| B-Prepared Flooring Ltd | Construction | 2024 |
| B. Barnes Decorators Ltd | Construction | 2020 |
| B. Gilders Limited | Construction | 2004 |
| B. Plumley Limited | Agriculture & fishing | 1954 |
| B. Roberts Equity Trading Ltd | Financial services | 2012 |
| B.A.T. Financial Services LLP | | 2009 |
| B.I.D Carpentry Ltd | Construction | 2019 |
| B.I.G. (Brackets and Bolts) Limited | Manufacturing | 2000 |
| B.J. Cadman Developments Limited | Real estate | 1991 |
| B.J. Cadman Holdings Limited | Real estate | 1990 |
| B.J. Cadman Investments Limited | Financial services | 2025 |
| B.J. Cadman Properties Limited | Financial services | 2025 |
| B1 Essex Property Limited | Real estate | 2019 |
| B1 Property Investment Ltd | Real estate | 2019 |
| B2BRAFFLES Ltd | Arts & recreation | 2025 |
| B2R Ventures Limited | Wholesale & retail | 2025 |
| B3 Architects Limited | Professional & scientific | 2016 |
| B4SECURE Limited | Information & communication | 2016 |
| BAA Groundcare Ltd | Administrative & support | 2021 |
| Babaire Limited | Health & social care | 2016 |
| Babako GB Ltd | Transport & logistics | 2020 |
| Babas D&B Bar Ltd | Hospitality | 2024 |
| Babbs Building Ltd | Construction | 2026 |
| Baby Centre Ltd | Wholesale & retail | 2020 |
| Babylon FRI Ltd | Construction | 2025 |
| Back Lane Mews Limited | Construction | 2025 |
| Back-Up Planning Services Limited | Professional & scientific | 1994 |
| Backdrop Promotions Limited | Other services | 2018 |
| Backseat Drivers Ltd | Arts & recreation | 2025 |
| Backtrack Systems Limited | Extraterritorial | 2007 |
| Backyard Technologies Limited | Information & communication | 2024 |
| Bacon & Elms Ltd | Manufacturing | 2024 |
| Bacons Golf Yard Ltd | Wholesale & retail | 2024 |
| Bacs Fire Safety Ltd | Financial services | 2025 |
| Bacton SPV Ltd | Construction | 2023 |
| BAF Management Limited | Transport & logistics | 2018 |
| Bafor Property Limited | Real estate | 2016 |
| Bagel Bar Ltd | Other services | 2017 |
| Baggage Repairs Ltd | Information & communication | 2026 |
| Bahe Design Ltd | Wholesale & retail | 2020 |
| Bailand Construction Limited | Construction | 2015 |
| Bailey Change Services Ltd | Professional & scientific | 2025 |
| Bailey Howe Construction Planning Ltd | Construction | 2025 |
| Bailey Lawrence Developments Limited | Real estate | 2021 |
| Bajgni Group Ltd | Professional & scientific | 2025 |
| Bajwa Property Management Ltd | Real estate | 2025 |
| Bake & Beyond Cafe and Bar Limited | Hospitality | 2025 |
| Baked by Jodi Ltd | Wholesale & retail | 2026 |
| Bakedo Ltd | Manufacturing | 2024 |
| Bakeoffee Ltd | Hospitality | 2013 |
| Baker Mackay Whittle Limited | Real estate | 2022 |
| Baker Professional Services Limited | Administrative & support | 2025 |
| Bakerbyte Ltd | Information & communication | 2025 |
| Bakers Court (Colchester) Management Company Ltd | Households | 2001 |
| Bakers Court Freehold Company Limited | Households | 2002 |
| Bakers Delight Ipswich Limited | Professional & scientific | 2005 |
| Bakers Lofts Ltd | Construction | 2018 |
| Balanced YOU Nutrition Ltd | Health & social care | 2019 |
| Balancing ACT Bookkeeping Limited | Information & communication | 2006 |
| Balasundri Metals Limited | Wholesale & retail | 2016 |
| Baldwin Scaffolding Management Ltd | Construction | 2022 |
| Baldwins of Brightlingsea Ltd | Wholesale & retail | 2023 |
| Baldwins of Mersea Limited | Wholesale & retail | 2021 |
| Balearic Property Limited | Real estate | 2019 |
| Balgownie 7 Limited | Households | 2020 |
| Balkerne Gate Developments (East Anglia) Ltd | Construction | 2017 |
| Balkerne Gate Developments (South East) Limited | Construction | 2015 |
| Balkerne Gate Investments Ltd | Construction | 2023 |
| Balkerne Gate Properties Limited | Construction | 2021 |
| Balkerne Property Limited | Real estate | 2025 |
| Ball Hall (Project Management) Ltd | Professional & scientific | 2012 |
| Ballari Ghosh Ltd | Health & social care | 2023 |
| Balls Farm Ltd | Real estate | 2004 |
| Ballyhoo Creative Limited | Professional & scientific | 2006 |
| Baltika Worldwide Ltd | Wholesale & retail | 2013 |
| Bamburgh House Ltd | Health & social care | 2013 |
| Bamsie Limited | Information & communication | 2022 |
| Bana Water Ltd | Manufacturing | 2024 |
| Bandall Ltd | Information & communication | 2022 |
| Bandicoot Holdings Ltd | Professional & scientific | 2021 |
| Bangal Curry House Ltd | Hospitality | 2025 |
| Bangladeshi Women's Association Essex (Bwae) CIC | Administrative & support | 2019 |
| Bani Staffing Ltd | Administrative & support | 2024 |
| Banji Bro's Limited | Real estate | 2025 |
| Banks Bros. LLP | | 2012 |
| Bankside Estate Management Company Limited | Real estate | 2016 |
| Banmar Limited | Administrative & support | 2019 |
| Banniuk FPV Futures Limited | Arts & recreation | 2016 |
| Bantaba Express Ltd | Administrative & support | 2017 |
| Banwatch Solutions Ltd | Information & communication | 2008 |
| BAP Business Solutions Ltd | Information & communication | 2014 |
| Bar and Club Management Ltd | Hospitality | 2019 |
| Barakah Indian Takeway Ltd | Hospitality | 2026 |
| Barberpod (Colchester) Limited | Wholesale & retail | 2020 |
| Barclay Gifford Associates Limited | Extraterritorial | 2002 |
| Barclay Penny Training Co. Limited | Education | 2017 |
| Bardol Construction Limited | Construction | 2019 |
| Bare & Blank Ltd | Health & social care | 2024 |
| Bare Method Academy Limited | Education | 2026 |
| Bare Native Ltd | Manufacturing | 2019 |