| Blue Circle Surveyors Ltd | Professional & scientific | 2024 |
| Blue EGG Services Limited | Construction | 2022 |
| Blue Leaf Rentals Ltd | Administrative & support | 2025 |
| Blue Ocean Yacht Supplies Ltd | Wholesale & retail | 2022 |
| Blue PIP Tech Ltd | Administrative & support | 2024 |
| Blue Star Scaffolding Ltd | Construction | 2024 |
| Blueicen Limited | Construction | 2011 |
| Bluewater Property DEV Ltd | Real estate | 2017 |
| BM Rigging Limited | Arts & recreation | 2012 |
| BMG Southeast Ltd | Construction | 2026 |
| BML Construction Ltd | Construction | 2025 |
| BN Fabrication Ltd | Manufacturing | 2026 |
| BNO Consultants Limited | Information & communication | 2019 |
| BOD Building Contractors Services Ltd | Construction | 2025 |
| BOF Consulting Ltd | Professional & scientific | 2023 |
| Boh&S Ltd | Professional & scientific | 2005 |
| Boho Drinks Brands Ltd | Manufacturing | 2017 |
| Boho Drinks Ltd | Manufacturing | 2017 |
| Boleyn Court Management Limited | Households | 1988 |
| Boltvaultuk Ltd | Energy | 2024 |
| Bomepp Limited | Financial services | 2013 |
| BON BON Fistral Ltd | Wholesale & retail | 2026 |
| Bond Built on Design Limited | Construction | 2024 |
| Bondi Coffee Limited | Wholesale & retail | 2017 |
| Booked N Paid UK Limited | Education | 2025 |
| Boolol Holdings Ltd | Real estate | 2025 |
| Bordeaux Vintners Limited | Wholesale & retail | 2010 |
| Borden Jaya Limited | Hospitality | 2023 |
| Boreham and George Limited | Real estate | 2025 |
| Born to Ltd | Health & social care | 2020 |
| Boss EFE Ltd | Other services | 2026 |
| Bossbabecollection Ltd | Wholesale & retail | 2020 |
| BOW WOW Doggy Day Care Limited | Other services | 2016 |
| Boxedwithlove Ltd | Wholesale & retail | 2025 |
| BP Civils Ltd | Construction | 2017 |
| BPI Consultants Ltd | Professional & scientific | 2012 |
| BPP Cables Limited | Professional & scientific | 2010 |
| Bpsl Limited | Extraterritorial | 2022 |
| BPT GAS Services Limited | Construction | 2015 |
| BPW Solutions Ltd | Construction | 2024 |
| Bracci Mortgage and Protection Services Limited | Financial services | 2021 |
| Bradleys Fencing Limited | Construction | 2014 |
| Braide Park Interiors Limited | Professional & scientific | 2025 |
| Braithwaite Investment Partners LLP | | 2020 |
| Bramble Hall LLP | | 2025 |
| Brandon Brothers Estates Limited | Real estate | 2026 |
| Bray Resolutions Ltd | Professional & scientific | 2024 |
| Brayers Properties Limited | Real estate | 2022 |
| Breakwater Cafe Limited | Wholesale & retail | 2017 |
| Brett Zealey Office Solutions Ltd | Administrative & support | 2010 |
| Bretter Properties Ltd | Real estate | 2021 |
| Brew and Chew Limited | Hospitality | 2026 |
| BRF Property Management Ltd | Real estate | 2023 |
| Brick House Moulds Ltd | Other services | 1998 |
| Bridge Business Development Limited | Information & communication | 2024 |
| Bridgewater Recruitment Ltd | Administrative & support | 2016 |
| Bridging Families C.I.C. | Education | 2014 |
| Bright Futures Care Services Ltd | Health & social care | 2026 |
| Bright Horizon Consultancy Services Limited | Administrative & support | 2017 |
| Bright Lark IT Ltd | Information & communication | 2020 |
| Briskrange Limited | | 1978 |
| Bristol Property Services Ltd | Construction | 2020 |
| Britannia Hoist & Lifting Services Limited | Construction | 2025 |
| BRO Code Limited | Wholesale & retail | 2023 |
| Bronze Body Care Centre Limited | Other services | 2006 |
| Brooke-Hall Construction Limited | Construction | 1994 |
| Brooke-Hall Developments Limited | Construction | 2008 |
| Brooke-Hall Holdings Limited | Construction | 2008 |
| Brookes Fencing Limited | Construction | 2015 |
| Brooksair Ltd | Construction | 2025 |
| Brooms Professional Services Limited | Professional & scientific | 2006 |
| Brothers Drain Services Ltd | Water & waste | 2016 |
| Brothers Maintenance Services Ltd | Water & waste | 2023 |
| Browns Properties (Essex) Ltd | Real estate | 2017 |
| Browns Solicitors (Essex) Ltd | Professional & scientific | 2014 |
| BS Autoshine Ltd | Administrative & support | 2025 |
| Bsol 2019 Ltd | Manufacturing | 2019 |
| BTD Media Productions Limited | Information & communication | 2022 |
| BTW Building & Maintenance Limited | Construction | 2014 |
| Bubble N Bounce Ltd | Other services | 2021 |
| Bubble on CUP Ltd | Hospitality | 2024 |
| Buckland Park Management Ltd | Households | 2006 |
| Buckley, Smith & Partners Limited | Real estate | 1996 |
| Buff 'N' Fluff Limited | Hospitality | 2026 |
| Buffs Hair & Beauty Bar Limited | Other services | 2018 |
| Build Automation Ltd | Professional & scientific | 2021 |
| Build Essex Ltd | Construction | 2014 |
| Building Facilities Management Limited | Construction | 2020 |
| Built Bespoke Carpentry & Joinery Limited | Construction | 2022 |
| Bulldog Event Medical Services Ltd | Health & social care | 2025 |
| Bunny and TAZ Limited | Real estate | 2022 |
| Burling Building Services Ltd | Construction | 2015 |
| Burnett Construction Limited | Construction | 2022 |
| Burnett Developments Limited | Real estate | 2022 |
| Burnett Property Rentals Limited | Real estate | 2023 |
| Burnieco Properties Ltd | Real estate | 2017 |
| Burwood Building Services Ltd | Construction | 2026 |
| Burwood’S Property Developers Ltd | Construction | 2025 |
| Bury Construction Ltd | Construction | 2024 |
| Business Defence Systems Ltd | Information & communication | 2020 |