| Bots Automation Limited | Manufacturing | 2021 |
| Botulinum Toxin Club Ltd | Other services | 2024 |
| Bounty Media Ltd | Professional & scientific | 2022 |
| Bournehall Properties Limited | Real estate | 1999 |
| Bovingdon Court Residents Association Limited | Households | 1979 |
| Bowley Estates Limited | Real estate | 2022 |
| Bowling Green Dental Surgery Limited | Health & social care | 2013 |
| Bowmans Mill Limited | Real estate | 2016 |
| Boxer Marine Services Limited | Professional & scientific | 2018 |
| Boxroute UK Limited | Wholesale & retail | 2025 |
| Boyle's French Polishers Limited | Administrative & support | 1994 |
| BR Engineering Solutions Limited | Manufacturing | 2009 |
| BR Events Ltd | Administrative & support | 2023 |
| Braand Ltd | Arts & recreation | 2018 |
| Bracey's Accountants (Medical) Limited | Professional & scientific | 2014 |
| Bracey's Accountants (Stevenage) Limited | Professional & scientific | 2016 |
| Bracimedica Limited | Health & social care | 2025 |
| Bradells Co. 1 Ltd | Arts & recreation | 2024 |
| Bradells Co. 3 Ltd | Arts & recreation | 2025 |
| Bradells Co. 4 Ltd | Arts & recreation | 2026 |
| Bradells Holdings Ltd | Financial services | 2025 |
| Bragbury Barns Management Company Limited | Real estate | 2015 |
| Bragbury House Management Co. Ltd. | Households | 2006 |
| Bragbury Manor Residents Limited | Households | 2005 |
| Braham Medics Ltd | Health & social care | 2015 |
| Braidwood General Management Company Limited | Households | 2002 |
| Brambles Childminding Ltd | Health & social care | 2019 |
| Brammingham Masowe Johane Chishanu Luton Ltd | Other services | 2021 |
| Brandhit Limited | Extraterritorial | 2004 |
| Brandt Kitchens Limited | Wholesale & retail | 2005 |
| Brangetsfit Ltd | Arts & recreation | 2025 |
| Brave Freedom Ltd | Real estate | 2019 |
| Breadwinners Limited | Professional & scientific | 2004 |
| Breaking Artz Group Ltd | Arts & recreation | 2024 |
| Breeze Cleaning Solutions Limited | Administrative & support | 2026 |
| Brewin Properties Limited | Real estate | 2018 |
| Brewing Works Limited | Manufacturing | 2021 |
| BRH Commercials Limited | Wholesale & retail | 2023 |
| Briar Court Irthlingborough Management Limited | Other services | 2004 |
| Brick & Brush Builders Ltd | Construction | 2025 |
| Brickfield Haulage Ltd | Transport & logistics | 2024 |
| Bricklay Limited | Real estate | 1988 |
| Bricks Hotel Management Ltd | Hospitality | 2023 |
| Bricks to Units Ltd | Real estate | 2023 |
| Bridge Events Ltd | Administrative & support | 2014 |
| Bridge Facial Aesthetics Limited | Health & social care | 2019 |
| Bridge Hill Epping Limited | Other services | 2022 |
| Bridgecam Solutions Ltd | Information & communication | 2019 |
| Bridgecare Solutions Ltd | Health & social care | 2009 |
| Bridgman Property Ltd | Real estate | 2019 |
| Bridgwater Consultancy Ltd | Professional & scientific | 2026 |
| Brierev Holdings | Financial services | 2016 |
| Brighter Electrical Services Limited | Construction | 2016 |
| Brighter Futures Educational Trust | Education | 2016 |
| Brightpath Electrical Services Ltd | Construction | 2025 |
| Brigit's Afternoon Tea Limited | Wholesale & retail | 2011 |
| Brigit's Bakery (Bath) Limited | Wholesale & retail | 2011 |
| Brigit's Bakery (Edinburgh) Limited | Wholesale & retail | 2017 |
| Brigit's Bakery (Holdings) Limited | Financial services | 2012 |
| Brigit's Bakery (Oxford) Limited | Wholesale & retail | 2017 |
| Brigit's Cook Limited | Wholesale & retail | 2012 |
| Brigit's Franchise Limited | Administrative & support | 2019 |
| Brigit's Media Limited | Wholesale & retail | 2017 |
| Brigit's Motorz Limited | Wholesale & retail | 2017 |
| Brilliantin Recruitment Ltd | Professional & scientific | 2020 |
| Brimchalk Healthcare Ltd | Health & social care | 2019 |
| Brit Asia Travel Limited | Administrative & support | 2026 |
| Britannia Sovereign Property Ltd | Real estate | 2025 |
| Brithealth Care Clinics Limited | Health & social care | 2013 |
| Brithealth Limited | Health & social care | 1988 |
| British Aerosol Manufacturers' Association | Other services | 1983 |
| British Parts Limited | Wholesale & retail | 2004 |
| Brittain Rigging Limited | Construction | 2021 |
| Broadband Technology 2000 Limited | Wholesale & retail | 1995 |
| Broadoak Advisors Limited | Financial services | 2025 |
| Broadshield Limited | Information & communication | 2011 |
| Broadwater Books Ltd | Information & communication | 2026 |
| Broadwater Farmhouse Management Company Limited | Households | 1995 |
| Broadwater Teeth Ltd | Health & social care | 2019 |
| Broadway House (Wokingham) Limited | Real estate | 2002 |
| Brofield Group Limited | Manufacturing | 2017 |
| Broit Limited | Wholesale & retail | 2024 |
| Broken Robot Productions Ltd | Other services | 2017 |
| Broken Staff Ltd | Information & communication | 2023 |
| Bromfield Car Repairs Ltd | Wholesale & retail | 2025 |
| Brooks Direct Ltd | Wholesale & retail | 2022 |
| Brookside (Bedford Road) Limited | Construction | 2022 |
| Brooksy Holdings Ltd | Financial services | 2024 |
| Broomey Croft Farm Ltd | Other services | 2024 |
| Broomford Holdings Limited | Professional & scientific | 2006 |
| Broomford Thamesway Limited | Professional & scientific | 2006 |
| Brora Limited | Wholesale & retail | 2001 |
| Brora Trustees Limited | Administrative & support | 2023 |
| Brow LAB Limited | Other services | 2023 |
| Brown & LEE Commercial Surveyors LLP | | 2015 |
| Browne Hospitality Limited | Professional & scientific | 2025 |
| Bryan Derma Ltd | Health & social care | 2023 |
| Bryant + Moore Architects Limited | Professional & scientific | 2008 |
| Brycelands Removals and Storage Limited | Transport & logistics | 2021 |
| Brzc Ltd | Construction | 2020 |