| Black Leaf Build Limited | Construction | 2019 |
| Blackfox Property Management Ltd | Households | 2024 |
| Blackhall Building & Construction Ltd | Construction | 2018 |
| Blackhall Estates Ltd | Real estate | 2020 |
| Blackland Park Exploration Limited | Mining & quarrying | 1985 |
| Blackrock Groundworks Limited | Construction | 2025 |
| Blacks Assets Limited | Real estate | 2023 |
| Blacks Assets SPV Limited | Real estate | 2026 |
| Blackstead Group Holdings Limited | Real estate | 2025 |
| Blackstone Integrated Solutions Limited | Professional & scientific | 2011 |
| Blackthorn Barn Developments Limited | Real estate | 2021 |
| Blackwater Plastics Limited | Manufacturing | 1994 |
| Blackwater Sign and Print Limited | Manufacturing | 2024 |
| Blade Education | Information & communication | 2007 |
| Blake Building & Co Limited | Construction | 2023 |
| Blakemar Properties Limited | Real estate | 2005 |
| Blank Materials Ltd | Construction | 2017 |
| Blaze Films Ltd | Information & communication | 2026 |
| BLB Leigh on Sea Ltd | Hospitality | 2025 |
| BLC Aviation Ltd | Manufacturing | 2024 |
| BLC Consultancy Limited | Professional & scientific | 2019 |
| Bless Leigh Ltd | Hospitality | 2026 |
| Blighloren Limited | Professional & scientific | 2021 |
| Blind Area Technology Ltd | Professional & scientific | 2026 |
| Blink Music Ltd | Information & communication | 2025 |
| Blissful Care Services Ltd | Health & social care | 2021 |
| Blockair Limited | Transport & logistics | 1999 |
| Bloody Realistic Ltd | Education | 2018 |
| Bloom Community Leigh Limited | Education | 2025 |
| Bloreboy Consulting Ltd | Information & communication | 2025 |
| Blossom Property Management Limited | Real estate | 2016 |
| Bloxham Coaching Ltd | Arts & recreation | 2018 |
| Blue Consultants Engineering Limited | Construction | 2024 |
| Blue Door Creative Limited | Information & communication | 2023 |
| Blue EYE Media Limited | Other services | 2024 |
| Blue Group Solutions Ltd | Administrative & support | 2019 |
| Blue Jelly Group Ltd | Information & communication | 2016 |
| Blue Neptune Ltd | Professional & scientific | 2023 |
| Blue Ocean IT Hosting Limited | Other services | 2006 |
| Blue Ocean Studios Ltd | Manufacturing | 2022 |
| Blue Robot.Io Limited | Wholesale & retail | 2021 |
| Blue Rocque Ltd | Professional & scientific | 2016 |
| Blue Sarabbie Holdings Ltd | Administrative & support | 2022 |
| Blue Stag Landscapes Limited | Administrative & support | 2023 |
| Blue Stag Property Maintenance Limited | Construction | 2024 |
| Blue Tractor (UK) Limited | Administrative & support | 2015 |
| Blue Tractor Australasia Limited | Administrative & support | 2022 |
| Blue Tractor Elite Limited | Administrative & support | 2022 |
| Blue Tractor Europa Limited | Administrative & support | 2023 |
| Blue Tractor Financial Solutions Limited | Administrative & support | 2023 |
| Bluebell Maldon Ltd | Administrative & support | 2017 |
| Bluebird Management and Consultancy Limited | Professional & scientific | 2015 |
| Bluemont Innovations Ltd | Wholesale & retail | 2025 |
| Bluepoint Construction Ltd | Construction | 2022 |
| Bluepoint Developments Ltd | Construction | 2022 |
| Bluepoint Global Ltd | Construction | 2022 |
| Bluepoint Homes Ltd | Real estate | 2020 |
| Bluesea Technology Ltd | Information & communication | 2020 |
| Bluesky Property Investment Limited | Real estate | 2007 |
| Bluetoy Limited | Wholesale & retail | 2016 |
| Blush Bridal Gowns Ltd | Wholesale & retail | 2024 |
| BLW Southeast Ltd | Construction | 2023 |
| BMB Project Management Limited | Professional & scientific | 2025 |
| BMC (Grays) Ltd | Wholesale & retail | 2015 |
| BMC Recruitment & Hire Limited | Construction | 2024 |
| BMR Classic Ltd | Wholesale & retail | 2024 |
| BMR Performance (Sussex) LLP | | 2024 |
| BMR Performance Ltd | Wholesale & retail | 2017 |
| BNB Leigh Limited | Wholesale & retail | 2023 |
| BNM (Essex) Limited | Extraterritorial | 2018 |
| Boba Boulevard Leigh Ltd | Hospitality | 2025 |
| Bobby Moore Enterprises Ltd | Professional & scientific | 2021 |
| Bocca Social Ltd | Hospitality | 2017 |
| Boccaccio Holdings Ltd | Real estate | 2026 |
| Bodybyjr Ltd | Education | 2018 |
| Bodyrite Contour Limited | Other services | 2016 |
| Boesch Medical Services Limited | Health & social care | 2013 |
| Bogazici Ltd | Hospitality | 2025 |
| Boisere Holdings Limited | Financial services | 2025 |
| Bombarde Investments Ltd | Real estate | 2018 |
| Bond Fire Protection Service Limited | Manufacturing | 2001 |
| Bondlabels Limited | Manufacturing | 1983 |
| Book My Stay Group Limited | Financial services | 2026 |
| Book My Stay Limited | Administrative & support | 2025 |
| Book My Trade Stay Limited | Administrative & support | 2025 |
| Borehams Environmental Ltd | Water & waste | 2020 |
| Boudoir Property Limited | Real estate | 2024 |
| Boulevard Leisure Ltd | Arts & recreation | 2026 |
| Bouxbi Ltd | Wholesale & retail | 2026 |
| Bowinger Ltd. | Information & communication | 2011 |
| Bowstone Leisure & Building Limited | Administrative & support | 1995 |
| Bowtieteacher Limited | Education | 2024 |
| Box Storage NE Ltd | Real estate | 2024 |
| Boxted Management Ltd | Real estate | 2023 |
| Bozloc Limited | Information & communication | 2022 |
| BP (Essex) Ltd | Extraterritorial | 2018 |
| BP (Langdon) Ltd | Extraterritorial | 2019 |
| BPO Technology Ltd. | Information & communication | 2015 |
| Bracken Building Consultancy Ltd | Professional & scientific | 2021 |
| Bradcombe Management Limited | Households | 1986 |