| Bakers of Danbury Heritage Limited | Construction | 2019 |
| Bakers of Danbury Limited | Financial services | 2019 |
| Bakers Properties Limited | Real estate | 1971 |
| BAL Barbers Ltd | Other services | 2024 |
| Bala IT Services Ltd | Information & communication | 2025 |
| Balam IT Limited | Information & communication | 2011 |
| Balancing London Limited | Professional & scientific | 2025 |
| Balch Estate Agents (Chelmsford) Ltd | Real estate | 2008 |
| Balch Estate Agents Limited | Real estate | 1990 |
| Balch Holdings Ltd | Financial services | 2008 |
| Balch Lettings Ltd | Real estate | 2008 |
| Bald Projects Limited | Administrative & support | 2018 |
| Baldock Brothers Limited | Administrative & support | 2017 |
| Baldock Property Holdings Limited | Real estate | 2022 |
| Balfour Wong Limited | Professional & scientific | 2015 |
| Balfour Motor Company Limited | Real estate | 1977 |
| Balfour Road Surgery Ltd | Health & social care | 2018 |
| Balloons of London Limited | Wholesale & retail | 1998 |
| Balson UK Limited | Construction | 2014 |
| Baltic Select Ltd | Wholesale & retail | 2026 |
| Baltihub Ltd | Hospitality | 2023 |
| BAM BAM Boogies CIC | Arts & recreation | 2017 |
| Bamad Ltd | Professional & scientific | 2014 |
| Bambeco Life Ltd | Wholesale & retail | 2022 |
| Bamboo Retreat Ltd | Health & social care | 2024 |
| Bamidel Ltd | Information & communication | 2025 |
| Banana Farm Limited | Financial services | 2025 |
| Bandino Medical Ltd | Health & social care | 2024 |
| Bandshore Limited | Real estate | 2000 |
| Bangla Academy UK | Information & communication | 2023 |
| Bannekr Ltd | Information & communication | 2025 |
| Bannister Branding Ltd | Manufacturing | 2023 |
| Bantac Services Limited | Real estate | 2017 |
| Bantock RTM Company Ltd | Households | 2021 |
| Banu Properties Ltd | Real estate | 2026 |
| Bar 7 Limited | Hospitality | 2020 |
| Bar Brothers Fitness Ltd | Arts & recreation | 2023 |
| Baracouda Solutions Ltd | Professional & scientific | 2023 |
| Barakah Group Ltd | Wholesale & retail | 2024 |
| Barber City Ltd | Other services | 2025 |
| Barber Company Holdings Limited | Real estate | 2017 |
| Barber Jackson Limited | Other services | 2000 |
| Barbertime Ltd | Other services | 2023 |
| Barbour Farms Limited | Agriculture & fishing | 2014 |
| Barclay & Page Holdings Limited | Professional & scientific | 2025 |
| Barden New Build Inspections Ltd | Construction | 2025 |
| Barduva UK Ltd | Wholesale & retail | 2015 |
| Bardwell Homes Ltd | Extraterritorial | 2016 |
| Bare Cove Technology (UK) Limited | Information & communication | 2024 |
| Bare Hospitality Ltd | Hospitality | 2025 |
| Bare Seamless Design Ltd | Construction | 2023 |
| Barefoot Healing Limited | Extraterritorial | 2021 |
| Barfords Flooring Limited | Construction | 2004 |
| Barham Court (Cuffley) Management Company Limited | Households | 2016 |
| Bari & Associates Limited | Real estate | 2018 |
| Barker (Essex) Limited | Manufacturing | 2018 |
| Barker Nelsam Limited | Construction | 2018 |
| Barking Brawn Limited | Financial services | 2021 |
| Barleylands Arena Ltd | Real estate | 2017 |
| Barleylands Equestrian Centre Limited | Arts & recreation | 2017 |
| Barleylands Riding School Limited | Arts & recreation | 2016 |
| Barmby Seven Limited | Real estate | 2023 |
| Barndoor Media Limited | Wholesale & retail | 2010 |
| Barnehurst Property & Maintenance Limited | Administrative & support | 2012 |
| Barnes Wedge Limited | Professional & scientific | 2013 |
| Barnoaks Management Limited | Real estate | 1963 |
| Barny Parker Building Services Ltd | Construction | 2010 |
| Barometer Holdings Limited | Real estate | 2017 |
| Baron Logistics Limited | Transport & logistics | 2017 |
| Barramundi Media Ltd | Professional & scientific | 2024 |
| Barras Capital Management PLC | Financial services | 2021 |
| Barrett Property Management Ltd | Real estate | 2024 |
| Barricard Limited | Administrative & support | 2017 |
| Barring Lake Limited | Professional & scientific | 2013 |
| Barrow Farm Riding for the Disabled Limited | Arts & recreation | 2010 |
| Barry C. Wright & Sons Limited | Construction | 2004 |
| Barry Stewart & Partners Limited | Real estate | 1998 |
| Bart's Wheels Ltd | Manufacturing | 2014 |
| Barth Italiana Ltd. | Professional & scientific | 1991 |
| Barton Court Management Company Limited | Households | 1989 |
| Bartone Ltd | Administrative & support | 2011 |
| Bartrams Close Management Limited | Households | 2020 |
| Basedefi Limited | Professional & scientific | 2020 |
| Baseline Investments Limited | Information & communication | 2002 |
| Baseline Real Estate Limited | Financial services | 2016 |
| Bash Govender Ltd | Professional & scientific | 2021 |
| Bashful Baboon Limited | Real estate | 2017 |
| Bassfords Ltd | Professional & scientific | 2019 |
| Bassment JAM Ltd | Hospitality | 2013 |
| Batchelor & Walker Care Consultancy Limited | Professional & scientific | 2026 |
| Bates Finance (Southend) Limited | Real estate | 2001 |
| Bates Finance Limited | Financial services | 1998 |
| Battelle UK Limited | Professional & scientific | 2001 |
| Battersea Estates + Trading Limited | Real estate | 2001 |
| Battlebox Holdings Ltd | Arts & recreation | 2025 |
| Battlesbridge Bootcamp Ltd | Arts & recreation | 2025 |
| Battrick Limited | Information & communication | 2005 |
| Bay Days Festival CIC | Arts & recreation | 2025 |
| Bayern Consultants Ltd | Extraterritorial | 2004 |
| Bayeswood Properties Limited | Construction | 2009 |