| Bridging the GAP (BTG) Enterprise Ltd | Hospitality | 2024 |
| Bright Little Stars Enfield Limited | Education | 2025 |
| Bright Minds Finan Ltd | Wholesale & retail | 2025 |
| Bright Shift Limited | Professional & scientific | 2017 |
| Bright Spark Rewards Ltd | Education | 2025 |
| Bright Sports Consulting Limited | Arts & recreation | 2013 |
| Bright Steps Day Nursery Ltd | Education | 2025 |
| Brightcrew (Management) Limited | Real estate | 2014 |
| Brightdirection Limited | Administrative & support | 2020 |
| Brighter Bricks Construction Limited | Construction | 2025 |
| Brighter Bricks Holdings Limited | Financial services | 2024 |
| Brightness Future Investment Ltd | Real estate | 2020 |
| Brighton Marina Premier Lettings Limited | Real estate | 2016 |
| Brightonstone Ltd | Real estate | 2025 |
| Brightplace Limited | Real estate | 2016 |
| Bring the Thunder Limited | Arts & recreation | 2011 |
| Britannia Marine Services Limited | Manufacturing | 1995 |
| Britannic Property Developments Limited | Construction | 1986 |
| Britannic Trustees Limited | Construction | 1978 |
| British Academy of Jewellery Limited | Education | 2006 |
| British Hindu Sewa Samiti Ltd | Other services | 2025 |
| Brixton Bond Limited | Construction | 2019 |
| Broadash Limited | Health & social care | 2021 |
| Broadboards Limited | Professional & scientific | 2008 |
| Broadley Investment Holdings Limited | Financial services | 2025 |
| Broadley Investments Limited | Arts & recreation | 1992 |
| Broadley Music (International) Limited | Arts & recreation | 1994 |
| Broadley Records Limited | Arts & recreation | 1990 |
| Broadley Studios Limited | Information & communication | 1994 |
| Broast UK Limited | Hospitality | 2025 |
| Bromley-Morgans Limited | Other services | 2021 |
| Brompton Holidays Limited | Extraterritorial | 2015 |
| Brompton Property Ltd | Real estate | 2025 |
| Brontone Limited | Professional & scientific | 2001 |
| Bronze Linings Estates Ltd | Real estate | 2026 |
| Brook Court Management Company Limited | Households | 1983 |
| Brook Lodge Freehold Limited | Real estate | 2005 |
| Brookcray Limited | Health & social care | 2021 |
| Brooklands Jewellers Limited | Wholesale & retail | 2011 |
| Brookshill Gate RTM Company Limited | Households | 2012 |
| Brookwell Springs Healthcare Ltd | Health & social care | 2017 |
| Broomfield House Freehold Limited | Households | 2008 |
| Brosmy Management Ltd | Extraterritorial | 2012 |
| Brosnan Developments Limited | Other services | 2019 |
| Brothers Press Limited | Financial services | 2016 |
| Brown Leaf Media Ltd | Information & communication | 2021 |
| Browns Landscape Group Ltd | Administrative & support | 2018 |
| Browns Limited | Other services | 2000 |
| Brozel Films Ltd | Arts & recreation | 2015 |
| Bruma Drylining a to Z Ltd | Construction | 2019 |
| Brumalex Ltd | Construction | 2022 |
| Bruno K9 Security Limited | Administrative & support | 2026 |
| Bryn Pritchard Ltd | Construction | 2015 |
| Brynora Limited | Wholesale & retail | 2025 |
| Bryony Limited | Professional & scientific | 2001 |
| BSB Partnerships Limited | Professional & scientific | 2016 |
| BSC Construction Group Ltd | Construction | 2013 |
| BSC Facades Limited | Construction | 2025 |
| BSC Group Investments Limited | Real estate | 2025 |
| BSC Holdings Group Limited | Financial services | 2025 |
| BSC Homes Group Ltd | Construction | 2023 |
| BSC Investments Group Ltd | Real estate | 2024 |
| BSG75 Ltd | Real estate | 2014 |
| BSH Properties Limited | Real estate | 2019 |
| BSO Motor Assets Ltd | Wholesale & retail | 2026 |
| Bsocialuk Ltd | Professional & scientific | 2013 |
| BST England Ltd | Real estate | 2018 |
| BST Hallam Limited | Financial services | 2024 |
| BTL Property Design and Build Ltd | Construction | 2017 |
| BTL Property Holdings Limited | Construction | 2018 |
| BTL Property New Build Limited | Construction | 2018 |
| BTS Consult Ltd | Professional & scientific | 2019 |
| Buckingham Magnetics Ltd | Manufacturing | 2020 |
| Buckland Recruitment Ltd | Administrative & support | 2014 |
| Buckminster Properties (London) Limited | Real estate | 2018 |
| Bucks Hill Properties Ltd | Real estate | 2023 |
| Bucks Hill Stables Ltd | Agriculture & fishing | 2023 |
| BUD Enterprises Limited | Wholesale & retail | 2014 |
| Budget Removals London Ltd | Transport & logistics | 2019 |
| Budget Skips and Recycling Limited | Water & waste | 2017 |
| Budget Transport London Ltd | Transport & logistics | 2020 |
| Bugle Communications 2012 Limited | Professional & scientific | 2012 |
| Build Abode Ltd | Construction | 2016 |
| Build Smart 4 Life Ltd | Construction | 2023 |
| Build Square Ltd | Construction | 2013 |
| Buildersbox Ltd | Construction | 2019 |
| Building Services From A-Z Ltd | Construction | 2010 |
| Bujupi Properties Ltd | Real estate | 2025 |
| Bulldog Card Traders Ltd | Wholesale & retail | 2021 |
| Bullhead Construction Ltd | Construction | 2026 |
| Bulstrode Ltd | Administrative & support | 2026 |
| Bureau Bilgin Limited | Professional & scientific | 2018 |
| Bureaux Ltd | Information & communication | 2020 |
| Burger and Waffle Ltd | Hospitality | 2019 |
| Burgess Consulting Services | Professional & scientific | 2019 |
| Burghley London Limited | Wholesale & retail | 2019 |
| Buried Treasure Productions Ltd | Information & communication | 2020 |
| Burlington House Management Company (RTM) Limited | Professional & scientific | 2004 |
| Burlington Park Residents Limited | Households | 1984 |
| Burn Beauty Limited | Wholesale & retail | 2018 |