| Brighter IR Limited | Information & communication | 2016 |
| Brightfone Limited | Wholesale & retail | 2011 |
| Brightforge Technologies Limited | Information & communication | 2026 |
| Brightlands Energy Ltd | Professional & scientific | 2016 |
| Brightlife Property Ltd | Real estate | 2024 |
| Brightsky Energy Ltd | Construction | 2024 |
| Brilliance Beauty Ltd | Other services | 2026 |
| Brilliant Distribution Limited | Wholesale & retail | 2010 |
| Briony Wood Limited | Real estate | 2018 |
| Bristol Impressionist Limited | Financial services | 2022 |
| Briut Global Limited | Professional & scientific | 2018 |
| BRM IT Solutions Limited | Information & communication | 2026 |
| Broad Power Holdings Limited | Financial services | 2022 |
| Broad Power Solutions Limited | Wholesale & retail | 2003 |
| Broadbase Business Services Limited | Professional & scientific | 2018 |
| Broadmayne Developments (Dorset) Limited | Real estate | 1997 |
| Broadsail Ltd | Professional & scientific | 2022 |
| Broadstone News Ltd | Wholesale & retail | 2011 |
| Broadview Plumbing and Heating Ltd | Construction | 2018 |
| Broadwater Estates Ltd. | Real estate | 2015 |
| Brock House Enterprises Limited | Information & communication | 2020 |
| Brockenhurst Consulting Ltd | Information & communication | 2012 |
| Brodie Braque Limited | Information & communication | 2024 |
| Brokernet Ltd | Financial services | 2021 |
| Brontique Homes Limited | Construction | 2025 |
| Brookleigh Holdings Ltd | Real estate | 2025 |
| Brooklyn Homes Brickwork Limited | Construction | 2022 |
| Brooklyn Homes Developments Ltd | Construction | 2001 |
| Brooklyn Homes Groundworks Limited | Construction | 2012 |
| Brooklyn Management Dorset Limited | Professional & scientific | 2015 |
| Brooks Developments Limited | Real estate | 2016 |
| Brother Brickwork Ltd | Construction | 2009 |
| Brother Brickwork South Ltd | Construction | 2020 |
| Brothers Farm Ltd | Agriculture & fishing | 2019 |
| Brown AI Ltd | Information & communication | 2022 |
| Brown INK Collective Limited | Transport & logistics | 2015 |
| Browning Consultancy Limited | Professional & scientific | 2016 |
| Browning Real Estate Ltd | Real estate | 2013 |
| BRS Coaching Academy Limited | Education | 2016 |
| BRU Hub Ltd | Hospitality | 2025 |
| Brymanor Operations Limited | Real estate | 2026 |
| BS Aero (ENG) Ltd | Manufacturing | 2026 |
| BSL Hire Limited | Construction | 2000 |
| BSW (Wimborne) Limited | Professional & scientific | 2015 |
| BT ERP Consulting Limited | Information & communication | 2022 |
| BT Services Ltd | Professional & scientific | 2025 |
| BTS Properties Ltd | Households | 2019 |
| Buckfield Signs Ltd | Professional & scientific | 2000 |
| Buddens Consultants Ltd | Professional & scientific | 2010 |
| Buddens Meadow Management Limited | Households | 2002 |
| Buencampo Ltd | Information & communication | 2022 |
| Bugle Collective Ltd | Professional & scientific | 2026 |
| Bugtrap Ltd | Information & communication | 2014 |
| Build and Ship Academy Ltd | Information & communication | 2026 |
| Build-Right (South) Ltd | Construction | 2020 |
| Building Products Index Limited | Administrative & support | 2003 |
| Bullfinch Capital Limited | Real estate | 2022 |
| Bullion Agents Limited | Information & communication | 2026 |
| Buoys Construction Services Limited | Construction | 2020 |
| Burcart Development and Management Ltd | Construction | 2018 |
| Burke Consulting Limited | Professional & scientific | 2020 |
| Burley's Commercial Holdings Limited | Real estate | 2015 |
| Burley's Home Care Services Ltd | Health & social care | 2009 |
| Burley's Property Holdings Limited | Real estate | 2026 |
| Burlington Mansions Management Company Limited | Households | 2001 |
| Burnham House Media Ltd | Information & communication | 2025 |
| Burrows Coaches Limited | Transport & logistics | 2020 |
| Burrows Marine Limited | Administrative & support | 2022 |
| Burton Optical Ltd | Health & social care | 2018 |
| Burwell Consult Limited | Professional & scientific | 2025 |
| Buscraft Ltd | Wholesale & retail | 2022 |
| Business Assist Group Limited | Professional & scientific | 2002 |
| Business Consulting and IT Solutions Limited | Information & communication | 2005 |
| Business Enterprises Limited | Information & communication | 2009 |
| Business Hub Services Limited | Administrative & support | 2015 |
| Business Intelligence Contracting Ltd | Professional & scientific | 2013 |
| Bustajobs External Cleaning Ltd | Administrative & support | 2022 |
| Bustajobs Ltd | Water & waste | 2020 |
| Busy Bees Recruitment Ltd | Administrative & support | 2024 |
| Buttercup Lane 7-15 Management Company Limited | Households | 2025 |
| Buttertubs Limited | Information & communication | 2008 |
| BV Infrastructure Limited | Professional & scientific | 2026 |
| BWC Music Ltd | Information & communication | 2017 |
| Byers Consulting Ltd | Professional & scientific | 2024 |
| Byjp Limited | Information & communication | 2025 |
| Byrne IT Consulting Limited | Information & communication | 2019 |
| Byrons Bespoke Flooring Ltd | Construction | 2021 |
| Byteforge Solutions Ltd | Information & communication | 2024 |
| Bytewyrm Limited | Information & communication | 2025 |
| C & C Pomfret Limited | Agriculture & fishing | 2014 |
| C and J Fenceworks Ltd | Construction | 2025 |
| C and J Wimborne Limited | Professional & scientific | 2006 |
| C D B Engineering Ltd | Manufacturing | 2006 |
| C G Purchase and SON Limited | Agriculture & fishing | 1958 |
| C M P Services Ltd | Wholesale & retail | 2021 |
| C Sait Limited | Wholesale & retail | 2020 |
| C Sait Products Limited | Wholesale & retail | 2025 |
| C T Hughes Consultancy Limited | Information & communication | 2011 |
| C&C Technology and Consulting Limited | Information & communication | 2020 |
| C.A. Spearing & SON Limited | Wholesale & retail | 2003 |