| Alterjective Limited | Professional & scientific | 2011 |
| Altunok Ltd | Other services | 2024 |
| Aluminium Boats East Coast Limited | Manufacturing | 2016 |
| AM to PM Services Ltd | Other services | 2023 |
| Amateur to Professional Limited | Transport & logistics | 2011 |
| Amber LET Ltd | Real estate | 2023 |
| Amber Motors Ltd | Wholesale & retail | 2024 |
| Amber&I Ltd | Wholesale & retail | 2025 |
| Amberley Grange (NO. 2) Management Company Limited | Households | 2007 |
| Amble UK Ltd | Health & social care | 2022 |
| Ambleside MGT Co Limited | Households | 2023 |
| AMC Property Management Ltd | Real estate | 2023 |
| Amerwin Limited | Construction | 2004 |
| Amgdeg Holding Ltd | Real estate | 2024 |
| Amigos Chinese Ltd | Hospitality | 2024 |
| Amikalauskas Ltd | Transport & logistics | 2023 |
| AMJ Interiors Ltd | Construction | 2023 |
| Amley Limited | Administrative & support | 2023 |
| Amold Ltd | Administrative & support | 2025 |
| AMR Electrical Services EOT Limited | Administrative & support | 2021 |
| AMR Electrical Services Limited | Construction | 2003 |
| AMR Fire & Security EOT Limited | Administrative & support | 2022 |
| AMR Fire & Security Ltd | Administrative & support | 2013 |
| AMR Group (Holdings) Limited | Financial services | 2016 |
| AMR Mechanical Services EOT Limited | Administrative & support | 2021 |
| AMR Mechanical Services Ltd | Professional & scientific | 2013 |
| Amthor Risk Partners Limited | Financial services | 2019 |
| AMW 2025 Ltd | Construction | 2025 |
| AN Arlesey Village Ltd | Wholesale & retail | 2014 |
| Anab Medical Services Ltd | Health & social care | 2025 |
| ANB Pine Furniture Limited | Wholesale & retail | 2003 |
| Anchorage Barn Equine Clinic Limited | Professional & scientific | 2010 |
| Anchorage Barn Veterinary Clinic Limited | Professional & scientific | 2011 |
| Ancient Barn Ltd | Administrative & support | 2002 |
| Anderson Shelter Productions Limited | Information & communication | 2014 |
| Andrea Scott Financial Services Ltd | Financial services | 2018 |
| Andrew Clarke Flooring Ltd | Construction | 2019 |
| Andrew Collison Limited | Arts & recreation | 2002 |
| Andrew J Bush Limited | Construction | 2007 |
| Andrew M Jarvis Limited | Manufacturing | 2013 |
| Andrew W Wright Ltd. | Administrative & support | 2010 |
| Andy Futter Limited | Construction | 2013 |
| Andy's Plastering Limited | Construction | 2020 |
| Anene Media Limited | Professional & scientific | 2025 |
| Angel Sandelson Design Ltd. | Professional & scientific | 2020 |
| Anglia Business Growth Consultants Limited | Professional & scientific | 1996 |
| Anglia Coaching Limited | Health & social care | 2014 |
| Anglia Electrical Wholesale Ltd | Wholesale & retail | 2010 |
| Anglia Landscapes Limited | Administrative & support | 2006 |
| Anglia Motorsport Developments Ltd | Manufacturing | 2018 |
| Anglia Paddocks Properties Limited | Construction | 2021 |
| Anglia Trees Ltd | Agriculture & fishing | 2022 |
| Anglian Accountancy Services Limited | Professional & scientific | 1999 |
| Anglian Carpentry Limited | Construction | 2014 |
| Anglian Confidential Data Services Limited | Water & waste | 2005 |
| Anglian Developers Limited | Construction | 2021 |
| Anglian Project Management (Services) Ltd | Construction | 1998 |
| Anglian Waste Solutions Ltd | Wholesale & retail | 2018 |
| Anglin Business Services Ltd | Professional & scientific | 2026 |
| Animals at Home (KL & WN) Limited | Professional & scientific | 2020 |
| Anmer Construction Limited | Construction | 2019 |
| Anmer Contracts Norfolk Ltd | Construction | 2019 |
| Anmer Properties Limited | Construction | 2019 |
| Anna Warren Hair Limited | Other services | 2015 |
| Answercontra Ltd | Wholesale & retail | 2025 |
| Anthony Edits Limited | Information & communication | 2016 |
| Anthracite Rose Limited | Manufacturing | 2021 |
| Anti Money Laundering Professionals Limited | Professional & scientific | 2009 |
| Antler & Moose Ltd | Wholesale & retail | 2023 |
| Anura Wellness Limited | Health & social care | 2026 |
| Anvil Engineering (Norfolk) Limited | Manufacturing | 2004 |
| Anza Financial Planning Limited | Professional & scientific | 2026 |
| AP Build & Drive Ltd | Construction | 2026 |
| AP SD Sixty SIX Limited | Wholesale & retail | 2025 |
| AP Studio Creative Ltd | Professional & scientific | 2025 |
| APB Site Engineering Ltd | Construction | 2016 |
| Apdc Vehicle Technician Ltd | Wholesale & retail | 2025 |
| Apex Agency Ltd | Administrative & support | 2017 |
| Apex Contracting Group Ltd | Construction | 2026 |
| Apex Energy Ltd | Energy | 2015 |
| Apex Logistics Norfolk Ltd | Transport & logistics | 2024 |
| Apgarcia Ltd | Health & social care | 2025 |
| APO Developments Ltd | Real estate | 2026 |
| Applepik Events Ltd | Other services | 2017 |
| Appleton and Flowers Limited | Construction | 2005 |
| APS Projects Ltd | Construction | 1991 |
| APT Surfacing Ltd | Construction | 2025 |
| Aqsi Limited | Households | 2025 |
| Aqua Deluxe Limited | Wholesale & retail | 2022 |
| Aqua Devine Limited | Administrative & support | 2020 |
| Aqualec Limited | Construction | 2025 |
| Aqualeo 2004 Limited | Real estate | 2021 |
| AR Consulting East Anglia Ltd | Administrative & support | 2019 |
| ARC Estates (Norfolk) Limited | Real estate | 2024 |
| ARC Fabrications (King's Lynn) Limited | Manufacturing | 1993 |
| ARC Fabrications Maintenance Ltd | Professional & scientific | 2017 |
| ARC Fabrications Projects Limited | Professional & scientific | 2004 |
| ARC Integrated Systems Ltd | Administrative & support | 2009 |
| ARC Sportswear Limited | Wholesale & retail | 2023 |
| Arcea Holdings Limited | Financial services | 2025 |