| Barnes Elec Ltd | Construction | 2020 |
| Barnett Installation Services Limited | Other services | 2003 |
| Barrett and Sainty Investments Ltd | Financial services | 2017 |
| Barretts Bridge Leisure Buildings Limited | Other services | 1992 |
| Barrianne-Photos Limited | Information & communication | 2012 |
| Barrowden Designs Limited | Wholesale & retail | 2025 |
| Barton and Clark Limited | Construction | 2024 |
| Barwell Accountants Ltd | Professional & scientific | 2009 |
| Barwell Transport Limited | Agriculture & fishing | 2011 |
| Barwick Developments Limited | Real estate | 2015 |
| Basa (UK) Limited | Professional & scientific | 2006 |
| Baseline Paving Ltd | Construction | 2016 |
| Basil Cosy Homes Ltd | Real estate | 2024 |
| Bateman Farms Contracting Limited | Agriculture & fishing | 2013 |
| Bayco Ltd | Manufacturing | 2016 |
| Bayersan UK Ltd | Wholesale & retail | 2007 |
| Bayliss Hiab & Haulage Ltd | Transport & logistics | 2012 |
| BAZ Catering Ltd | Hospitality | 2017 |
| BB European Bulk Ltd | Transport & logistics | 2023 |
| BBB Testing Ltd | Construction | 2023 |
| BD Bookkeeping Solutions Limited | Professional & scientific | 2026 |
| BE Wise K9 Security Ltd | Other services | 2025 |
| Beaumont Independent Traders Ltd | Construction | 2019 |
| Beauty at ALL About YOU Limited | Other services | 2016 |
| BEH Future Energy Ltd | Wholesale & retail | 2025 |
| Beicore Ltd | Information & communication | 2010 |
| Bell Accountancy Services Limited | Professional & scientific | 2024 |
| Bella Bloom Hair Ltd | Other services | 2026 |
| Bennett Mews Residents Management Company Limited | Households | 2019 |
| Benweld Limited | Manufacturing | 2018 |
| Bev's Taxis Limited | Transport & logistics | 2026 |
| Bexwell Farm Limited | Wholesale & retail | 2022 |
| Beyond Beauty Aesthetics Limited | Other services | 2024 |
| Beyond Beauty Salon Limited | Other services | 2025 |
| BG Fast Food Limited | Hospitality | 2021 |
| BG Zakuski Ltd | Manufacturing | 2024 |
| Bialka Engineering Ltd | Manufacturing | 2022 |
| Big Char Services Ltd | Construction | 2019 |
| Big Tower City Limited | Wholesale & retail | 2025 |
| Big Wheels Training (UK) Ltd | Education | 2022 |
| Bike Shed Motorbikes Ltd | Wholesale & retail | 2019 |
| Billi Castro Snack Bar Restaurant 69 Limited | Hospitality | 2025 |
| Birch Close Management Company Ltd | Households | 2016 |
| Bissec Holdings Limited | Extraterritorial | 2018 |
| BIT Programmers Ltd | Information & communication | 2022 |
| BJ Tiller & SON Limited | Construction | 2017 |
| Bjulaseta Botanicals Ltd | Manufacturing | 2025 |
| BL4K Amusements Limited | Arts & recreation | 2020 |
| Black Cat Residential Property Limited | Real estate | 2014 |
| Blackberries Childcare (Corby) Limited | Education | 2023 |
| Blackberries Childcare (March) Limited | Education | 2015 |
| Blackberries Childcare (Peterborough) Limited | Education | 2012 |
| Blackberries Childcare Limited | Education | 2005 |
| Blackberries Holdings Limited | Financial services | 2022 |
| Blackbriar Cold Store Services Ltd | Construction | 2023 |
| Blackheath Stamps Ltd | Extraterritorial | 2021 |
| Bland Design Ltd | Manufacturing | 2019 |
| Blankmaster Ltd | Manufacturing | 2016 |
| Blaydon Properties Limited | Real estate | 2019 |
| BLB Harp Doctor Limited | Professional & scientific | 2008 |
| Blindscope Limited | Administrative & support | 2022 |
| Bliss Potatoes Limited | Wholesale & retail | 2026 |
| Blissful Fishery Ltd | Administrative & support | 2019 |
| Blissit Ltd | Information & communication | 2020 |
| Bloodline Collective Ltd | Arts & recreation | 2026 |
| Bloom & Wake Garage Ltd | Wholesale & retail | 2017 |
| Blue Door Lettings Limited | Real estate | 2018 |
| Blue Hole Ltd | Transport & logistics | 2021 |
| Blue Sky Home Build Limited | Agriculture & fishing | 2018 |
| Blue Zebra Talent Limited | Administrative & support | 2020 |
| Bluechip Brand Solutions Limited | Administrative & support | 2009 |
| Blyth Equipment Limited | Manufacturing | 2010 |
| Bodia Limited | Hospitality | 2018 |
| Bohdan Holdings Ltd | Financial services | 2020 |
| Boldero Trading Ltd | Wholesale & retail | 2006 |
| Bolis Ltd | Transport & logistics | 2018 |
| Bonded Construction Limited | Construction | 2026 |
| Bonneville Property Limited | Professional & scientific | 2008 |
| BOO & Harvey Ltd | Health & social care | 2017 |
| Bopadot Limited | Information & communication | 2010 |
| Boss & Beyond Ltd | Professional & scientific | 2019 |
| Boston Lake Ltd | Information & communication | 2020 |
| Boston Lettings Ltd | Real estate | 2025 |
| Boulder School Ltd | Education | 2025 |
| Bourne 2 Hire Commercials Limited | Professional & scientific | 2020 |
| Bourne 2 Hire Minibuses Limited | Administrative & support | 2023 |
| Bourne Carpets & Flooring Limited | Wholesale & retail | 2017 |
| Bowser Ollard & Bentley Limited | Professional & scientific | 2012 |
| Bowthorpe Hall Gardens Wisbech Management Limited | Administrative & support | 2000 |
| Box Mystery Ltd | Wholesale & retail | 2025 |
| Boxedit Storage Ltd | Transport & logistics | 2016 |
| Boxelu Ltd | Administrative & support | 2025 |
| Braccio Limited | Wholesale & retail | 2022 |
| Bramblebee Farm Butchery & Catering Services Limited | Manufacturing | 2018 |
| Bramblebee Farm Limited | Agriculture & fishing | 2013 |
| Brancaster Links Limited | Extraterritorial | 1998 |
| Brancaster Sand Limited | Extraterritorial | 2000 |
| Breechland 1965 Limited | Extraterritorial | 2014 |
| Brenchley Engineering Ltd | Professional & scientific | 2003 |
| Brenton Homes Ltd | Hospitality | 2023 |