| Body Base Limited | Health & social care | 2011 |
| Body Happy Ltd | Arts & recreation | 2017 |
| Body Rehab Studios Ltd | Health & social care | 2007 |
| Boingboing Foundation | Professional & scientific | 2021 |
| Boingboing Resilience CIC | Professional & scientific | 2010 |
| BOJ & Buddies Limited | Information & communication | 2012 |
| BOJ Brothers Limited | Real estate | 2023 |
| Bolivar Property Ltd | Real estate | 2022 |
| Bolton Clarke Limited | Administrative & support | 2010 |
| Bombetta London Ltd | Hospitality | 2015 |
| Bombus Media Group Ltd | Information & communication | 2022 |
| BON & MUM Ltd | Hospitality | 2019 |
| Bondinvest Capital Limited | Financial services | 2017 |
| Bone 2025 Ltd | Hospitality | 2025 |
| Bonner Chiropody Service Ltd | Health & social care | 2003 |
| Bonnie Property Ltd | Real estate | 2023 |
| BOO Tickety Ltd | Professional & scientific | 2022 |
| Booband Limited | Other services | 2015 |
| Boobuddy Limited | Wholesale & retail | 2017 |
| Boomtill Limited | Households | 1998 |
| Boomzone Ltd | Real estate | 2016 |
| Boot Room TV Limited | Information & communication | 2008 |
| Boothby Solar Limited | Energy | 2013 |
| Borderfree Trade Limited | Administrative & support | 2012 |
| Boretech Engineering Ltd | Wholesale & retail | 2009 |
| Born Lucky Inc Ltd | Administrative & support | 2015 |
| Borough Gate Management (Steyning) Limited | Households | 2006 |
| Borrie-Bonell Investment Company,Limited | Financial services | 1951 |
| Bosphorus Group Ltd | Construction | 2021 |
| Boss & Co Property Ltd | Construction | 2023 |
| Boss Property Management Ltd. | Households | 2020 |
| Bostal Limited | Arts & recreation | 2025 |
| Botolph Consulting Limited | Professional & scientific | 2026 |
| Boughton Properties Sussex Limited | Real estate | 2025 |
| Boundary D.I.Y. Limited | Real estate | 2004 |
| BOW Trading Limited | Wholesale & retail | 2015 |
| Bowden Property Consulting Limited | Administrative & support | 2006 |
| Bowen Court Limited | Households | 1986 |
| Bowline Point RTM Company Limited | Households | 2012 |
| Bowood Accountancy Services Ltd | Professional & scientific | 2016 |
| Box N Burn Limited | Arts & recreation | 2025 |
| Boxgrove Properties Limited | Construction | 1996 |
| Boxleaf Ltd | Real estate | 2020 |
| Boydonegood Ltd | Professional & scientific | 2016 |
| Boysterous Burger Ltd | Hospitality | 2025 |
| Boytonlynn Properties Limited | Households | 1983 |
| Bozwell Media Limited | Information & communication | 2015 |
| BPM2 Ltd | Construction | 2020 |
| BPO Search Limited | Other services | 2023 |
| Bradbeech Limited | Households | 1982 |
| Bradbury Hamilton Limited | Financial services | 1993 |
| Bradley Solar Limited | Energy | 2013 |
| Brads Woodcraft Limited | Manufacturing | 2022 |
| Bradwell Technologies Ltd | Information & communication | 2009 |
| Brainerd Limited | Health & social care | 2003 |
| Bramham Limited | Real estate | 2020 |
| Brand Essential Limited | Wholesale & retail | 2026 |
| Brandonharris Limited | Other services | 2020 |
| Brandrock Limited | Professional & scientific | 2021 |
| Brantbourne Holiday Lettings Limited | Hospitality | 2017 |
| Brantbourne Properties Limited | Real estate | 2017 |
| Brasserie Coastal Ltd | Hospitality | 2025 |
| Brave Blossom Ltd | Professional & scientific | 2023 |
| Brave Events UK Ltd | Professional & scientific | 2020 |
| Bravery Care Limited | Health & social care | 2018 |
| Bravery Properties Limited | Real estate | 2018 |
| Bread and Butter BTN Ltd | Professional & scientific | 2025 |
| Breakwater BN3 Ltd | Wholesale & retail | 2021 |
| Breathe to BE YOU Ltd | Extraterritorial | 2024 |
| Breeze AC Ltd | Construction | 2023 |
| Brennan Herriott & Co Ltd | Professional & scientific | 2015 |
| Brew Minder Ltd | Wholesale & retail | 2019 |
| Brewery Mews Management Company Limited | Households | 2005 |
| Bri'Elle Rose Consulting Ltd | Professional & scientific | 2019 |
| Bri-Tek Construction Limited | Construction | 2006 |
| Brian Mackrell & Co Ltd | Professional & scientific | 2003 |
| Brian Mason Technology Limited | Professional & scientific | 2002 |
| Briant Communications Limited | Wholesale & retail | 1992 |
| Bridbeech Limited | Real estate | 1979 |
| Bridea Limited | Professional & scientific | 2013 |
| Bridgetown Finance Ltd | Real estate | 2010 |
| Bridgetown Properties Ltd | Real estate | 2010 |
| Bridgetutors Limited | Education | 2023 |
| Brigadoon Dental Limited | Health & social care | 2026 |
| Briggs & Briggs LLP | | 2017 |
| Briggs Company (Southern) Ltd | Administrative & support | 2021 |
| Bright & Shade Group Limited | Construction | 2002 |
| Bright Build (Sussex) Ltd | Manufacturing | 2026 |
| Bright Cocktail Co Ltd | Wholesale & retail | 2021 |
| Bright Creation Limited | Professional & scientific | 2006 |
| Bright Dental Clinic Limited | Health & social care | 2008 |
| Bright Dials Limited | Professional & scientific | 2018 |
| Bright Echo Ltd | Professional & scientific | 2024 |
| Bright International Education Ltd | Education | 2017 |
| Bright N Shine Cleaning Services Ltd | Administrative & support | 2016 |
| Bright Orange Services Ltd | Professional & scientific | 2023 |
| Bright OWL Digital Limited | Information & communication | 2016 |
| Bright Red Lips Ltd | Professional & scientific | 2023 |
| Bright Shore Ltd | Construction | 2023 |
| Bright Smile (UK) Limited | Health & social care | 2006 |