| BH Property Group (SW) Limited | Real estate | 2025 |
| Biddick Breaking and Pre-Training Limited | Arts & recreation | 2018 |
| Bilbord Media Ltd | Information & communication | 2024 |
| Bill Butters Windows Holdings Ltd | Financial services | 2026 |
| Bill Butters Windows Limited | Construction | 2002 |
| Billybot Ltd | Information & communication | 2026 |
| Bing Pharm Services Limited | Health & social care | 2018 |
| Binkind Ltd | Administrative & support | 2025 |
| Biryannie Ltd | Wholesale & retail | 2024 |
| Bishopbrook House Management Limited | Real estate | 2014 |
| BL Business Management Limited | Financial services | 2024 |
| Bl,Est Life:Style Limited | Manufacturing | 2004 |
| Black Sheep Cottages Limited | Real estate | 2022 |
| Black Spider Ltd | Professional & scientific | 2019 |
| Blackdown Management Company Limited | Households | 1984 |
| Blackdown Planning Partnership Ltd. | Extraterritorial | 2018 |
| Blackdown Surveys Ltd | Professional & scientific | 2023 |
| Blackford Investments Ltd | Real estate | 2023 |
| Blackford Projects Ltd | Professional & scientific | 2025 |
| Blackmore Vale DRY Lining Ltd | Construction | 2015 |
| Blackmores Machinery Haulage Limited | Transport & logistics | 2002 |
| Blade Barber 1 Ltd | Other services | 2026 |
| Blade Barber Yeovil Ltd | Other services | 2019 |
| Blade Publications Limited | Professional & scientific | 2012 |
| Blain Construction Ltd | Construction | 2022 |
| Blake Envelopes Holdings Limited | Financial services | 2024 |
| Blake Envelopes International Ltd | Financial services | 2007 |
| Blake Managed Services Limited | Administrative & support | 2018 |
| Blancrock Limited | Professional & scientific | 2010 |
| Blatnoi Company Ltd | Wholesale & retail | 2016 |
| Blaybridge Limited | Agriculture & fishing | 1991 |
| Bliss Trading Limited | Wholesale & retail | 2006 |
| Blooming BEE Hub Ltd | Hospitality | 2025 |
| Blossom Creative Ltd | Professional & scientific | 2024 |
| Bltft Care Partners Limited | Health & social care | 2026 |
| Bltft Properties Limited | Real estate | 2026 |
| Blue Bentley Limited | Transport & logistics | 2022 |
| Blue Eden Group Limited | Wholesale & retail | 2015 |
| Blue FOX Wealth Management Limited | Financial services | 2014 |
| Blue Sunrise Care Limited | Health & social care | 2016 |
| Blueloop Limited | Information & communication | 2000 |
| BM Gunn Limited | Real estate | 2001 |
| BMB Fitness Limited | Arts & recreation | 2023 |
| Bmlk Limited | Health & social care | 2022 |
| Board Family Partnership Ltd | Agriculture & fishing | 2018 |
| Boarder Landscapes Ltd | Construction | 2022 |
| Boba and Dessert Limited | Hospitality | 2024 |
| Boba Ebong Dessert Ltd | Hospitality | 2026 |
| Bobs Cars Dorchester Limited | Extraterritorial | 2018 |
| Bolt Financial Services Ltd | Financial services | 2023 |
| Boltsburn Property Management Limited | Real estate | 2025 |
| Bond Holdings (Somerset) Ltd | Real estate | 2020 |
| Bookmyrecovery.Com Ltd | Transport & logistics | 2025 |
| Boon Brown Limited | Professional & scientific | 1996 |
| Boss-Line Bullyz Official Ltd | Agriculture & fishing | 2025 |
| Botanical Values Limited | Arts & recreation | 2025 |
| Botley Bess Ltd | Financial services | 2022 |
| Botley Energy Reserve Limited | Construction | 2018 |
| Bournemouth Bedding Centres Limited | Wholesale & retail | 1989 |
| Bowshers' Electrical Services Limited | Construction | 1972 |
| Bptl 2026 Limited | Financial services | 2018 |
| Bradfords Building Supplies Limited | Wholesale & retail | 1933 |
| Bradfords Timber Supplies Limited | Professional & scientific | 2010 |
| Bram Stoker Estate Limited | Administrative & support | 2025 |
| Brand & Co (Booksellers) Ltd | Wholesale & retail | 1990 |
| Briars Farm Limited | Agriculture & fishing | 2014 |
| Brice Holdings Limited | Real estate | 2020 |
| Brice Property Lettings Ltd | Real estate | 2020 |
| Bridge Farm Cider Limited | Manufacturing | 2011 |
| Bridge Global Energy Limited | Wholesale & retail | 2025 |
| Bright Tree Strategies Ltd | Professional & scientific | 2025 |
| Brimley Associates Limited | Wholesale & retail | 2008 |
| Brimsmore IT Ltd | Information & communication | 2017 |
| Brinell Limited | Professional & scientific | 2024 |
| Bristow Reproduction Furniture Limited | Wholesale & retail | 1998 |
| Britannia GAS & Heating Limited | Construction | 2012 |
| Britten Farming Ltd | Real estate | 2025 |
| Brivalton Ltd | Professional & scientific | 2022 |
| Broadleaze Farm Enterprises Limited | Agriculture & fishing | 1986 |
| Brockham Property Ltd | Construction | 2019 |
| Bromfield Homes Ltd | Real estate | 2021 |
| Bromley Enterprise Limited | Transport & logistics | 2019 |
| Brookson (5278C) Limited | Administrative & support | 2007 |
| Bruce Soord Ltd | Information & communication | 2023 |
| Brue Farms Limited | Agriculture & fishing | 2014 |
| Brunel Place (Martock) Limited | Households | 2006 |
| Bryan Goss Limited | Wholesale & retail | 1971 |
| BSA PUB Group Limited | Hospitality | 2017 |
| BSH Aves Properties Ltd | Real estate | 2023 |
| Bsmg Fremont Healthcare Ltd | Health & social care | 2026 |
| Buckland Farms Limited | Agriculture & fishing | 1952 |
| Bugler Properties Limited | Financial services | 2019 |
| Bullet's Sports Bar Ltd | Arts & recreation | 2020 |
| Bunsmiths Ltd | Hospitality | 2015 |
| Burch (SW) Limited | Construction | 2023 |
| Burden & Best Roofing Limited | Construction | 2003 |
| Burgertogo Ltd | Hospitality | 2023 |
| Burtons Carpets Limited | Construction | 2010 |
| Bush and SON Ltd | Wholesale & retail | 2023 |
| Business & Manufacturing Excellence Ltd | Information & communication | 2024 |