| Bleue Heron Limited | Administrative & support | 2023 |
| BLG Engineering Limited | Construction | 2025 |
| Blind Burners Community Interest Company | Information & communication | 2022 |
| Blind Justice C.I.C. | Public administration | 2025 |
| Blindoctopus Ltd | Hospitality | 2019 |
| Blindsquid Ltd | Other services | 2022 |
| Blisstopia Productions Ltd | Other services | 2015 |
| Blisswell Limited | Households | 2019 |
| Blitz Events Limited | Arts & recreation | 2024 |
| Blitz Taxi Ltd | Transport & logistics | 2025 |
| Bljr Properties Limited | Real estate | 2019 |
| Block D Limited | Households | 2023 |
| Blockhead Group Ltd | Construction | 2019 |
| Blond Bombshell Media Limited | Information & communication | 2025 |
| Blons Motorcycles Ltd | Wholesale & retail | 2023 |
| Bloom Advisory Limited | Professional & scientific | 2026 |
| Bloom Coaching & Consulting Ltd | Professional & scientific | 2022 |
| Bloom Media Group Ltd | Professional & scientific | 2024 |
| Bloom Media Solutions Ltd | Information & communication | 2024 |
| Bloomfield Brighton LLP | | 2015 |
| Blooming Bookkeeping Services Ltd | Professional & scientific | 2023 |
| Blossomlifestyle Limited | Wholesale & retail | 2023 |
| Blount Construction Limited | Construction | 2021 |
| Blow Your Top (Brighton) Ltd. | Other services | 2003 |
| Blox Software Ltd | Information & communication | 2022 |
| BLS Sussex Limited | Real estate | 2018 |
| BLU3PR1N7 Limited | Other services | 2018 |
| Blue 14 (D2C) Ltd | Wholesale & retail | 2018 |
| Blue and White Capital Limited | Professional & scientific | 2015 |
| Blue Bird Electrical Services Ltd | Construction | 2014 |
| Blue Bird Food Ltd | Hospitality | 2022 |
| Blue Buddies Ltd | Administrative & support | 2025 |
| Blue Co International LLP | | 2011 |
| Blue Co London LLP | | 2011 |
| Blue Day Digital Ltd | Information & communication | 2024 |
| Blue Diamond International Holdings Limited | Real estate | 2021 |
| Blue Diamonds of London Ltd | Manufacturing | 2021 |
| Blue Door Holdings Group Limited | Financial services | 2024 |
| Blue Door Praxis Ltd | Professional & scientific | 2026 |
| Blue Dorsal Projects Limited | Information & communication | 2019 |
| Blue Dorsal Properties Limited | Financial services | 2020 |
| Blue Edge Security Limited | Administrative & support | 2025 |
| Blue Giraffe Property Limited | Construction | 2019 |
| Blue Goose Pubs Ltd | Hospitality | 2022 |
| Blue Hawaiian Limited | Hospitality | 2021 |
| Blue Home Estate Agents Limited | Real estate | 2024 |
| Blue HUE Ltd | Information & communication | 2026 |
| Blue International Services Limited | Professional & scientific | 1995 |
| Blue Kingdom Investments (One) Limited | Real estate | 2023 |
| Blue Lemon Enterprise Limited | Other services | 2015 |
| Blue Light Films Ltd | Information & communication | 2025 |
| Blue Lion Plant Limited | Construction | 2007 |
| Blue Lizard Consulting Investments Limited | Financial services | 2012 |
| Blue Lizard Consulting Limited | Real estate | 2001 |
| Blue Lizard Consulting Services Limited | Professional & scientific | 2024 |
| Blue MAN Ltd | Hospitality | 2024 |
| Blue Marble IT Ltd | Information & communication | 2025 |
| Blue Nile South Ltd | Hospitality | 2020 |
| Blue Panda Marketing Limited | Professional & scientific | 2023 |
| Blue Pepper Productions Limited | Information & communication | 2013 |
| Blue Portslade Limited | Hospitality | 2019 |
| Blue Rise Horizon Ltd | Real estate | 2020 |
| Blue Sail Consulting Limited | Professional & scientific | 2006 |
| Blue Sea Assets Ltd | Other services | 2016 |
| Blue Sea Projects Ltd | Construction | 2025 |
| Blue Skies Window Cleaning Limited | Administrative & support | 2015 |
| Blue Sky Dental Limited | Health & social care | 2016 |
| Blue Star Capital PLC | Administrative & support | 2004 |
| Blue Stone 2025 Ltd | Real estate | 2025 |
| Blue Stone 24 Ltd | Financial services | 2024 |
| Blue Stone 57 Limited | Construction | 2006 |
| Blue Surge Ltd | Professional & scientific | 2024 |
| Blue Tiger Psychology Group Ltd | Health & social care | 2022 |
| Blue Wave Cleaning Ltd | Administrative & support | 2025 |
| Blue Yonder 1 Ltd | Real estate | 2024 |
| Blueberri Limited | Hospitality | 2012 |
| Bluebird IT Consultancy Limited | Information & communication | 2017 |
| Bluecar Vehicles Ltd | Wholesale & retail | 2025 |
| Bluefin Automations Ltd | Professional & scientific | 2024 |
| Bluehaze Freehold Company Limited | Households | 2022 |
| Bluemay Marketing Limited | Wholesale & retail | 2021 |
| Blueneon Consultants Limited | Information & communication | 2013 |
| Blueprint Coaching & Training Ltd | Professional & scientific | 2013 |
| Blueprint Digital Consulting Ltd | Information & communication | 2024 |
| Blueprint Music Group Ltd | Information & communication | 2022 |
| Blueprint Project Management Ltd | Construction | 2020 |
| Bluesky Energy Solutions Limited | Construction | 2019 |
| Bluestone Property Developments Limited | Construction | 2016 |
| Bluestoneuk Limited | Real estate | 2019 |
| Bluestorm Limited | Households | 1998 |
| Bluewater Property Ltd | Real estate | 2025 |
| Blushed Brighton Ltd | Other services | 2022 |
| BM GAS Services Limited | Construction | 2019 |
| BM3 Trading Ltd | Transport & logistics | 2025 |
| Bmac International Trade Ltd | Wholesale & retail | 2021 |
| Bmal Consulting Ltd | Professional & scientific | 2022 |
| Bmdm Events and Media Limited | Arts & recreation | 2019 |
| BN Bespoke Carpentry & Renovations Limited | Construction | 2025 |
| BN Fire & Security Ltd | Construction | 2025 |
| BN Home Surveys Ltd | Professional & scientific | 2026 |