| Birchwood Housing Limited | Real estate | 2023 |
| Birchwood Independence Ltd | Health & social care | 2018 |
| Bird-Friendly Farm Management Ltd. | Manufacturing | 2019 |
| Biscrok Limited | Information & communication | 2017 |
| Bishco Limited | Professional & scientific | 1999 |
| Bishop Fox's School | Education | 2011 |
| Bishop's Brook (Wells) Management Company Limited | Households | 2014 |
| Bishopbond Limited | Water & waste | 1982 |
| Bishops Lydeard Association Football Club Community Interest Company | Arts & recreation | 2008 |
| Bishops Lydeard Caravan and Camping Site Ltd | Hospitality | 2018 |
| Bishops Mead (Taunton) Limited | Households | 2007 |
| Bismillah Traders 787 Ltd | Hospitality | 2025 |
| BIT Healthcare Ltd | Wholesale & retail | 2017 |
| Bitesco Ltd | Hospitality | 2025 |
| Bitstrategy Ltd | Financial services | 2025 |
| Bittescombe Lodge Ltd | Hospitality | 2022 |
| Bittescombe Manor Estate Ltd | Agriculture & fishing | 2017 |
| Bitz Online Limited | Wholesale & retail | 2004 |
| Biztechsolutions Ltd | Information & communication | 2026 |
| Bizzar Limited | Wholesale & retail | 2018 |
| BJS Rentals Limited | Real estate | 2012 |
| BJS Stores Limited | Wholesale & retail | 2014 |
| BJW Logistics Ltd | Transport & logistics | 2016 |
| BK South West Engineering Limited | Professional & scientific | 2025 |
| BL Inspections Limited | Professional & scientific | 2015 |
| Black & White Project Management Limited | Construction | 2016 |
| Black Art Customs SW Limited | Wholesale & retail | 2020 |
| Black Eskimo Limited | Information & communication | 1998 |
| Black Hall Associates Limited | Financial services | 1994 |
| Black Heart Developments Ltd | Real estate | 2025 |
| Black Jumper Ltd | Administrative & support | 2016 |
| Black LAB Consulting Ltd | Professional & scientific | 2022 |
| Black LAB Investments Limited | Financial services | 2021 |
| Black LAB Property Group Ltd | Real estate | 2024 |
| Black Leopard Estates Limited | Real estate | 2010 |
| Black Lion Bikes Ltd | Wholesale & retail | 2012 |
| Black* Artists on the Move CIC | Health & social care | 2024 |
| Blackaton Power Limited | Energy | 2013 |
| Blackberry & Bay Catering Limited | Hospitality | 2024 |
| Blackbird Creative Ltd | Professional & scientific | 2022 |
| Blackbrook Management Services Limited | Real estate | 1992 |
| Blackbrooke Limited | Construction | 2026 |
| Blackdown Construction Limited | Construction | 2022 |
| Blackdown Dental Equipment Services Limited | Administrative & support | 2004 |
| Blackdown Electrical Limited | Construction | 2010 |
| Blackdown Hearing Ltd | Health & social care | 2020 |
| Blackdown Heating Ltd | Construction | 2023 |
| Blackdown Hills Business Association | Extraterritorial | 2003 |
| Blackdown Hills Creative Therapy Ltd | Education | 2022 |
| Blackdown IT Limited | Information & communication | 2019 |
| Blackdown Land Limited | Real estate | 2020 |
| Blackdown Meadow (2002) Management NO 1 Limited | Administrative & support | 2002 |
| Blackdown Meadow (2002) Management NO 2 Limited | Administrative & support | 2002 |
| Blackdown Meadow Management Company Limited | Households | 2020 |
| Blackdown Music Limited | Arts & recreation | 2017 |
| Blackdown Properties Limited | Extraterritorial | 1991 |
| Blackdown Scaffolding Ltd | Construction | 2025 |
| Blackdown Storage Limited | Other services | 2009 |
| Blackford Builders Limited | Construction | 2007 |
| Blackmoor Grange Gillingham Management Company (Number 1) Limited | Households | 2005 |
| Blackmore Electrical Limited | Construction | 2013 |
| Blackmore Vale Butchery Ltd | Professional & scientific | 2009 |
| Blacks Estate Holdings Ltd | Financial services | 2026 |
| Blackseam Construction Ltd | Construction | 2019 |
| Blackstock Farms Limited | Agriculture & fishing | 1944 |
| Bladeton Limited | Real estate | 2024 |
| Blake Dairy Farms Limited | Agriculture & fishing | 2014 |
| Blake Electrical Limited | Construction | 2014 |
| Blayney Grier Ltd | Information & communication | 2020 |
| BLB Solicitors Limited | Professional & scientific | 2017 |
| Blenheim Cottage (Management) Limited | Real estate | 1987 |
| Blenheim View Management Co. Limited | Hospitality | 1991 |
| Blessed Hands Bowls and Bites Ltd | Hospitality | 2025 |
| Blimey.Dev Limited | Information & communication | 2025 |
| Block Driveways Limited | Construction | 2018 |
| Blockworks Ltd | Professional & scientific | 2023 |
| Bloembollenadvies LLP | | 2015 |
| Blossom and Root Limited | Wholesale & retail | 2016 |
| Blue Acoustics One Limited | Professional & scientific | 2018 |
| Blue ARK Investments Limited | Real estate | 2018 |
| Blue Baboon Housing Ltd | Real estate | 2024 |
| Blue Bay Property Services (SW) Ltd | Construction | 2014 |
| Blue Guides Limited | Information & communication | 2004 |
| Blue Heron Holdings Ltd | Financial services | 2018 |
| Blue Mist Investments Limited | Extraterritorial | 2020 |
| Blue Moon Care Ltd | Health & social care | 2012 |
| Blue Moon London Cafe & Restaurant Ltd | Hospitality | 2023 |
| Blue PCN Limited | Health & social care | 2022 |
| Blue Sky Mentoring Ltd | Education | 2023 |
| Blue Swell Solutions Ltd | Professional & scientific | 2025 |
| Blue Tomato POP Limited | Administrative & support | 2011 |
| Bluechem GB Limited | Wholesale & retail | 2012 |
| Bluelab Corporation (UK) Limited | Wholesale & retail | 2011 |
| Blueprints Architectural Services Ltd | Professional & scientific | 2013 |
| Bluestar Homecare Ltd | Extraterritorial | 2017 |
| Bluestar UK Services Limited | Professional & scientific | 2005 |
| Bluestone Court RTM Company Limited | Households | 2021 |
| Bluewave Care Ltd | Health & social care | 2024 |
| Blush Hair & Beauty South West Limited | Other services | 2019 |
| Blythe Court Management (Taunton) Limited | Households | 1976 |