| Best Bazaar Ltd | Wholesale & retail | 2025 |
| Best Distribution Limited | Wholesale & retail | 2011 |
| Best Facility Management & Asset Protection Company Ltd | Wholesale & retail | 2021 |
| Best Festivals Limited | Arts & recreation | 2017 |
| Best in the West Ltd | Other services | 2023 |
| Best Move Homes Ltd | Real estate | 2023 |
| Best Move London Ltd | Real estate | 2022 |
| Best Property Deals Ltd | Real estate | 2024 |
| Best Steel Fixing Ltd | Construction | 2024 |
| Best's Pallets Ltd. | Manufacturing | 2019 |
| Bettapools Ltd | Construction | 2021 |
| Better Brow Nail Bar Ltd | Other services | 2026 |
| Beverly Brook Caffè Ltd | Hospitality | 2025 |
| Bewell IT Limited | Information & communication | 2024 |
| Bfl-Media Limited | Information & communication | 2025 |
| BH IT Ltd | Information & communication | 2014 |
| BH Sports Group Ltd | Professional & scientific | 2024 |
| Bhaagya Limited | Other services | 2024 |
| Bhakti Arts Photography Limited | Professional & scientific | 2009 |
| Bhangu Roofing Ltd | Construction | 2021 |
| Bhavani IT Seva Sanstha Ltd | Information & communication | 2012 |
| Bhooma IT Solutions Limited | Information & communication | 2024 |
| Bhosale Enterprise UK Limited | Other services | 2017 |
| Bhosale Properties Limited | Real estate | 2024 |
| BIC Infotech UK Ltd | Real estate | 2018 |
| Big Data Factory Limited | Information & communication | 2016 |
| Big Data Science & Technology Limited | Information & communication | 2018 |
| Bilal Waheed Traders Ltd | Wholesale & retail | 2025 |
| Bilginatwork Ltd | Professional & scientific | 2018 |
| Bimouska Shop Limited | Wholesale & retail | 2025 |
| BIN Ghannam Accounting & Auditing Ltd | Professional & scientific | 2024 |
| Binsols (GB) Limited | Information & communication | 2018 |
| Bioshuk Limited | Education | 2025 |
| BIR Logistics Limited | Transport & logistics | 2025 |
| Birch Finance Ltd | Professional & scientific | 2021 |
| Birtania Ltd | Wholesale & retail | 2019 |
| Bisheela Limited | Real estate | 2025 |
| Bison Consulting Services Ltd | Professional & scientific | 2023 |
| Biteful Ltd | Hospitality | 2024 |
| Bitfolk Limited | Information & communication | 2006 |
| Bitrescue Ltd | Manufacturing | 2025 |
| Bizi Bikes Ltd | Wholesale & retail | 2023 |
| Black Ancora Limited | Other services | 2018 |
| Black HAT Tiling Ltd | Construction | 2016 |
| Black Rose Build Ltd | Construction | 2024 |
| Blacklight Film & TV Limited | Information & communication | 2007 |
| Blacknight Capital Limited | Financial services | 2026 |
| Blackstone Security and Resources Ltd | Administrative & support | 2025 |
| Blacktie London Chauffeurs Ltd | Transport & logistics | 2025 |
| Blana Floor Sanding Ltd | Manufacturing | 2024 |
| Blaze Integrated Services Ltd | Health & social care | 2019 |
| Blessed Church International | Other services | 2010 |
| Blessings Homecare Services Limited | Health & social care | 2025 |
| Bleu Nile Ltd | Wholesale & retail | 2024 |
| BLINDSFITTED4U Limited | Construction | 2018 |
| Bling Crystals Ltd | Wholesale & retail | 2020 |
| Blingerati Ventures Limited | Wholesale & retail | 2019 |
| Bliss Balloons Ltd | Professional & scientific | 2025 |
| Blockom Ltd | Information & communication | 2024 |
| Bloom & Brew Cafe Limited | Wholesale & retail | 2025 |
| Blossoms in Bloom Ltd | Wholesale & retail | 2016 |
| Bluclinics London Ltd | Other services | 2025 |
| Blue ANN Financial Ltd | Information & communication | 2026 |
| Blue Arch Property Limited | Real estate | 2025 |
| Blue Bay Tech Limited | Information & communication | 2012 |
| Blue Connect Limited | Transport & logistics | 2007 |
| Blue Island Associates Ltd | Professional & scientific | 2023 |
| Blue Lotus Facilities Limited | Hospitality | 2023 |
| Blue Moon Property Ltd | Real estate | 2025 |
| Blue Nile Recruitment Limited | Administrative & support | 2024 |
| Blue Skip London Ltd | Water & waste | 2012 |
| Bluegate Estates Ltd | Real estate | 2026 |
| Bluemar Services Ltd | Professional & scientific | 2014 |
| Blueridge Trading Limited | Wholesale & retail | 2025 |
| Blutik Infotainment Ltd | Professional & scientific | 2025 |
| BMD08 Construction Ltd | Construction | 2019 |
| BMK Investment Ltd | Real estate | 2015 |
| BN Networks Ltd | Information & communication | 2015 |
| BNS Builds Ltd | Construction | 2025 |
| Bodrans Ltd | Transport & logistics | 2018 |
| Boga Style Limited | Construction | 2013 |
| Boiler Medic Plumbing & Heating Ltd | Construction | 2025 |
| Bokhara Rugs UK Ltd | Wholesale & retail | 2012 |
| Boldrin Brothers Services Ltd | Transport & logistics | 2014 |
| Bookinntravels Ltd | Transport & logistics | 2025 |
| Boomer Articles Limited | Wholesale & retail | 2023 |
| Booster Solutions Limited | Information & communication | 2024 |
| Boove Limited | Professional & scientific | 2015 |
| Boozekart Ltd | Wholesale & retail | 2026 |
| Bowe London Ltd | Professional & scientific | 2023 |
| Box FIFTY3 Ltd | Wholesale & retail | 2023 |
| Boxedtech Ltd | Wholesale & retail | 2018 |
| BP Logistic Movement Limited | Transport & logistics | 2017 |
| BP Portfolio Limited | Real estate | 2022 |
| BPA Utility Ltd | Construction | 2023 |
| Brahams 1965 Limited | Extraterritorial | 2014 |
| Brassworks Management Company Limited | Households | 2003 |
| Bravehearts Ltd | Health & social care | 2019 |
| Bread and Butter Bedfont Ltd | Hospitality | 2024 |
| Breakfast Ealing Limited | Hospitality | 2024 |