| Brasco Ltd | Real estate | 2025 |
| Brazier Estates Limited | Extraterritorial | 2023 |
| Brazzos Limited | Professional & scientific | 1997 |
| Brdbx Ltd | Arts & recreation | 2024 |
| Bread and BUS Stop Ltd | Arts & recreation | 2024 |
| Breakwater Construction Ltd | Construction | 2026 |
| Breamore Technical Services Ltd | Mining & quarrying | 2021 |
| Bredon Construction & Haulage (Wareham) Limited | Construction | 1988 |
| Breeze Beauty Salon Ltd | Other services | 2019 |
| Brelona Ltd | Health & social care | 2018 |
| Brett Parker Car Sales Ltd | Wholesale & retail | 2022 |
| Brewery Square Management Limited | Households | 2008 |
| Brick Lane Surveyors Ltd | Professional & scientific | 2023 |
| Bridal Reloved Franchising Ltd | Wholesale & retail | 2014 |
| Bride Valley Alpaca Ltd | Agriculture & fishing | 2016 |
| Bride Valley Newsagents Limited | Wholesale & retail | 2003 |
| Bride Valley Vineyard Limited | Agriculture & fishing | 2006 |
| Bridge Cottages (MN) Limited | Households | 2022 |
| Bridge Court Management (Dorchester) Limited | Households | 1990 |
| Bridge Cove Limited | Construction | 2006 |
| Bridgeport 360 Limited | Construction | 2018 |
| Bridport Road Management Company Limited | Households | 2010 |
| Bright Blue Enterprises Ltd | Manufacturing | 2022 |
| Bright Button Productions Limited | Administrative & support | 2010 |
| Bright Light Research and Analysis Limited | Professional & scientific | 2011 |
| Brighter Starts Limited | Health & social care | 2025 |
| Brimar Leisure Limited | Hospitality | 2020 |
| Brimsmore Fruit Farm Limited | Wholesale & retail | 1976 |
| Britain for ALL Limited | Information & communication | 2019 |
| Britavia Limited | Real estate | 1996 |
| Britlift Ltd | Manufacturing | 2017 |
| Broadbury Trading Co. Limited | Wholesale & retail | 2014 |
| Broadwey Motors (Weymouth) Limited | Transport & logistics | 1980 |
| Broadwindsor Healthcare Limited | Health & social care | 2020 |
| Brockhampton Ltd | Manufacturing | 2018 |
| Bronzeology Limited | Other services | 2022 |
| Bronzology Bournemouth Limited | Other services | 2023 |
| Brookland Travel Ltd. | Administrative & support | 1999 |
| Brooksmiths Limited | Other services | 2006 |
| Browser London Limited | Administrative & support | 2008 |
| BRT Technical Services Limited | Professional & scientific | 2005 |
| Bruf Contract Holdings Limited | Real estate | 1964 |
| Brunton's Propellers Limited | Manufacturing | 1919 |
| Bsld Ltd | Real estate | 2000 |
| Btpd the Makers Studio Ltd | Manufacturing | 2025 |
| Buchanan Estates Ltd | Construction | 2018 |
| Buckland Art Limited | Arts & recreation | 2001 |
| Buckland Carpentry Limited | Construction | 2007 |
| Buckland Films Limited | Information & communication | 1984 |
| Buckland Newton CPT Limited | Hospitality | 2007 |
| Buckland Newton Hire Limited | Administrative & support | 1990 |
| Bucklebury Farm Limited | Agriculture & fishing | 2020 |
| Bucklebury Limited | Professional & scientific | 2019 |
| Buckwheat Bakery Ltd | Manufacturing | 2024 |
| Buddha on a Bicycle Ltd | Other services | 2008 |
| Bugfest Limited | Education | 2018 |
| Buildbeam Building Services Limited | Construction | 2026 |
| Burden's Garden Services Ltd | Agriculture & fishing | 2018 |
| Bureau DE Posh Ltd | Wholesale & retail | 2024 |
| Burford Gardens Management Limited | Real estate | 2016 |
| Burn Technology Limited | Information & communication | 2001 |
| Burton Landscapes Limited | Administrative & support | 2013 |
| Business Development Management Ltd | Administrative & support | 2021 |
| Busy Clapham Ltd | Other services | 2023 |
| BWK Construction Ltd | Construction | 2021 |
| BWW Architects Limited | Professional & scientific | 2022 |
| Byatt-Day Property Ltd | Real estate | 2023 |
| Byldya Ltd | Construction | 2018 |
| C Hughes Building Limited | Construction | 2022 |
| C R Carpets Limited | Wholesale & retail | 2007 |
| C Taylor Limited | Administrative & support | 2013 |
| C&P Construction Ltd | Construction | 2017 |
| C-Max Limited | Manufacturing | 1992 |
| C. & T. Publications Limited | Extraterritorial | 1961 |
| C.G. FRY and SON (NO.2) Limited | Real estate | 2017 |
| C.G. FRY and SON Limited | Construction | 1983 |
| C.J. Hooper and Sons Limited | Agriculture & fishing | 1961 |
| C19C Health Limited | Health & social care | 2020 |
| C19C Limited | Professional & scientific | 2020 |
| Cabildo Limited | Administrative & support | 2018 |
| Cafe by the Lakes Ltd | Wholesale & retail | 2014 |
| Cahill Motor Services (Dorchester) Limited | Wholesale & retail | 2016 |
| CAL Design & Construction Services Ltd | Construction | 2019 |
| Californian Rush Limited | Administrative & support | 2009 |
| Call the 5'S Ltd | Transport & logistics | 2024 |
| Callaways Property Maintenance Limited | Construction | 2018 |
| Calvco Limited | Professional & scientific | 2009 |
| Camber Cycle Works Ltd | Manufacturing | 2021 |
| Cambio Business Solutions Limited | Professional & scientific | 2008 |
| Came Down Golf Club Limited | Arts & recreation | 2019 |
| Came Down Trading Limited | Arts & recreation | 2020 |
| Campbellwicks Interiors Ltd | Wholesale & retail | 2017 |
| CAN YOU DIG IT Ltd | Administrative & support | 2006 |
| Cancer Diagnostic Quality Assurance Services Community Interest Company | Professional & scientific | 2014 |
| Canford Aerospace Limited | Professional & scientific | 2017 |
| Canopy Access Limited | Extraterritorial | 2008 |
| Cape Farewell (0CEAN) | Arts & recreation | 2002 |
| Capelli of Poundbury Limited | Other services | 2006 |
| Capers Day Nursery Ltd | Health & social care | 2015 |
| Capital Barriers and Temporary Fencing Limited | Administrative & support | 2018 |