| Brighter Connect Limited | Professional & scientific | 2014 |
| Brighter Days Ltd | Other services | 2022 |
| Brignall Management Limited | Households | 2006 |
| Brilliant IT Ltd | Information & communication | 2020 |
| Brimah and John Ltd | Professional & scientific | 2021 |
| Briquelife UK Limited | Real estate | 2023 |
| Brish Group Limited | Water & waste | 2026 |
| Brish Wood Recycling Ltd | Water & waste | 2023 |
| Brisk Properties Limited | Real estate | 2021 |
| Brisqmoney Limited | Information & communication | 2025 |
| Brisqnet Limited | Information & communication | 2025 |
| Britagro Limited | Agriculture & fishing | 2024 |
| Britannia Gate Management Company Limited | Households | 2014 |
| Britannia Lake View Residents RTM Company Limited | Households | 2023 |
| Britannia Residents Management Company Limited | Households | 2017 |
| Britannia Village (Four) Residents Management Company Limited | Households | 1998 |
| Britannia Village (One) Residents Management Company Limited | Households | 1996 |
| Britannia Village (Seven) Residents Management Company Limited | Households | 2000 |
| Britannia Village (SIX) Residents Management Company Limited | Households | 1998 |
| Britannia Village (Three) Residents Management Company Limited | Households | 1998 |
| Britannia Village General Management Company Limited | Households | 1996 |
| Britbridge Partners Ltd | Professional & scientific | 2025 |
| Briteat Ltd | Information & communication | 2024 |
| Broad Oaks Management Co. Limited | Households | 1993 |
| Broadacre Farming Partners LLP | | 2015 |
| Broadfield Security & Services Ltd | Professional & scientific | 2020 |
| Broadway Group Ltd | Construction | 2017 |
| Brobot Technologies Limited | Information & communication | 2025 |
| Brockley Homes 1 Ltd | Construction | 2018 |
| Brockley Homes 2 Ltd | Real estate | 2019 |
| Brockley Homes 3 Ltd | Real estate | 2019 |
| Brockley Homes 5 Ltd | Construction | 2020 |
| Brockley Homes 7 Ltd | Real estate | 2020 |
| Brockley Homes Ltd | Construction | 2019 |
| Broga Solutions Ltd | Information & communication | 2025 |
| Brondeswell Court Limited | Households | 2006 |
| Brookbay Property Ltd | Real estate | 2024 |
| Brooke and Co Accounting Ltd | Professional & scientific | 2025 |
| Brooker Road Investment Ltd | Real estate | 2025 |
| Brookside Meadows Residents Management Company Limited | Households | 2024 |
| Broom Street Shop Ltd | Information & communication | 2025 |
| Broomfield & Anderson Limited | Construction | 2000 |
| Broomsleigh Properties Ltd | Financial services | 2021 |
| Brother's Cafe Ltd | Hospitality | 2024 |
| Brou Estates Ltd | Real estate | 2025 |
| Brownies N Shakes Ltd | Hospitality | 2022 |
| Bruce Cleaning Services Limited | Administrative & support | 1981 |
| Bruce Maintenance Services Limited | Administrative & support | 1988 |
| Brunswick Terrace Management Company Number 2 Limited | Real estate | 2011 |
| Bryleigh Social Ltd | Professional & scientific | 2026 |
| Bryson GAS Ltd | Other services | 2018 |
| BS Harlow Ltd | Hospitality | 2024 |
| BS Ventures Limited | Professional & scientific | 2021 |
| Bsap Regimental Association United Kingdom Branch | Other services | 2019 |
| Bsav Consultants Limited | Administrative & support | 2014 |
| BSC Contracts Ltd | Manufacturing | 2013 |
| BSC Valeting and Detailing Ltd | Administrative & support | 2025 |
| Bscb Electrical Limited | Construction | 2024 |
| Bsir Limited | Construction | 2015 |
| Btech Harlow Repair Ltd | Wholesale & retail | 2024 |
| Btmakamah Limited | Health & social care | 2026 |
| BTN Crew Ltd | Arts & recreation | 2019 |
| Btzs Properties Ltd | Real estate | 2025 |
| Bubzee Corp Limited | Information & communication | 2025 |
| Bubzee Enterprises Ltd | Wholesale & retail | 2025 |
| Buch Trans Limited | Transport & logistics | 2018 |
| Buchan Close Management Limited | Households | 2023 |
| Bucklebury Heath Management Association Limited | Households | 1986 |
| Buffalo Floors Ltd | Wholesale & retail | 2025 |
| Build Tech Facilities Services Ltd | Construction | 2026 |
| Build UP General Construction Ltd | Construction | 2021 |
| Builders Pro Ltd | Construction | 2024 |
| Buildmit Limited | Administrative & support | 2011 |
| Buildwright Construction Ltd | Construction | 2021 |
| Built by Content Ltd | Information & communication | 2016 |
| Built With a View Limited | Construction | 2023 |
| Bukkyslayedit Limited | Other services | 2023 |
| Bulford Properties Ltd | Real estate | 2004 |
| Bulgaria Ltd | Manufacturing | 2007 |
| Bullbridge Management Company (Belper) Limited | Real estate | 2022 |
| Buntingford Heating Ltd | Construction | 2018 |
| Bunyoro Investments Group Limited | Real estate | 2021 |
| Burbosa Ltd | Wholesale & retail | 2021 |
| Burch First AID Ltd | Education | 2020 |
| Burlington Place 1 (Foxton) Management Company Limited | Households | 2020 |
| Burnt Mill (Harlow) LLP | | 2024 |
| Burra Creative Ltd | Professional & scientific | 2020 |
| Burton Joinery (Construction) Limited | Manufacturing | 1984 |
| Burton Laminates Limited | Manufacturing | 2000 |
| Bush Fair Management Limited | Administrative & support | 1987 |
| Bushfair Limited | Hospitality | 2024 |
| Busy Cleaning Bees Ltd | Administrative & support | 2019 |
| Butt Traders Limited | Hospitality | 2025 |
| Button Freehold Ltd | Households | 2023 |
| Buzzee Beez Pre-School Limited | Education | 2009 |
| BW Property Solutions Ltd | Administrative & support | 2015 |
| BY Elizabeth Ltd | Other services | 2020 |
| BY the Sea Management Ltd | Arts & recreation | 2024 |
| Byewaters (NO.3) Apartment Management Company Limited | Households | 1998 |
| Byil Limited | Real estate | 2022 |