| Brewster Motors (Essex) Limited | Wholesale & retail | 1966 |
| BRF Global Ltd | Wholesale & retail | 2025 |
| Bri-Scott Limited | Transport & logistics | 2019 |
| Brian Clark Contractors Limited | Construction | 2002 |
| Brian W. Cornwell Limited | Construction | 1978 |
| Brick Barns Farms Limited | Agriculture & fishing | 1960 |
| Bricktopia Ltd | Wholesale & retail | 2021 |
| Bridge Academy Trust | Education | 2011 |
| Bridge Finance Limited | Financial services | 2013 |
| Bridgeport Holdings Limited | Financial services | 2021 |
| Bridgeways Properties Limited | Professional & scientific | 1996 |
| Bridgewick Developments Ltd | Construction | 2018 |
| Bridgewick Partners Limited | Administrative & support | 2025 |
| Briggs & Stratton U.K. Limited | Wholesale & retail | 1986 |
| Bright Accounting Services Limited | Professional & scientific | 2015 |
| Bright Foods Ltd | Wholesale & retail | 2023 |
| Bright Future Mortgages Ltd | Financial services | 2023 |
| Bright Green Shoots Ltd | Professional & scientific | 2009 |
| Bright Land Development Ltd | Real estate | 2026 |
| Bright Path Admin Services Ltd | Administrative & support | 2025 |
| Brightday Retail Limited | Wholesale & retail | 2022 |
| Brightdayhealthcare.Com Ltd | Health & social care | 2021 |
| Brighter Daily Cleaning Group Limited | Administrative & support | 2020 |
| Brighterdays.Life Ltd | Other services | 2023 |
| Brightling Group Limited | Administrative & support | 2020 |
| Brimchall Limited | Real estate | 2011 |
| Brinkworth Developments Ltd | Real estate | 2018 |
| Brisca Healthcare Ltd | Health & social care | 2014 |
| Brit Auto Hub Limited | Wholesale & retail | 2026 |
| Brit Customs Ltd | Transport & logistics | 2021 |
| Brit Farms Limited | Wholesale & retail | 2021 |
| Britannia Lightspeed Technologies Limited | Information & communication | 2020 |
| Britespark East Limited | Information & communication | 2017 |
| British Cricket Balls Limited | Manufacturing | 1961 |
| British Limbless Ex-Service Men's Association | Other services | 2000 |
| British Metal Tubes and Fittings Association Limited | Other services | 2022 |
| British Universities SKI Club Limited | Arts & recreation | 2017 |
| Britprecision Altimeters Ltd | Manufacturing | 2025 |
| BRM Interiors Ltd | Construction | 2026 |
| BRO and Co Traders Limited | Construction | 2021 |
| Broad EYE Ltd | Professional & scientific | 2013 |
| Broadmead Leisure Limited | Other services | 2004 |
| Broadside Properties Ltd | Real estate | 2014 |
| Broadvent Ltd | Administrative & support | 2023 |
| Brobson Enterprise Ltd | Wholesale & retail | 2025 |
| Brodie (Bansons) Limited | Construction | 2017 |
| Brodie (Chelmsford) Limited | Construction | 2021 |
| Brodie Property Group Limited | Financial services | 2017 |
| Brodie Property Investments Limited | Real estate | 2011 |
| Brodie Smith Limited | Construction | 2024 |
| Broise Limited | Administrative & support | 2017 |
| BROKER2U Limited | Financial services | 2014 |
| Brook Services Limited | Information & communication | 2022 |
| Brook View (Ongar) Management Company Limited | Real estate | 2022 |
| Brook Wise Limited | Construction | 2021 |
| Brooke Harmony Limited | Professional & scientific | 2024 |
| Brooke-Walder Fine Art Limited | Wholesale & retail | 2024 |
| Brookfield Acre Ltd | Information & communication | 2025 |
| Brookfield House (EN8) RTM Company Limited | Households | 2025 |
| Brookland Marine Limited | Manufacturing | 2012 |
| Brooklands Farm Management Limited | Agriculture & fishing | 2024 |
| Brooklands Howe Green Management Company Limited | Real estate | 2019 |
| Brooksea Limited | Financial services | 2014 |
| Brookside Crescent Management Limited | Real estate | 2015 |
| Broomfield Barbers Ltd | Other services | 2025 |
| Broomfield FC Services Ltd | Arts & recreation | 2020 |
| Broomfield Hall Limited | Agriculture & fishing | 1978 |
| Broomfield House Management Company Limited | Households | 1977 |
| Broomfield Lodge Management Limited | Households | 2009 |
| Broomfield News Limited | Information & communication | 2025 |
| Broomfield Pantry Ltd | Hospitality | 2025 |
| Broomfield Tyres Ltd | Wholesale & retail | 2020 |
| Broomfield Wheels Ltd | Wholesale & retail | 2025 |
| Brothers Administration T/As Brothers Cleaning Limited | Administrative & support | 2020 |
| Brothers Band Media Production Ltd | Arts & recreation | 2025 |
| Brothers UK Scaffolding Limited | Construction | 2017 |
| Brownes Ventures Limited | Other services | 2024 |
| Browns Maintenance Ltd | Construction | 2024 |
| Brownsted Limited | Information & communication | 2012 |
| Bruce Burlington and Company Limited | Wholesale & retail | 1946 |
| Brummells Limited | Wholesale & retail | 2005 |
| Brunker Limited | Professional & scientific | 2016 |
| Brunning Flooring Ltd | Construction | 2024 |
| Brunning Group Ltd | Construction | 2025 |
| Brunswick Quay (100-103) Management Limited | Real estate | 1985 |
| Bryanston Square Freehold Ltd | Households | 2021 |
| Bryant Properties (UK) Limited | Real estate | 2009 |
| Bryden Briflex Limited | Construction | 1973 |
| Bryden Electrical Ltd | Construction | 2014 |
| Bryden Group Ltd | Real estate | 2020 |
| Bryn Derwen Services Ltd | Professional & scientific | 2021 |
| BS Hand Car Wash Ltd | Administrative & support | 2026 |
| BS Property Management Ltd | Real estate | 2024 |
| BSB Limited | Construction | 2002 |
| BSF Trading Limited | Professional & scientific | 2014 |
| BSH Contractors Ltd | Construction | 2021 |
| Bshd Ltd | Real estate | 2018 |
| BSJ Electrical Limited | Construction | 2019 |
| BSK International Ltd | Information & communication | 2026 |
| BSL Express Spares Limited | Manufacturing | 2015 |