| AW Driver Training Limited | Education | 2025 |
| AW Fire & Electrical Ltd | Public administration | 2021 |
| Aweson Prints Limited | Other services | 2019 |
| AWT Ventures Limited | Wholesale & retail | 2026 |
| AX Build Ltd | Construction | 2019 |
| Axiom Construction (Cambs) Limited | Construction | 2022 |
| Axiom Construction Limited | Construction | 2015 |
| Axix Ltd | Information & communication | 2023 |
| AYA Property Investments Ltd | Real estate | 2025 |
| Ayaz&Asya Limited | Hospitality | 2023 |
| Ayers Tree Services Ltd | Agriculture & fishing | 2013 |
| B & B Carpentry Limited | Construction | 2003 |
| B & T Motors Limited | Wholesale & retail | 2009 |
| B AU Cube Limited | Professional & scientific | 2021 |
| B C Electrical Services Limited | Construction | 2019 |
| B Carter Developments Ltd | Construction | 2023 |
| B Carter Properties Ltd | Real estate | 2025 |
| B Murray Accountants and Financial Planning Consultants Limited | Financial services | 2015 |
| B S V Construction Services Limited | Construction | 1996 |
| B&N ELY Hand Car Wash Ltd | Administrative & support | 2024 |
| B. Sweeney Groundworks Ltd | Construction | 2010 |
| B.E.C. Rentals Ltd | Real estate | 2024 |
| Back on Track Injury Clinic Limited | Other services | 2016 |
| Balti-Morish Ltd | Wholesale & retail | 2025 |
| Bangla V Cuisine Limited | Hospitality | 2023 |
| Barak Catering Ltd | Hospitality | 2025 |
| Barbell Computing Ltd | Wholesale & retail | 2023 |
| Barcham Farms Limited | Agriculture & fishing | 1957 |
| Barcham Trees PLC | Agriculture & fishing | 1994 |
| Barclan Holdings Limited | Real estate | 2023 |
| Bargate Master Locksmith Limited | Other services | 2015 |
| Barnes Thompson Limited | Professional & scientific | 2002 |
| Barrelet Holdings Ltd | Households | 2025 |
| Barriercoat Ltd | Construction | 2018 |
| Bartkus Composites Limited | Manufacturing | 2020 |
| Bartram Express Limited | Information & communication | 2006 |
| Baudy OIL & GAS Lubricants and Services Ltd | Administrative & support | 2011 |
| BC BIO Ltd | Professional & scientific | 2012 |
| BC Drilling Services Limited | Construction | 2022 |
| BCE Consultants Limited | Professional & scientific | 2011 |
| Bdeb Patchwork Ltd | Other services | 2013 |
| BDN Building Developments Ltd | Construction | 2021 |
| BE Original United Ltd | Wholesale & retail | 2020 |
| Beach Plumbing and Heating Limited | Construction | 2018 |
| Beacon Precision Medicine Solutions Ltd | Professional & scientific | 2024 |
| Beamstation Technologies Limited | Professional & scientific | 2024 |
| Bearded Creative Limited | Professional & scientific | 2015 |
| Beau Urban Design Ltd | Professional & scientific | 2022 |
| Beauty by Evolution Limited | Wholesale & retail | 2016 |
| Beckett Gamble Properties Ltd | Real estate | 2025 |
| Becky Frewin Limited | Education | 2016 |
| Bedford Nominees NO. 75 Ltd | Professional & scientific | 1979 |
| BEE YOU Ltd | Education | 2024 |
| Beebizco Limited | Wholesale & retail | 2014 |
| Beeby Consultancy Limited | Administrative & support | 2012 |
| Beetroot Holding Ltd | Financial services | 2022 |
| Behaviour Change Consultants Ltd | Professional & scientific | 2021 |
| Bellairs Management Limited | Households | 2006 |
| Bellariva Clinic Ltd | Health & social care | 2026 |
| Bellavuebrands Limited | Manufacturing | 2024 |
| BEN Layn Builders Ltd | Construction | 2012 |
| BEN Warren Construction Limited | Construction | 2019 |
| Ben's Yard Cafes Ltd | Hospitality | 2022 |
| Ben's Yard Limited | Real estate | 2021 |
| Benchmark Roofing Ltd | Construction | 2015 |
| Benson Slater Ltd | Transport & logistics | 2022 |
| Bent & Cornwell Quality Meats Limited | Wholesale & retail | 2012 |
| Benton (ELY) Limited | Wholesale & retail | 2016 |
| Benwell Brickwork Limited | Construction | 2024 |
| Bernie Bookkeeping Service Ltd | Professional & scientific | 2017 |
| Berristead Ltd | Information & communication | 2011 |
| BES 1992 Limited | Real estate | 1992 |
| BES 1993 Limited | Real estate | 1993 |
| Bespoke Art Services Ltd | Arts & recreation | 2021 |
| Bespoke Builds (EC) Limited | Manufacturing | 2026 |
| Bessingham Manor Events Ltd | Hospitality | 2002 |
| Best Fit Dynamics Ltd | Information & communication | 2025 |
| Best Food ELY Ltd | Hospitality | 2026 |
| Bethany Robyn Limited | Administrative & support | 2014 |
| Beva Enterprises Limited | Other services | 1998 |
| Beva Limited | Other services | 2010 |
| Beyaz UN Ltd | Hospitality | 2019 |
| BG Barbers Ltd | Other services | 2025 |
| BGC Consulting Limited | Information & communication | 2011 |
| BGG Entertainment Limited | Hospitality | 2015 |
| Big Sky Venue Ltd | Hospitality | 2022 |
| Bilbel Ltd | Real estate | 2020 |
| Billys Hair Ltd | Other services | 2019 |
| Binary FEN Ltd | Information & communication | 2014 |
| Binderly Limited | Wholesale & retail | 2023 |
| Biofinance Solutions Limited | Professional & scientific | 2026 |
| Biologix Laboratories Limited | Manufacturing | 2002 |
| Biomass Future Generation Limited | Energy | 2010 |
| Biomethane (Castle Eaton) Limited | Energy | 2015 |
| Biomim Ltd | Professional & scientific | 2019 |
| Bionology Consulting Limited | Information & communication | 2025 |
| Birchcroft RTM Company Limited | Households | 2022 |
| Bird Proofing Ltd | Construction | 2024 |
| Bishop Plumbing Limited | Construction | 2025 |
| Bishops Walk (ELY) Management Company Limited | Households | 1995 |