| Arcelis Ltd | Construction | 2023 |
| Arch Construction (Norfolk) Ltd | Construction | 2020 |
| Archi-Vis Studio Limited | Professional & scientific | 2017 |
| Archimedes Engineering Ltd | Professional & scientific | 2019 |
| Archimedes Engineering Solutions Ltd | Professional & scientific | 2012 |
| Architrave Historical Services Limited | Professional & scientific | 2017 |
| Archro Properties Limited | Construction | 2022 |
| Arcitek Building Design Limited | Professional & scientific | 2017 |
| Arctic Virtual Limited | Information & communication | 2009 |
| Ardale Developments (Norfolk) Ltd | Construction | 2024 |
| Argyle Kitchens Ltd | Construction | 2024 |
| Aries Cladding Installations Limited | Administrative & support | 2018 |
| Arkville Limited | Real estate | 2021 |
| Arnold & Transport Ltd | Transport & logistics | 2025 |
| Arpo Global Limited | Wholesale & retail | 2013 |
| Arrow Roofing Limited | Construction | 2002 |
| ARS Property Development Ltd | Real estate | 2020 |
| Art Contact Limited | Arts & recreation | 1992 |
| Artemisia: Plant Medicine Pathways CIC | Education | 2022 |
| Artis Kitchens Ltd | Manufacturing | 2026 |
| Artisan Drinks Company Limited | Manufacturing | 2017 |
| Arts Business Services Ltd | Extraterritorial | 2026 |
| Arvy Ltd | Transport & logistics | 2018 |
| Aryian Ltd | Wholesale & retail | 2021 |
| AS Engineering Solutions 2016 Limited | Professional & scientific | 2016 |
| Ascend Competitions Ltd | Wholesale & retail | 2026 |
| ASH Grove Flats (Management) Limited | Real estate | 1998 |
| ASH Properties (Norfolk) Ltd | Real estate | 2021 |
| ASH Property Rentals Ltd | Real estate | 2025 |
| Ashby HR Limited | Professional & scientific | 2024 |
| Ashby Newton Limited | Professional & scientific | 2006 |
| Ashdown Fabrications Limited | Manufacturing | 2023 |
| Ashill Precision Engineering Ltd | Manufacturing | 2012 |
| Ashley Gardens (Old Hunstanton) RTM Limited | Real estate | 2010 |
| Ashrow Talent Management Ltd | Arts & recreation | 2015 |
| Ashwicken Farms LLP | | 2015 |
| Ashwicken Sporting LLP | | 2010 |
| Ashworth Property Holdings Limited | Real estate | 2024 |
| ASM Property (Cheshire) Limited | Real estate | 2025 |
| Aspire 51 Ltd | Professional & scientific | 2020 |
| Aspire Construction Safety Services Limited | Professional & scientific | 2006 |
| Asprey Management Solutions Limited | Information & communication | 2002 |
| Asset Management Associates (Europe) Limited | Extraterritorial | 2009 |
| Asset-Fix Ltd | Other services | 2022 |
| Assured Boiler Care Ltd | Construction | 2013 |
| AST Advisory Services Limited | Professional & scientific | 2025 |
| Astley Period Homes Limited | Construction | 1998 |
| Astrive Limited | Real estate | 2021 |
| Asylum Artists Ltd | Other services | 2023 |
| AT Publishing 2020 Ltd | Information & communication | 2021 |
| AT Services (Kings Lynn) Limited | Other services | 2020 |
| ATA & 3 Ltd | Wholesale & retail | 2025 |
| Atas 46 Limited | Hospitality | 2024 |
| Atech Property Management Limited | Real estate | 2018 |
| Atelier Associates Limited | Professional & scientific | 2015 |
| Athene Research & Consulting Limited | Professional & scientific | 2022 |
| Atlas Earthwork Services Limited | Construction | 2011 |
| Atlas Engineering Systems Ltd | Manufacturing | 2019 |
| ATP Auto Repair Limited | Wholesale & retail | 2024 |
| ATP Motors Limited | Wholesale & retail | 2024 |
| Attn 2 Detail Limited | Wholesale & retail | 2023 |
| Auracre Ltd | Real estate | 2022 |
| Aurex International (Europe) Ltd | Professional & scientific | 2018 |
| Authentica Risk Advisory Limited | Real estate | 2026 |
| Autoleys Limited | Wholesale & retail | 2015 |
| Automated Test Solutions Ltd | Professional & scientific | 2024 |
| Automis Ltd | Administrative & support | 2025 |
| Automotive Imports Ltd | Wholesale & retail | 2025 |
| AV Group Retail Ltd | Wholesale & retail | 2025 |
| Avant-Garde Studios Ltd | Professional & scientific | 2022 |
| Avanti Building Developments Ltd | Construction | 2025 |
| Avanti Doors Ltd | Manufacturing | 2020 |
| Avastatraya Ltd | Health & social care | 2018 |
| Aven Limited | Administrative & support | 2006 |
| Avenging Angels Ltd | Hospitality | 2026 |
| Aventis Engineering Group Limited | Professional & scientific | 2019 |
| Avenue House Owners Association Limited | Real estate | 1989 |
| AVN Arena Norfolk Limited | Professional & scientific | 2014 |
| Avocet Construction (Norfolk) Ltd | Construction | 2024 |
| Avocet Drive Management Company Limited | Households | 2021 |
| Avocet Homes (Developments) Limited | Construction | 2024 |
| Avocet Homes (Norfolk) Limited | Construction | 2020 |
| Avocet Homes Construction Ltd | Construction | 2025 |
| Avocet Kitchens Ltd | Manufacturing | 2024 |
| AVR (King's Lynn) Limited | Wholesale & retail | 2014 |
| Awakolture Limited | Health & social care | 2026 |
| AWB Distributions Ltd | Wholesale & retail | 2026 |
| AWE (Holdings) Limited | Real estate | 2021 |
| AWG Project Consulting Ltd | Professional & scientific | 2024 |
| AX Private Management Co. Limited | Households | 2023 |
| Aydon Holdings Ltd | Financial services | 2022 |
| Aydon Limited | Wholesale & retail | 2011 |
| Ayers and SON | Real estate | 1947 |
| Ayla Publishing Ltd | Information & communication | 2024 |
| Ayres Builders Limited | Construction | 2009 |
| B & B Engineering EOT Limited | Administrative & support | 2022 |
| B & I Enterprises Limited | Professional & scientific | 2019 |
| B & M Roofing & Cladding Ltd | Construction | 2017 |
| B & W Farms Limited | Agriculture & fishing | 1988 |
| B Durrant Groundworks Limited | Administrative & support | 2024 |