| Bezier Solutions Limited | Information & communication | 2009 |
| BGA Consulting Ltd | Wholesale & retail | 2020 |
| BH Marine (UK) LLP | | 2011 |
| BH Marine Academy LLP | | 2019 |
| BH Marine Consultancy Ltd | Professional & scientific | 2019 |
| BH Marine Deliveries Ltd | Transport & logistics | 2019 |
| BI & JA Dennis Limited | Other services | 2010 |
| Bibi's Home Limited | Wholesale & retail | 2017 |
| Big Drone Company Ltd | Professional & scientific | 2025 |
| Billings & Vincent Limited | Construction | 2018 |
| Bincombe Park Limited | Construction | 2021 |
| Biopharmaspec (UK) Limited | Extraterritorial | 2014 |
| Birch Social Limited | Health & social care | 2022 |
| Bishop C Limited | Wholesale & retail | 2017 |
| Bitfusion Ltd | Information & communication | 2023 |
| Bj's of Ringwood Limited | Hospitality | 2010 |
| BJM South Ltd | Construction | 1998 |
| Black Goat Barber Co. Ltd | Other services | 2023 |
| Blacknoll Building Contractors Limited | Construction | 2013 |
| Blackwell Supplies Ltd | Wholesale & retail | 2012 |
| Blenkinsop Water Treatment Consultancy Ltd | Water & waste | 2022 |
| Blighty Services Limited | Manufacturing | 2018 |
| Blitz Contracts Ltd | Administrative & support | 2023 |
| Blo-Op Limited | Manufacturing | 2013 |
| Blossoms Bees Ltd | Manufacturing | 2025 |
| Blue Sky Cafe Weymouth Limited | Hospitality | 2025 |
| Bluebird Coaches (Holdings) Limited | Administrative & support | 2019 |
| Bluebird Coaches (Weymouth) Limited | Administrative & support | 2000 |
| Blues Hope Ltd | Wholesale & retail | 2025 |
| Blundell Harling Limited | Manufacturing | 1948 |
| Blunmade Limited | Real estate | 1998 |
| BM Weymouth Limited | Wholesale & retail | 2015 |
| BMB Operations Ltd | Professional & scientific | 2019 |
| BMB Ventures Limited | Real estate | 2025 |
| Boardz Limited | Wholesale & retail | 2021 |
| Bodhi Leaf Massage and Therapy Ltd | Health & social care | 2024 |
| Body Soul & Spirit Ltd | Wholesale & retail | 2001 |
| Boh-Emia Bars Limited | Hospitality | 2025 |
| Boisse Window Services Limited | Construction | 2023 |
| Boisse Windows (Weymouth) Limited | Construction | 2013 |
| Boldhabit Limited | Real estate | 1994 |
| Bolton Brow Halifax Leasehold 57 Ltd | Real estate | 2026 |
| Bond Developments Limited | Real estate | 2011 |
| Bond Street Management Ltd | Households | 2025 |
| Bond Tech Repairs Ltd | Other services | 2026 |
| Boone & Co Limited | Wholesale & retail | 2018 |
| Bowcroft Oaks LLP | | 2020 |
| Bowker Marine Services LLP | | 2014 |
| Bowleaze Limited | Hospitality | 2009 |
| Bowleaze Management Limited | Households | 2009 |
| Brand Transformation and Growth Ltd | Professional & scientific | 2025 |
| Brankling Petroscience Limited | Mining & quarrying | 2012 |
| Brave Bold Drama Community Interest Company | Arts & recreation | 2017 |
| Brendon Hill Tree Services Limited | Administrative & support | 2002 |
| Brian Riggs Electrical Ltd | Construction | 2013 |
| Bridge House (Weymouth) Management Company Limited | Real estate | 2006 |
| Bridge the GAP Facilitators Ltd | Health & social care | 2020 |
| Bridwey PM Holdings Limited | Financial services | 2025 |
| Bridwey Precision Manufacturing Limited | Professional & scientific | 2002 |
| Brighter Horizons Training LLP | | 2022 |
| Brimsmore Beauty Ltd | Other services | 2025 |
| Brink Laser Tattoo Removal Ltd | Other services | 2022 |
| Broad Oaks Halifax Leasehold 57 Ltd | Real estate | 2026 |
| Broadcroft Management Co Ltd | Households | 2020 |
| Broadreach (Southern) Ltd | Construction | 2003 |
| Broadtech Network Systems Limited | Information & communication | 2011 |
| Broadway Estate Limited | Real estate | 1926 |
| Broatch Engines Ltd | Professional & scientific | 2015 |
| Brookes Taylor Limited | Hospitality | 2025 |
| Brookeshouse Developments Limited | Construction | 2022 |
| Broscots Ltd | Wholesale & retail | 2019 |
| Brown Dog Aviation Limited | Manufacturing | 2020 |
| Brown Group Consulting Ltd | Information & communication | 2025 |
| Brown Property Developments Limited | Construction | 2025 |
| Brown's Home & Garden Ltd | Construction | 2024 |
| Brubrock Ltd | Real estate | 2022 |
| Bryant Inspection Services Limited | Professional & scientific | 2009 |
| Bryher Boatyard Holdings Limited | Financial services | 2021 |
| BS73 Limited | Manufacturing | 2026 |
| BSC Estates Ltd | Real estate | 2020 |
| BSD Waste Limited | Water & waste | 2018 |
| Bsfc ELY Limited | Arts & recreation | 2012 |
| BTM Property Limited | Real estate | 2021 |
| Buckland Field Camping Ltd | Real estate | 2021 |
| Buckler Environmental Services Limited | Construction | 2003 |
| Budmouth Limited | Arts & recreation | 1991 |
| Bugs, Bones & Botany CIC | Education | 2025 |
| Buildcraft Construction Limited | Construction | 2004 |
| Builders D J Limited | Financial services | 2014 |
| Building Services (Weymouth) Limited | Real estate | 1984 |
| Building Services Holdings Limited | Real estate | 1987 |
| Buildrite Trade and DIY Supplies Ltd | Wholesale & retail | 1999 |
| Burst of Beauty Ltd | Other services | 2026 |
| Burton Chapel Records Ltd | Information & communication | 2024 |
| Buster BEN Fishing Ltd | Agriculture & fishing | 2018 |
| Bustinskin Events Ltd | Arts & recreation | 2012 |
| Butch's Land Co Limited | Real estate | 2021 |
| Butch's Park Holdings Limited | Financial services | 2021 |
| Butch's Park Limited | Professional & scientific | 2013 |
| Butterdoughs Ltd | Manufacturing | 2025 |