| Booking Experts Ltd | Hospitality | 2019 |
| Boomsse Limited | Wholesale & retail | 2025 |
| Borarda Ltd | Extraterritorial | 2024 |
| Borealys Limited | Administrative & support | 2024 |
| Boredofchores.Com Ltd | Other services | 2007 |
| Borkwood Court (Orpington) RTM Company Limited | Real estate | 2026 |
| Borough Finance Ltd | Professional & scientific | 2025 |
| Borvis Limited | Construction | 2020 |
| Bosco Records Limited | Information & communication | 2023 |
| Bosston Driveways and Patios Ltd | Construction | 2022 |
| Bosston Ltd | Construction | 2011 |
| Boswell Court Limited | Households | 2002 |
| Botworks Limited | Information & communication | 2022 |
| Boulis Enterprises Ltd | Administrative & support | 2017 |
| Boulis Properties Ltd | Real estate | 2021 |
| Bounce Empire Limited | Administrative & support | 2017 |
| Bourne Vale Allotments Limited | Arts & recreation | 2020 |
| Bourne View Limited | Households | 2024 |
| Boutique Balloons Kent Limited | Wholesale & retail | 2017 |
| Bovini Holdings Limited | Financial services | 2024 |
| BOW Bridge (Stratford) Limited | Households | 2006 |
| Bowdens Property Management Ltd | Construction | 2024 |
| Bowerdean RTM Company Limited | Households | 2023 |
| Bowmel Limited | Wholesale & retail | 1989 |
| Box Colony Limited | Real estate | 2025 |
| Boxed TV Ltd | Information & communication | 2012 |
| Boyzone Publishing Limited | Information & communication | 1986 |
| Bozdag Bakery Ltd | Wholesale & retail | 2025 |
| BP Brokers Ltd | Construction | 2012 |
| Bpcc Property Limited | Real estate | 2020 |
| Bpoc Ltd | Professional & scientific | 2018 |
| BR Autospa Ltd | Administrative & support | 2025 |
| BR Estate Agent Ltd | Real estate | 2020 |
| BR1 Properties Management Ltd | Real estate | 2016 |
| BR1 Software Limited | Information & communication | 2016 |
| BR3 Hand Car Wash Ltd | Wholesale & retail | 2025 |
| BR6 Heating Limited | Construction | 2021 |
| Bracey Films Ltd | Information & communication | 2017 |
| Bradbrook Holdings Ltd | Real estate | 2025 |
| Bradley's Residents Limited | Households | 2021 |
| Braid Bar LDN Ltd | Other services | 2020 |
| Braids and Beyond Services Limited | Other services | 2025 |
| Brainstorm Haze Limited | Health & social care | 2014 |
| Bramble Publishing Limited | Extraterritorial | 1971 |
| Brambledown Management (3/13) Limited | Households | 1972 |
| Bramley Publishing Limited | Information & communication | 1985 |
| Bramleys Admin Limited | Administrative & support | 2016 |
| Bramton Construction Ltd | Construction | 2015 |
| Branchpoint Limited | Real estate | 1980 |
| Brand Operations Limited | Professional & scientific | 2025 |
| Branded Bromley Limited | Hospitality | 2024 |
| Brandhorst Content & Communications Limited | Professional & scientific | 2015 |
| Brandiful Design Ltd | Professional & scientific | 2013 |
| Brandiful Property Limited | Real estate | 2025 |
| Brandriva Ltd | Professional & scientific | 2018 |
| Branscombe Court (Number 2) Management Limited | Households | 1978 |
| Branscombe Court NO 2 Freeholders Limited | Households | 2007 |
| Brasted Lodge Residents Limited | Real estate | 1994 |
| Braundton Consulting Limited | Administrative & support | 2012 |
| Bravada Worldwide Limited | Information & communication | 2017 |
| Braventa Property Holdings Ltd | Real estate | 2026 |
| Bray Financial Limited | Financial services | 2002 |
| Brayground Limited | Construction | 2020 |
| Break OUT Jewellery Limited | Manufacturing | 2021 |
| Breaking Better UK Limited | Public administration | 2022 |
| Breeze Promo Ltd | Professional & scientific | 2019 |
| Breffni Group UK Limited | Construction | 2017 |
| Bremner Property Group Ltd | Real estate | 2024 |
| Brenpower Global Ltd | Information & communication | 2024 |
| Brent Residents Company Limited | Households | 1993 |
| Brewery Village Limited | Construction | 2013 |
| Brian Manktelow Limited | Manufacturing | 1981 |
| Bridge Court (Romford) RTM Company Limited | Real estate | 2014 |
| Bridge to Billionaire Limited | Financial services | 2025 |
| Bridgeforte Healthcare Limited | Transport & logistics | 2025 |
| Bridgen Group Limited | Information & communication | 2024 |
| Bridges Capital Projects Ltd | Real estate | 2023 |
| Bright Child Limited | Education | 2018 |
| Bright Deafblind CIC | Health & social care | 2026 |
| Bright Electrical Contractors N.W Ltd | Real estate | 2011 |
| Bright Match Recruitment Limited | Administrative & support | 2019 |
| Bright Sky Care Ltd | Administrative & support | 2023 |
| Bright Smiles Care Ltd | Health & social care | 2026 |
| BRIGHT10 Ltd | Real estate | 2024 |
| Brightcom Solutions Limited | Professional & scientific | 2024 |
| Brightrose Studio Ltd | Education | 2025 |
| Brightspace Electrical Ltd | Construction | 2015 |
| Brimforce Design Limited | Professional & scientific | 2022 |
| Brink Financial and Accounting Services Ltd | Professional & scientific | 2007 |
| Britain Today Limited | Information & communication | 2020 |
| Britannia IP Limited | Professional & scientific | 2018 |
| Britannia Village (TEN) Residents Management Company Limited | Households | 2000 |
| Britannia Village (Twelve) Residents Management Company Limited | Households | 1999 |
| British Danubian Trade Development Company Limited | Financial services | 1946 |
| British Water Savings Ltd | Construction | 2026 |
| Britrisk Safety Limited | Professional & scientific | 2006 |
| Britton Street Developments Limited | Construction | 2017 |
| Britton Street Properties Limited | Real estate | 2022 |
| Britz Car Parts Ltd | Wholesale & retail | 2025 |
| Brixwell Developments Ltd | Real estate | 2019 |