| Bedwell Park Estate Management Company Limited | Households | 2008 |
| Bedwell Park Leasehold Management Company Limited | Households | 2008 |
| Beech Tax and Accounts Limited | Professional & scientific | 2021 |
| Beechfield Electrical Ltd | Construction | 2019 |
| Beechwood Cloud Property Ltd | Real estate | 2019 |
| Beechwood Court (Knaphill) Limited | Households | 1978 |
| Beechwood View Estate Management Limited | Households | 2013 |
| Beehive Boutique Ltd | Other services | 2018 |
| Beer Festival Equipment & Events Ltd | Hospitality | 2024 |
| Beerlaroitech Ltd | Information & communication | 2022 |
| Beit Phevi-Esterael Property Ltd | Real estate | 2024 |
| Belko Contractors Ltd | Construction | 2007 |
| Belletech Services Limited | Professional & scientific | 2020 |
| Belloina Property Investment Ltd | Real estate | 2020 |
| Bells Engineering Limited | Extraterritorial | 1937 |
| Belswains Lane Residents Association Limited | Households | 2000 |
| Belvedere West Ltd | Real estate | 2022 |
| Belyi Consulting Limited | Professional & scientific | 2007 |
| BEN Balika Construction Ltd | Construction | 2023 |
| Benchleys Developments Limited | Construction | 2018 |
| Beneson Ltd | Professional & scientific | 2020 |
| Bennachie Associates Ltd | Professional & scientific | 2007 |
| Bennett Services Ltd | Construction | 2024 |
| Bennetts Barber Shop Ltd | Professional & scientific | 2019 |
| Benross Limited | Professional & scientific | 2000 |
| Bensons Financial Limited | Professional & scientific | 2014 |
| Bentall Place (Heybridge) Management Company Limited | Households | 2017 |
| Beorganised Limited | Administrative & support | 2023 |
| Berghoff UK Ltd | Wholesale & retail | 2013 |
| Bergon Architects Ltd | Professional & scientific | 2024 |
| Berkhamsted Construction Ltd | Construction | 2013 |
| Berkhamsted Heating Ltd | Construction | 2014 |
| Berkhamsted Home Designs Ltd | Construction | 2019 |
| Berkhamsted Interiors Limited | Other services | 2025 |
| Berkhamsted Ltd | Real estate | 2023 |
| Berkhamsted Motor Cycle and Car Club Limited | Arts & recreation | 1987 |
| Berko Limited | Wholesale & retail | 2025 |
| Berko Trader Ltd | Administrative & support | 2023 |
| Berrymart Ltd | Wholesale & retail | 2010 |
| Bert Harkins Racing Limited | Real estate | 1990 |
| Berwick Consulting Limited | Information & communication | 2011 |
| Besi Mobile Valeting Ltd | Administrative & support | 2026 |
| Bespoke Verse Limited | Arts & recreation | 2014 |
| Bespokegreen Table Company Limited | Other services | 2017 |
| Best Lane Chauffeurs Limited | Transport & logistics | 2025 |
| Best Rate Group Limited | Financial services | 2011 |
| Best Trans & Raptor Ltd | Financial services | 2012 |
| Best UK Management Ltd | Real estate | 2025 |
| Best Zone Traders Ltd | Wholesale & retail | 2024 |
| Bestobell Aviation Products Limited | Extraterritorial | 1909 |
| Bestobell Engineering Products Limited | Extraterritorial | 1954 |
| Bestobell Insulation Limited | Extraterritorial | 1967 |
| Bestobell Meterflow Limited | Extraterritorial | 1958 |
| Bestobell Mobrey Limited | Extraterritorial | 1934 |
| Bestobell Service Co. Limited | Extraterritorial | 1909 |
| Bestsaidbyu Community Interest Company | Health & social care | 2025 |
| Better Days Life Coaching Limited | Administrative & support | 2023 |
| Better Floor Ltd | Construction | 2022 |
| Better Homes Better Living Ltd | Real estate | 2019 |
| Better Managment Ltd | Hospitality | 2015 |
| Betty Plus Ltd | Wholesale & retail | 2018 |
| Beyond Boring Ltd | Professional & scientific | 2022 |
| Bezda Camanchi Ltd | Financial services | 2012 |
| Bezda Nash Care Group Ltd | Financial services | 2022 |
| BFJ Limited | Wholesale & retail | 2025 |
| BFL International Ltd | Administrative & support | 2025 |
| BGG Enterprises Ltd | Professional & scientific | 2026 |
| BH Tackley LLP | | 2017 |
| Bhavitha Limited | Information & communication | 2014 |
| Bhyb Limited | Hospitality | 2023 |
| Biatransworld Ltd | Transport & logistics | 2014 |
| Bibeekon Ltd | Construction | 2026 |
| Bibleway Churches UK (Worldwide) | Other services | 2009 |
| Bidford Gardens Management Company Limited | Households | 2016 |
| Bifrost Financial Management Services Limited | Professional & scientific | 2015 |
| Big and Small Property Services Limited | Transport & logistics | 2026 |
| Big and Small Services Ltd | Transport & logistics | 2021 |
| Big Juicy Burgers (Hemel) Ltd | Hospitality | 2025 |
| Big Juicy Burgers Ltd | Professional & scientific | 2024 |
| Big Juicy Burgers Watford Ltd | Hospitality | 2024 |
| Biggar Financial Planning Limited | Financial services | 2010 |
| Bikaina Global Limited | Transport & logistics | 2026 |
| Bill.Td Limited | Transport & logistics | 2015 |
| Billiongate Holdings Limited | Real estate | 2021 |
| Bimkel Limited | Health & social care | 2022 |
| Binder UK Limited | Wholesale & retail | 2009 |
| Binfield (Blue Mountain) Management Company Limited | Households | 2018 |
| BIO Cleanse UK Ltd | Administrative & support | 2025 |
| Biocoral (UK) Limited | Real estate | 2004 |
| Bipo Properties Ltd | Real estate | 2026 |
| Bircham Cardiac Physiology Services Limited | Other services | 2022 |
| Birchenall & Wilson Ltd | Administrative & support | 2018 |
| Birchgrove Marketing Ltd | Professional & scientific | 2016 |
| Bird Partnerships Ltd | Administrative & support | 2023 |
| Birdie Base Golf Ltd | Arts & recreation | 2025 |
| Birdsall Air Conditioning Ltd. | Construction | 1993 |
| Birdsall Decarbonisation Limited | Construction | 2024 |
| Birdsall Group Limited | Construction | 2006 |
| Birdsall Networks Limited | Construction | 1975 |
| Birdsall Technical Services Limited | Construction | 2025 |