| Baclon Limited | Real estate | 1964 |
| BAD Management Services Ltd | Professional & scientific | 2023 |
| BAD Taste Pictures Ltd. | Information & communication | 2016 |
| Badger Digital Limited | Information & communication | 2023 |
| Badlinu Productions Ltd | Information & communication | 2022 |
| Badshirtz Limited | Wholesale & retail | 2026 |
| Baggette & Company Wealth Management Limited | Financial services | 2010 |
| Baileyco Ltd | Real estate | 2023 |
| Baillie Park Management Company Limited | Households | 2005 |
| Baillieus' Butchers Limited | Wholesale & retail | 2010 |
| Bake HQ Ltd | Arts & recreation | 2024 |
| Bake Vibe Ltd | Manufacturing | 2025 |
| Baker Davies Ltd | Financial services | 1997 |
| Balanced Days Ltd | Manufacturing | 2026 |
| Balanzi Ltd | Wholesale & retail | 2020 |
| Balcombe Breeze Limited | Households | 2018 |
| Baldwin Mews - Warburton Road Ltd | Households | 2017 |
| Baldy Limited | Real estate | 2013 |
| Balfe Contracting Ltd | Construction | 2016 |
| Balfern Grove Ltd | Real estate | 2018 |
| Ball Lednor Healthcare Limited | Health & social care | 2018 |
| Ball Roofing & Property Ltd | Construction | 2018 |
| Ballard Bay Holdings Ltd | Financial services | 2024 |
| Ballard Bay Property Holdings Limited | Real estate | 2024 |
| Balldoco Ltd | Manufacturing | 2023 |
| Ballers at HIS Feet Limited | Wholesale & retail | 2023 |
| Balloon Madness Ltd | Wholesale & retail | 2022 |
| Balloon Price Consulting Limited | Professional & scientific | 2018 |
| Balmoral House Management Ltd | Households | 2010 |
| Balson Penn-Hill Ltd | Professional & scientific | 2012 |
| Baltic Export Limited | Wholesale & retail | 2023 |
| BAM Automotive Ltd | Wholesale & retail | 2019 |
| Bambi Social Ltd | Professional & scientific | 2023 |
| Bambini Lingo Ltd | Health & social care | 2014 |
| Bamboo Landscapes Limited | Administrative & support | 2015 |
| Banana Developments Ltd | Real estate | 2015 |
| Bancroft Court Freehold Limited | Households | 2002 |
| Band SIX Ltd | Wholesale & retail | 2021 |
| Bani Ascendant Ltd | Wholesale & retail | 2018 |
| Bani Zaid Ltd | Wholesale & retail | 2025 |
| Baniad Ltd | Wholesale & retail | 2022 |
| Banian Capital Management Ltd | Financial services | 2025 |
| Banks and Bay Developments Limited | Construction | 2020 |
| Banks and Bay Interiors Limited | Professional & scientific | 2022 |
| Banks Bespoke Joinery Ltd | Construction | 2021 |
| Banner Homes (Bournemouth) Ltd | Real estate | 2019 |
| Banocube Limited | Information & communication | 2014 |
| Banyard Construction Holdings Ltd | Financial services | 2024 |
| Banyard Construction Limited | Construction | 1998 |
| Barbers Gate Limited | Other services | 2003 |
| Barbot Technology Ltd | Information & communication | 2026 |
| Bards Collective Limited | Professional & scientific | 2014 |
| Barefoot Life Trading Ltd | Wholesale & retail | 2025 |
| Barilla Management Company Limited | Real estate | 2004 |
| Bark Avenue Accessories Ltd | Wholesale & retail | 2023 |
| Barking Cat Brewing Company Ltd. | Manufacturing | 2025 |
| Barnaby Advertising Limited | Administrative & support | 2007 |
| Barnet & Belle Limited | Other services | 2019 |
| Barnet Quality Care Ltd | Health & social care | 2024 |
| Baron + Baron Architects Limited | Professional & scientific | 2019 |
| Barrack Express Ltd | Hospitality | 2023 |
| Barrett Associates Ltd | Professional & scientific | 2011 |
| Barrett Mortgages Ltd | Financial services | 2017 |
| Barrie William Halbert Ltd | Manufacturing | 2016 |
| Barrington Court Maintenance (Ferndown) Limited | Households | 1973 |
| Barrington Energy Solutions Ltd | Construction | 2022 |
| Barrington Gate (Branksome) Management Company Limited | Households | 2004 |
| Barrington Homes (Poole) Limited | Construction | 2008 |
| Barrington Homes (Property) Limited | Construction | 2003 |
| Bart Transport & Logistics Ltd | Transport & logistics | 2025 |
| Bartbase Ltd | Information & communication | 2025 |
| Bartholomew Professional Services Limited | Administrative & support | 2011 |
| Bartlett Investments Limited | Financial services | 2025 |
| Bartley Green Properties Ltd | Real estate | 2026 |
| Bartosh Logistics Ltd | Administrative & support | 2017 |
| Bartosz Kapteina Ltd | Transport & logistics | 2026 |
| Bascott Renewables Limited | Energy | 2016 |
| Base Holdings (South West) Ltd | Wholesale & retail | 2023 |
| Base Movement Limited | Arts & recreation | 2023 |
| Baseone Innovations Limited | Information & communication | 2026 |
| Basis Lighting Limited | Manufacturing | 1991 |
| Basit Abdul Ltd | Wholesale & retail | 2025 |
| Basix Bellevilles Ltd | Wholesale & retail | 2016 |
| Basma AL Ghassani Limited | Wholesale & retail | 2025 |
| Bastien Ventures Ltd | Information & communication | 2023 |
| Batch 92 Ltd | Financial services | 2025 |
| Batch Group Ltd | Information & communication | 2023 |
| Batchelor Electrical Limited | Construction | 1992 |
| Batchelor Fire & Security Limited | Construction | 2013 |
| Batchelor Renewable Energy Limited | Construction | 2024 |
| Bath Bubble and Beyond Limited | Extraterritorial | 2009 |
| Bathroom Store (Lyndhurst) Limited | Extraterritorial | 2007 |
| Bathtub Bingo Ltd | Hospitality | 2024 |
| Batkeys Ltd | Wholesale & retail | 2019 |
| Batten Dorset Ltd | Other services | 2014 |
| Battle Bird Productions Ltd | Wholesale & retail | 2020 |
| Battle Candy Studios Ltd | Information & communication | 2020 |
| Bauen Solutions Ltd | Information & communication | 2026 |
| Baxendale Jones Limited | Professional & scientific | 2012 |
| Baxter Court RTM Company Limited | Hospitality | 2012 |