| Bowden Investment Holdings Limited | Financial services | 2025 |
| Bowdens Estate Agents Ltd | Real estate | 2025 |
| Bowel Trading Co., Ltd | Wholesale & retail | 2023 |
| Bowler Power Services Limited | Construction | 2008 |
| Bowller Environmental Electrical Systems Ltd | Construction | 2022 |
| Bowman Home Lettings Ltd | Real estate | 2017 |
| Bowood & Co Limited | Real estate | 2023 |
| Bowson Leeway Homes Limited | Construction | 2011 |
| Bowtif Ltd | Professional & scientific | 2021 |
| Boxed Events Limited | Hospitality | 2015 |
| Boxworth Inns Limited | Hospitality | 2012 |
| Boxworth Services Limited | Financial services | 2002 |
| Boyd & Associates Limited | Professional & scientific | 2015 |
| Boyraz Financial Management Ltd | Hospitality | 2018 |
| Bozkurt Family Limited | Hospitality | 2024 |
| BPK International Developments and Holdings Co Limited | Financial services | 2015 |
| Bplete Limited | Professional & scientific | 2021 |
| BPM Works Limited | Professional & scientific | 2003 |
| BPS Digital Platforms Limited | Information & communication | 2026 |
| BPS International UK Ltd | Wholesale & retail | 2023 |
| Bqcnc Ltd | Manufacturing | 2024 |
| BR Lifting Ltd | Wholesale & retail | 2023 |
| BR Medical Ltd | Health & social care | 2025 |
| Brace & Bloom Ltd | Manufacturing | 2025 |
| Brackens Court Management Company Limited | Households | 2007 |
| Bradbury Place Limited | Real estate | 2006 |
| Bradbury Property Solutions Limited | Real estate | 2019 |
| Bradley Lettings Limited | Real estate | 2019 |
| Bradnam Joinery Limited | Manufacturing | 1997 |
| Braescu Aviation Ltd | Manufacturing | 2025 |
| Braeside Residents' Association Limited | Households | 2001 |
| Brahler Holdings Limited | Financial services | 2012 |
| Brahm Ltd | Wholesale & retail | 2025 |
| Brain Logix Limited | Extraterritorial | 2013 |
| Brainminded Group Ltd | Financial services | 2026 |
| Brainminded Media Ltd | Information & communication | 2026 |
| Brainpatch Ltd | Manufacturing | 2018 |
| Brainwise Educational Services Ltd | Education | 2016 |
| Brainworx Limited | Information & communication | 2023 |
| Bralex Holdings Limited | Real estate | 2026 |
| Bram Troost (UK) Limited | Professional & scientific | 2023 |
| Bramble & Bloom Floristry Limited | Wholesale & retail | 2022 |
| Brambles Care Farm Limited | Health & social care | 2018 |
| Brambridge House Estates Limited | Professional & scientific | 1966 |
| Bran Properties Limited | Hospitality | 2021 |
| Branch Nayoni Trading Co., Limited | Extraterritorial | 2021 |
| Branches Park Hatcheries Ltd | Agriculture & fishing | 2009 |
| Brand Marketing & Consultancy Ltd | Administrative & support | 2015 |
| Brand Property Developments Limited | Construction | 2025 |
| Brandon House Management Company Limited | Real estate | 2016 |
| Brangaene Limited | Administrative & support | 2015 |
| Branigan Consulting Ltd | Education | 2024 |
| Brantas Homes LLP | | 2022 |
| Brasmart Ltd | Wholesale & retail | 2025 |
| Braun Composites Ltd | Manufacturing | 2023 |
| Braundcreative Ltd | Professional & scientific | 2013 |
| Bravelycultured Ltd | Professional & scientific | 2022 |
| Bravo Cafe Patisserie Ltd | Hospitality | 2018 |
| Bravo Enterprises Limited | Manufacturing | 2018 |
| Bravo Joy Ltd | Information & communication | 2026 |
| Braybrooke Road Desborough Ltd | Construction | 2017 |
| Brazilichilli Ltd | Hospitality | 2026 |
| Brdgthegap Limited | Information & communication | 2025 |
| Bread & Meat Limited | Hospitality | 2014 |
| Bread Theatre and Film Company | Administrative & support | 2019 |
| Break Fourth Ltd | Information & communication | 2025 |
| Breakfast Voyage Ltd | Hospitality | 2025 |
| Breakspear Homes Limited | Real estate | 2021 |
| Breakwater Associates Limited | Professional & scientific | 2019 |
| Breasthealth UK Limited | Health & social care | 2009 |
| Breathe Technology Limited | Information & communication | 2003 |
| Breeio Ltd | Information & communication | 2024 |
| Breeze Taxis Ltd | Transport & logistics | 2023 |
| Breitling Connections Limited | Real estate | 2019 |
| Bremen Trading Co., Ltd | Wholesale & retail | 2023 |
| Bremner Partnership LLP | | 2011 |
| Brendan Norris Brickwork and Construction Limited | Construction | 2015 |
| Brennan Composites Ltd | Manufacturing | 2017 |
| Brenthall Building Services Ltd | Construction | 2006 |
| Bretany Ltd | Extraterritorial | 2005 |
| Brewboard Limited | Manufacturing | 2016 |
| Brewista Limited | Hospitality | 2018 |
| BRG Contractors Ltd | Construction | 2020 |
| Brian and BOB Ltd | Wholesale & retail | 2023 |
| Brian Cumming Sky Ltd | Education | 2022 |
| Brian Cumming Tunnel Ltd | Education | 2023 |
| Brian Gale Associates Ltd | Professional & scientific | 2018 |
| Brian Langley & SON Limited | Construction | 2003 |
| Brian Meacher Quality & Compliance Management Limited | Professional & scientific | 2019 |
| Brian Wang Education Group London UK Ltd | Other services | 2021 |
| Brianphoenixmartin Ltd | Manufacturing | 2023 |
| Briar Security Systems Limited | Other services | 2001 |
| Brick Marketing Limited | Professional & scientific | 2018 |
| Brickhills Management Limited | Real estate | 2016 |
| Brickhouse Cafe Ltd | Hospitality | 2025 |
| Bricks ST Property Group Ltd | Administrative & support | 2012 |
| Bridge Advisory Ltd | Professional & scientific | 2026 |
| Bridge Cabs Limited | Transport & logistics | 2024 |
| Bridge Family Matters Limited | Professional & scientific | 2017 |
| Bridge Farmhouse Investments Limited | Professional & scientific | 2019 |