| Black Gold Nutshell Ltd | Wholesale & retail | 2025 |
| Black River Chocolate Limited | Extraterritorial | 2013 |
| Blackhorse House Management Limited | Households | 2022 |
| BLB Roofing Ltd | Construction | 2024 |
| Blbb Properties Ltd | Real estate | 2019 |
| Blockstar Management Ltd | Professional & scientific | 2025 |
| BLU Nightlife Ltd | Arts & recreation | 2016 |
| Blu-Frog Trading Limited | Wholesale & retail | 2012 |
| Blue Neutrino Ltd | Information & communication | 2025 |
| Blue Whale London Ltd | Financial services | 2015 |
| Bluebrooker Limited | Health & social care | 2020 |
| Bluechestnut Limited | Information & communication | 2014 |
| Bluestone B.M.S. Solutions Ltd | Construction | 2017 |
| BMA Plumbing Ltd | Construction | 2017 |
| BOA Consultants Limited | Professional & scientific | 2013 |
| Boarderline Classic Cards Limited | Administrative & support | 2008 |
| Boating Mania Limited | Wholesale & retail | 1990 |
| BOB Drew Ltd | Professional & scientific | 2024 |
| Bodiam Canine Care Ltd | Other services | 2018 |
| Bodiam Farm Cattery Limited | Other services | 2018 |
| Body and Beauty Ltd | Wholesale & retail | 2024 |
| Bohmen Creative Limited | Administrative & support | 2025 |
| Boilers 4 Essex Ltd | Construction | 2017 |
| Boland Bespoke Limited | Manufacturing | 2025 |
| Boleyn Decorating Company Ltd | Construction | 2016 |
| Bonbella Ltd | Wholesale & retail | 2024 |
| Bondmere and Key Properties Ltd | Real estate | 2025 |
| Bonds Management LLP | | 2025 |
| Boomslang Global Limited | Wholesale & retail | 2024 |
| Boomslang Media Ltd | Other services | 2017 |
| Bordwalk Consulting Ltd | Health & social care | 2022 |
| Bose Franchise Group Ltd | Hospitality | 2026 |
| Botree Nutrition Ltd | Health & social care | 2021 |
| Boveda Shenfield Ltd | Hospitality | 2023 |
| Boyd Close Management Company Limited | Households | 2014 |
| Brackendale SCS Ltd | Professional & scientific | 2016 |
| Bramfitt Technology Labs Limited | Professional & scientific | 2014 |
| Branchfield Ltd | Construction | 2024 |
| Brannon Roofing Services Limited | Construction | 2015 |
| Braycourt Limited | Professional & scientific | 2011 |
| Breakthru Property Services Ltd | Real estate | 2024 |
| Brentwood Hand Car Wash Limited | Wholesale & retail | 2017 |
| Brewis Investments Limited | Real estate | 2021 |
| Brewis Properties Limited | Real estate | 2024 |
| Brian Croker Limited | Real estate | 2013 |
| Brick Lane Bagel Upminster Limited | Hospitality | 2025 |
| Brickfield Hollow Lettings Ltd | Real estate | 2023 |
| Brickhouse Group Ltd | Real estate | 2021 |
| Brickhouse Mortgages Ltd | Financial services | 2020 |
| Bricks & Blocks Ltd | Real estate | 2018 |
| Bridge Avenue Property Limited | Real estate | 2021 |
| Bridge Heating & GAS Services Ltd | Construction | 2009 |
| Bridge Roofing Specialists Limited | Construction | 2022 |
| Bridgerose Construction Ltd | Construction | 2026 |
| Bright INK LAB Ltd | Information & communication | 2018 |
| Brighton Accountants Limited | Professional & scientific | 2014 |
| Brightroc Ltd | Real estate | 2018 |
| Brikco Ltd | Real estate | 2025 |
| Broadsword FX Trading Limited | Financial services | 2014 |
| Brondesbury Accountants Ltd | Professional & scientific | 2016 |
| Brook Electrical Installations Limited | Construction | 2026 |
| Brook Park Developments Essex Ltd | Real estate | 2020 |
| Brothers Spice Limited | Hospitality | 2020 |
| Brownchurch Holdings Limited | Manufacturing | 2001 |
| Brownchurch Ltd | Manufacturing | 1968 |
| Bryanston House Management Company Limited | Households | 2021 |
| BT Project Consultancy Limited | Information & communication | 2015 |
| Buckley & Buckley Properties Limited | Real estate | 2025 |
| Buddies PRE School Limited | Education | 2012 |
| Building Block Projects LLP | | 2008 |
| Building Block Properties (UK) LLP | | 2007 |
| Building Block Properties Limited | Real estate | 2000 |
| Building Energy Management Services Ltd | Manufacturing | 2007 |
| Buildtech Essex Limited | Construction | 2011 |
| Buildtech Security Solutions Ltd | Professional & scientific | 2020 |
| Bujor Carpentry Professional Limited | Construction | 2023 |
| Bulb Electricians Limited | Construction | 2022 |
| Bulb Plumbing and Heating Limited | Construction | 2024 |
| Bullet Property Holdings Ltd | Households | 2021 |
| Buregate House Management Company Limited | Households | 2019 |
| Burning River Ltd | Professional & scientific | 2025 |
| Burrito JOE Limited | Wholesale & retail | 2011 |
| BUS Body Repairs Limited | Manufacturing | 2012 |
| Bush Thermal Services Limited | Construction | 2025 |
| BUYBLISS26 Ltd | Wholesale & retail | 2026 |
| Bysneaks Ltd | Wholesale & retail | 2024 |
| C & V Thomson Limited | Professional & scientific | 2007 |
| C R Smith Consulting Ltd | Professional & scientific | 2024 |
| C W Logistical Consultancy Limited | Professional & scientific | 2017 |
| C Whitcomb Properties Ltd. | Real estate | 2020 |
| C Wiggins Advisory Ltd | Professional & scientific | 2026 |
| C&W Rentals Ltd | Administrative & support | 2013 |
| C&W Transport Limited | Transport & logistics | 2014 |
| C. Ruston & Sons Builders Limited | | 1979 |
| C.E.G. Consultants (Southern) Limited | Administrative & support | 1987 |
| C.K. Bridal Ltd | Wholesale & retail | 2017 |
| C.T. Painters (Essex) Ltd | Construction | 2010 |
| Cadivision Limited | Professional & scientific | 2015 |
| Cafe Baccarat Ltd | Hospitality | 2014 |
| Caffull Ltd | Information & communication | 2011 |