 |
| AMC Health Ltd | Health & social care | 2025 |
| AMC Metalcraft Limited | Manufacturing | 2022 |
| AMC Transport Services Ltd | Professional & scientific | 2022 |
| AMD Retail Limited | Wholesale & retail | 2017 |
| AMD Waterproofing Ltd | Construction | 2019 |
| Amdas Management Limited | Professional & scientific | 2016 |
| Amdeepcha Limited | Wholesale & retail | 2008 |
| Amdeepcha Properties Limited | Real estate | 2013 |
| Amdega Limited | Extraterritorial | 2024 |
| Amder Computer Services Limited | Information & communication | 1997 |
| Amderley Books Limited | Arts & recreation | 2015 |
| Ameens Estates Ltd | Real estate | 2019 |
| Amelia’S Bar and Kitchen Ltd | Hospitality | 2024 |
| Amelie Flammekueche Restaurants Ltd | Hospitality | 2004 |
| Amelior Limited | Information & communication | 2013 |
| American Way Slush Limited | Wholesale & retail | 2022 |
| Ames Air Conditioning Limited | Construction | 1999 |
| Ames Associates LLP | | 2020 |
| Ameskyno Limited | Health & social care | 2022 |
| Amesworks Limited | Financial services | 2026 |
| Amethyst Clinical Education Ltd | Administrative & support | 2023 |
| Amethyst GI Ltd | Transport & logistics | 2019 |
| Amgl Limited | Other services | 2013 |