| Arcare Limited | Professional & scientific | 1999 |
| Archvale Developments Limited | Real estate | 2025 |
| Arlana Limited | Hospitality | 2000 |
| Armada Surveys Limited | Professional & scientific | 2001 |
| Arnold Marsh Ltd | Hospitality | 2020 |
| Artius Solutions Ltd | Professional & scientific | 2021 |
| ASC Psychology Limited | Education | 2017 |
| Ashbourne House Management Company Limited | Administrative & support | 2004 |
| Ashley Smith Engineering Services Ltd | Professional & scientific | 2017 |
| Asimakis Ltd | Professional & scientific | 2021 |
| ASK SAS Solutions Ltd | Professional & scientific | 2019 |
| ASL Wholesale Limited | Wholesale & retail | 2020 |
| Aspiration Developments Limited | Extraterritorial | 2019 |
| Aspiration Fire Protection Limited | Extraterritorial | 2019 |
| Aston Chase Psychology Services Ltd | Health & social care | 2010 |
| Asyli Limited | Wholesale & retail | 2025 |
| Atalanta Management Limited | Financial services | 2014 |
| Atlantis Software (East Anglia) Ltd | Information & communication | 2002 |
| Aubrey Burrows & Associates Ltd | Professional & scientific | 2005 |
| Audit and Training Limited | Professional & scientific | 2012 |
| Autoflow Packaging Limited | Administrative & support | 1999 |
| Avani Solutions Limited | Professional & scientific | 2012 |
| Aventurine Healing Ltd | Health & social care | 2014 |
| Axiom Control Equipment Limited | Manufacturing | 2017 |
| Azur LUX Real Estate Ltd | Real estate | 2026 |
| B & W Equine Group Limited | Professional & scientific | 2008 |
| B&M Cleaning Limited | Administrative & support | 2025 |
| Bacon Developments Ltd | Construction | 2022 |
| Bacons Enterprise Ltd | Agriculture & fishing | 2025 |
| Baddeley Farms Limited | Agriculture & fishing | 1962 |
| Badger Associates Limited | Administrative & support | 2001 |
| Balbedie Limited | Households | 1999 |
| Baleus Ltd | Professional & scientific | 2011 |
| Barkers Plumbing & Heating Limited | Construction | 2010 |
| Barley Marketing Ltd | Professional & scientific | 2025 |
| Barnards Heating Solutions Ltd | Construction | 2019 |
| Barric Holdings Limited | Manufacturing | 2025 |
| Barric Limited | Manufacturing | 2001 |
| Barry Clarke & SON (Haulage) Ltd. | Transport & logistics | 2011 |
| Bateson Consulting Limited | Manufacturing | 2001 |
| BAX Viiv Ltd | Wholesale & retail | 2018 |
| BB Transport (East Anglia) Limited | Transport & logistics | 2010 |
| Bdrsyndicates LLP | | 2020 |
| Beaird Electrical Engineering Ltd | Construction | 2023 |
| Bearsoul Wellbeing Limited | Other services | 2019 |
| Beauty & Wellness @Halfmoonsalon Ltd | Other services | 2025 |
| Beckford & Lewis Financial Planning Ltd | Financial services | 2019 |
| Becky Howe Consulting Limited | Professional & scientific | 2014 |
| Bedfield Development Limited | Construction | 2021 |
| Bedmed Ltd | Manufacturing | 2018 |
| BEE Paraplanning Services Ltd | Administrative & support | 2023 |
| Beech Croft (South Lopham) Management Company Limited | Households | 2009 |
| Beechtree Barns Management Limited | Households | 2005 |
| Beechwood Business Consultancy Limited | Administrative & support | 2007 |
| Bees of Diss Ltd | Wholesale & retail | 2020 |
| Beeson Developments Ltd | Construction | 2024 |
| Bekays DIY & Hardware Limited | Wholesale & retail | 2019 |
| Bekstar Limited | Administrative & support | 2000 |
| Belcher Engineering Limited | Manufacturing | 1978 |
| Benchmark Construction Management Limited | Construction | 2022 |
| Benini & Pearl Homes Ltd | Construction | 2025 |
| Bernard Tatum & SON Ltd | Construction | 2014 |
| BF1 Motorsport Holdings Limited | Professional & scientific | 1999 |
| BF1 Solutions Limited | Financial services | 2018 |
| BF1 Technologies Limited | Financial services | 2016 |
| BF1ELECTRONICS Limited | Professional & scientific | 2010 |
| BF1SYSTEMS Limited | Manufacturing | 1994 |
| Bgfc Services Ltd | Information & communication | 2014 |
| Bierton and Woods Ltd | Manufacturing | 2015 |
| Big House Holiday Rentals Limited | Administrative & support | 2007 |
| Big House Management Limited | Hospitality | 2016 |
| Big Sky Acoustics Ltd | Professional & scientific | 2011 |
| Black and White Group Limited | Administrative & support | 2016 |
| Black Dog Cyber Ltd | Information & communication | 2018 |
| Black Dog Outdoor Limited | Wholesale & retail | 2021 |
| Black Dog Vapes Ltd | Wholesale & retail | 2023 |
| Black Jacque Services Ltd | Wholesale & retail | 2017 |
| Black Light Onslaught Films Ltd | Information & communication | 2020 |
| Blackshorefishcompany Ltd | Wholesale & retail | 2023 |
| Blake's World Limited | Arts & recreation | 2016 |
| Blands Farm Close Management Company Limited | Households | 2006 |
| Blast Power Services Limited | Manufacturing | 1986 |
| BLC FAB Ltd | Hospitality | 2025 |
| Bletchley Tech Services Ltd | Construction | 2023 |
| Blewets Timber Ltd | Wholesale & retail | 2016 |
| BLM Holdings Ltd | Administrative & support | 2020 |
| Blue Side UP Ltd | Transport & logistics | 2022 |
| BMS Victoria Ltd | Hospitality | 2019 |
| Bodo Limited | Manufacturing | 2000 |
| Bodypak Group Ltd | Financial services | 2021 |
| Bodypak Limited | Manufacturing | 2008 |
| Borehole Services Ltd | Construction | 2015 |
| BOS Wiring Ltd | Manufacturing | 2019 |
| Bosprop Limited | Real estate | 2023 |
| Boss Barbers 36E Ltd | Other services | 2026 |
| Boss Cutz Ltd | Other services | 2023 |
| Brad Webb Limited | Agriculture & fishing | 2024 |
| Brancross Marketing Limited | Other services | 2005 |
| Brand Number 17 Ltd | Wholesale & retail | 2020 |
| Brandfluence Agency Ltd | Information & communication | 2023 |