| Baileywood Financial Planning Ltd | Financial services | 2014 |
| Balfin Consulting Ltd | Professional & scientific | 2024 |
| Balmers Care Farm CIC | Education | 2024 |
| Balthazar Engineering Limited | Information & communication | 2021 |
| Baracuda 2 Cafe Limited | Hospitality | 2008 |
| Bare Metal Software Limited | Information & communication | 2019 |
| Barista Life Limited | Manufacturing | 2017 |
| Barley View Properties Limited | Real estate | 2021 |
| Barrington Pubs Ltd | Hospitality | 2017 |
| Barsport Motors Ltd | Wholesale & retail | 2023 |
| Barton Inns Limited | Hospitality | 2023 |
| BAS Accountants Ltd | Professional & scientific | 2016 |
| Baterfive Ltd | Real estate | 2019 |
| Bates Boatyard Limited | Manufacturing | 2012 |
| Battram Associates Ltd | Professional & scientific | 2022 |
| Batucada Limited | Professional & scientific | 2021 |
| Bauen Associates Ltd | Construction | 2023 |
| Bauer Consulting Ltd | Professional & scientific | 2025 |
| BCA Supply Chain Ltd | Professional & scientific | 2016 |
| Bcloud Consultancy Ltd | Information & communication | 2019 |
| Bdiacov Ltd | Professional & scientific | 2025 |
| BE Fluent Ltd | Education | 2020 |
| Beacon Project Consultants Limited | Professional & scientific | 2019 |
| Beacon Surveying Services Limited | Professional & scientific | 2018 |
| Beacon View Homes Ltd | Construction | 2022 |
| Beans N Brunch Ltd | Hospitality | 2024 |
| Bear Catering Ltd | Hospitality | 2023 |
| Bearing 21 Limited | Professional & scientific | 2020 |
| Beatrice&Sons Limited | Hospitality | 2021 |
| Beau & Blake Limited | Households | 2024 |
| Bebe Enterprises Ltd | Health & social care | 2014 |
| Beeches Capital | Financial services | 2009 |
| Beeches Property (Tring) Ltd | Construction | 2011 |
| Belbeck Projects Limited | Construction | 2012 |
| Bell Rose Productions Limited | Information & communication | 2025 |
| Bellaflow Ltd | Information & communication | 2024 |
| BEN Heys Consulting Ltd | Information & communication | 2023 |
| BEN Jones Commercial Management Limited | Professional & scientific | 2024 |
| BEN Rood IT Ltd | Information & communication | 2018 |
| BEN Yates Ltd | Extraterritorial | 2009 |
| Benchmark Accountants Limited | Professional & scientific | 2017 |
| Berkhamsted Building Services Ltd | Construction | 1999 |
| Bermingham Project Management Services Ltd | Information & communication | 2014 |
| Berryfield Lodge Limited | Professional & scientific | 2017 |
| Berryfields Estates Limited | Extraterritorial | 2017 |
| Berryfields Lettings Limited | Extraterritorial | 2017 |
| Beta Bugs Limited | Professional & scientific | 2017 |
| Bettafaye Consulting Limited | Information & communication | 2024 |
| Bevan Carpentry & Construction Limited | Manufacturing | 2023 |
| Bevangrace Limited | Construction | 1985 |
| Beynerd Labs Ltd | Information & communication | 2024 |
| Big Dog Software Ltd | Information & communication | 2019 |
| Big Wood Burns Ltd | Manufacturing | 2021 |
| Bigkick! Creations Ltd. | Arts & recreation | 1999 |
| Biodigicine Technology Ltd | Information & communication | 2023 |
| Biotech Strategies Ltd | Professional & scientific | 2024 |
| Birdies & Bullseyes Ltd | Arts & recreation | 2025 |
| Bison Fit OUT Ltd | Construction | 2025 |
| Black Canvas Ltd | Information & communication | 2013 |
| Black Swan Strategy Ltd | Professional & scientific | 2023 |
| Blackboard Films Limited | Information & communication | 2017 |
| Blackdot Group Ltd | Financial services | 2025 |
| Blaxley Properties Ltd | Financial services | 2023 |
| Blaze Flares Ltd | Information & communication | 2019 |
| Blindside FX Ltd | Information & communication | 2025 |
| Blink Ripple Limited | Information & communication | 2023 |
| Bloom With Bella Ltd | Health & social care | 2024 |
| Blooming Bricks Ltd | Real estate | 2019 |
| Blooming Pixel Ltd | Information & communication | 2018 |
| Blue Associates Sportswear Limited | Manufacturing | 2018 |
| Blue Griffin Consultancy Ltd | Professional & scientific | 2018 |
| Blue Horizon Investment Solutions Limited | Professional & scientific | 2024 |
| Blue JAY Learning Ltd | Professional & scientific | 2020 |
| BM (Tring) Limited | Other services | 2017 |
| Boarscroft Management Limited | Households | 1995 |
| BOB Hawkes Projects Ltd | Information & communication | 2020 |
| Bold Horizons Limited | Education | 2017 |
| Bold Tracks Limited | Professional & scientific | 2021 |
| Bomobo Software Limited | Information & communication | 2016 |
| Bonhoga Capital Ltd | Transport & logistics | 2020 |
| BOOKM8 Ltd | Information & communication | 2025 |
| Booster Films Ltd | Information & communication | 2026 |
| Boots and Bark Ltd | Arts & recreation | 2021 |
| Bootstrap Finance Limited | Financial services | 2025 |
| Bootstrap Homes Limited | Construction | 2024 |
| Borland Tech Limited | Information & communication | 2017 |
| Boss Plant Sales Limited | Wholesale & retail | 2012 |
| Bossy's Bibs Limited | Wholesale & retail | 2016 |
| Bramingham Building and Electrical Services Limited | Construction | 2015 |
| Bramley Fairstead Ltd | Hospitality | 2010 |
| Bramley Precision Aerospace Ltd | Manufacturing | 2026 |
| Brayhaven Limited | Construction | 1997 |
| Brcomm Ltd | Administrative & support | 2022 |
| Breachwood Builders Ltd | Construction | 2014 |
| Breathe Print Management Limited | Administrative & support | 2012 |
| Breners of London Limited | Wholesale & retail | 2024 |
| Brian Brady Development Services Ltd | Construction | 2020 |
| Brian Clark Opticians Limited | Administrative & support | 2008 |
| Brian Evans Associates Ltd | Professional & scientific | 1999 |
| Bright Transformations Ltd | Professional & scientific | 2012 |