| Beebug Limited | Information & communication | 1983 |
| Beechgrove (Sandridge) Management Limited | Households | 1987 |
| Beechtree Restaurant Ltd | Hospitality | 2023 |
| Beehive Behaviour Services Ltd. | Health & social care | 2015 |
| Beehive Media Ltd | Professional & scientific | 2022 |
| Beelex Electrical Limited | Wholesale & retail | 2008 |
| Beesocialize Ltd | Information & communication | 2023 |
| Begley Group Limited | Financial services | 2018 |
| Behavioural Educational Services Ltd | Education | 2024 |
| Behind Restaurants Ltd | Hospitality | 2020 |
| Behr & SON Limited | Agriculture & fishing | 2020 |
| Belette Limited | Professional & scientific | 2023 |
| Beleza (UK) Limited | Wholesale & retail | 2025 |
| Belgrave Properties Limited | Real estate | 1999 |
| Belgravia Interiors Limited | Professional & scientific | 2018 |
| Belina Limited | Professional & scientific | 2025 |
| Belissima Aesthetics UK Louise Maria Ltd | Other services | 2022 |
| Bell Rock Financial Ltd | Professional & scientific | 2019 |
| Bell Sport and Classic Ltd | Other services | 2002 |
| Bella MIA Catering Ltd | Hospitality | 2026 |
| Bellania Ltd | Professional & scientific | 2010 |
| Bellanti Finance Limited | Professional & scientific | 2025 |
| Bellavia Training & Consultancy Ltd | Education | 2020 |
| Belle Investments Ltd | Financial services | 2012 |
| Belle VUE Homes Limited | Construction | 2025 |
| Bello Small Animal Ltd | Professional & scientific | 2023 |
| Bellstone Properties Limited | Real estate | 2025 |
| Belly Slide Consulting Limited | Professional & scientific | 2023 |
| Belosco Ltd | Extraterritorial | 2020 |
| Belstra Ltd | Real estate | 2025 |
| Benbarbering Ltd | Other services | 2023 |
| Bene Films Inc Limited | Information & communication | 2023 |
| Bengal Arch Limited | Hospitality | 2025 |
| Benimdosyam Ltd | Professional & scientific | 2021 |
| Benjamin Noble Consulting Ltd | Information & communication | 2023 |
| Benjamin Potts Limited | Information & communication | 2025 |
| Benmark Foundations,Limited | Wholesale & retail | 1936 |
| Benridge London Ltd | Information & communication | 2010 |
| Bens Cars London Limited | Wholesale & retail | 2025 |
| Berdice Limited | Real estate | 2020 |
| Berkeley Associates Consulting Limited | Professional & scientific | 2015 |
| Berry Business Strategy Limited | Professional & scientific | 2011 |
| Besford DCL Ltd | Real estate | 2016 |
| Bespoke Built Environment Limited | Real estate | 2024 |
| Bespoke Flooring Commercial Limited | Construction | 2023 |
| Bespoke Homes Limited | Construction | 1937 |
| Bespoke Renovation Services Ltd | Construction | 2023 |
| Best Cleaning London Ltd | Administrative & support | 2022 |
| Best Door Stripping Services Ltd | Other services | 2020 |
| Best Practice Property Limited | Professional & scientific | 2015 |
| Best Way TJ Ltd | Transport & logistics | 2022 |
| Best-One Shipping Limited | Transport & logistics | 2009 |
| Besthandymanlondon Ltd | Construction | 2016 |
| Bestwick Property Holdings Ltd | Real estate | 2024 |
| Better Behind Bars Limited | Wholesale & retail | 2013 |
| Bettersoft Limited | Information & communication | 1999 |
| Bettespol Meadows Management Company Limited | Households | 2001 |
| Beushaw Consulting Limited | Professional & scientific | 2025 |
| Bewowhealthcare Limited | Wholesale & retail | 2024 |
| Beyond Thrive Ltd | Professional & scientific | 2025 |
| BFI Property Management Limited | Real estate | 2017 |
| BGC Consulting Services Ltd | Administrative & support | 2024 |
| Bhakti Trading Ltd | Wholesale & retail | 2020 |
| Bharat Founders LP | | 2023 |
| BHB Property Limited | Real estate | 2013 |
| Bhcg Ltd | Real estate | 1999 |
| BHM Financial Services Ltd | Financial services | 2020 |
| BHS (Franchise) Ltd | Real estate | 2025 |
| Bidpartners Limited | Professional & scientific | 2003 |
| Bifrost Properties Limited | Real estate | 2014 |
| Big Advisory Ltd | Professional & scientific | 2018 |
| Big Bang Capital UK Ltd | Financial services | 2019 |
| Big Belly Events Catering Ltd | Hospitality | 2024 |
| Big Big Love Ltd | Arts & recreation | 2023 |
| Big Burden Ltd | Professional & scientific | 2020 |
| Big Dill Catering Limited | Wholesale & retail | 2024 |
| Big Face TV Limited | Extraterritorial | 2015 |
| Big Head Content Limited | Information & communication | 2019 |
| Big Juicy Burgers STA Limited | Hospitality | 2025 |
| Big Moon Publishing Limited | Professional & scientific | 2018 |
| Big PIG Ventures Ltd | Hospitality | 2023 |
| Bigger Difference Limited | Professional & scientific | 2012 |
| Biggs Winter Limited | Construction | 2018 |
| Biglimo International Ltd | Professional & scientific | 2009 |
| Billy Fearless Ltd | Information & communication | 2025 |
| BIO Engineering Ltd | Professional & scientific | 2024 |
| Bioboost Ltd | Wholesale & retail | 2023 |
| Biodal Limited | Professional & scientific | 2024 |
| Biomaterial Pioneer Ltd | Manufacturing | 2023 |
| Bionic Communications Limited | Administrative & support | 2002 |
| Birch Psychological Associates Ltd | Health & social care | 2024 |
| Birchwood Strategies LLP | | 2016 |
| Bird & Co Finance Solutions Ltd | Professional & scientific | 2024 |
| Birdseye Design Ltd | Professional & scientific | 2024 |
| Birdview Ltd | Real estate | 2015 |
| Birsen UK Ltd | Construction | 2016 |
| Bishopside Property Limited | Real estate | 2022 |
| Bitmortar Limited | Information & communication | 2025 |
| Bizzcuit Solutions Ltd | Information & communication | 2023 |
| Bizzy Blue Design Limited | Professional & scientific | 2006 |