| Bloqwise Ltd | Information & communication | 2018 |
| Blossom Catering Services Ltd | Administrative & support | 2022 |
| Blossoms Care Home Limited | Hospitality | 2013 |
| Blue Chest Development Limited | Real estate | 2020 |
| Blue Cove Estates Ltd | Real estate | 2016 |
| Blue FOX Media Limited | Professional & scientific | 1999 |
| Blue Light Security Systems Ltd | Administrative & support | 2014 |
| Blue Monkey IT Limited | Professional & scientific | 2025 |
| Blue Orchid Estates Ltd | Real estate | 2025 |
| Blue Projects (UK) Limited | Administrative & support | 2014 |
| Bluebell Homes Ltd | Real estate | 2026 |
| Bluebird Security Systems Limited | Administrative & support | 1997 |
| BM Destination Limited | Transport & logistics | 2019 |
| BM Digital Consulting Ltd | Information & communication | 2025 |
| BMG Build Commercial Ltd | Construction | 2022 |
| BMG Build Ltd | Construction | 2020 |
| BML Heating Limited | Construction | 2023 |
| BMR Skills Limited | Administrative & support | 2021 |
| Bmrl Property Limited | Real estate | 2025 |
| BN3 Health Consultants Limited | Administrative & support | 2013 |
| Boaz Gabriel Ltd. | Administrative & support | 2020 |
| Bodhi Electrical Limited | Construction | 2024 |
| Bodyflex Training and Nutrition Limited | Health & social care | 2013 |
| Bodyworks London Limited | Health & social care | 2025 |
| Boiler Wizards Ltd | Professional & scientific | 2025 |
| Boleyn Railway Engineering Solutions Limited | Construction | 2016 |
| Bolt Building and Construction Ltd | Construction | 2021 |
| Bolt Properties Limited | Real estate | 2024 |
| Bond Street (Innovative Business Structuring) Limited | Professional & scientific | 2022 |
| Bonnies (Blackfen) Limited | Wholesale & retail | 2013 |
| Bonnies Boutique Limited | Wholesale & retail | 2018 |
| Bonnies Property Company Limited | Financial services | 2024 |
| Booth Elliott & Co. Limited | Wholesale & retail | 1962 |
| Boots Healthcare Limited | Health & social care | 2014 |
| Boroco Ventures Ltd | Real estate | 2025 |
| Boru Consulting Limited | Administrative & support | 2026 |
| Boson Motoring World Ltd | Wholesale & retail | 2020 |
| Both Sides Ltd | Arts & recreation | 2014 |
| Bourne Road Holdings Limited | Professional & scientific | 2005 |
| Bower Homes Limited | Construction | 2015 |
| Box 4 YOU Sidcup Limited | Wholesale & retail | 2021 |
| Boyles’ Sidcup Limited | Administrative & support | 2021 |
| BP Eyecare Limited | Health & social care | 2008 |
| BPM Electrical Limited | Construction | 2015 |
| Bradley Grant Music Limited | Administrative & support | 2017 |
| Braidwood Building Services Limited | Construction | 2006 |
| Braindump Ltd | Administrative & support | 2023 |
| Brandeaux Limited | Construction | 2014 |
| Branding Latin America Limited | Administrative & support | 2007 |
| Branding the World Limited | Professional & scientific | 2019 |
| Brasels Beauty Ltd | Wholesale & retail | 2025 |
| Bravr Limited | Information & communication | 2007 |
| Bread & Circus Creative Limited | Administrative & support | 2015 |
| Breezy AC Ltd | Construction | 2026 |
| Breis 2025 Limited | Professional & scientific | 2025 |
| Breis Limited | Professional & scientific | 2021 |
| Brekstar Ltd | Real estate | 2024 |
| Brensted Limited | Households | 1981 |
| Brett Clark Ltd | Administrative & support | 2010 |
| Brett-Smith Builders Limited | Construction | 2006 |
| Bretwalda Ltd | Extraterritorial | 2020 |
| Brew House Holdings Sidcup Limited | Hospitality | 2025 |
| Brew House Wine and Bistro Sidcup Limited | Hospitality | 2025 |
| Brian Phoebe Limited | Construction | 2024 |
| Bright Ideas Electrical Services Limited | Construction | 2024 |
| Brightsteps Support Ltd | Health & social care | 2025 |
| Brightsunproperty Ltd | Hospitality | 2020 |
| Brimeux Accounting Services Ltd | Professional & scientific | 2019 |
| Briselden Search Consultancy Limited | Professional & scientific | 2026 |
| Britannia Automation Limited | Administrative & support | 2017 |
| Britannia-West Limited | Construction | 2017 |
| Britcode Innovations Limited | Information & communication | 2025 |
| British Racing & Sports Car Club Limited | Arts & recreation | 1950 |
| Britton Plastering Services Limited | Construction | 2018 |
| Broad Economics Ltd | Information & communication | 2015 |
| Broadcast Engineering Ltd | Professional & scientific | 2016 |
| Broadway 208 Limited | Real estate | 2025 |
| Broadway 267 Limited | Real estate | 2018 |
| Broadway House 210-214 Limited | Real estate | 2015 |
| Bromley Corperate Enterprises Ltd | Real estate | 2013 |
| Bromley DRY Cleaners Limited | Other services | 2017 |
| Bromley Heating Limited | Administrative & support | 2004 |
| Bromley Plumbers Limited | Construction | 2017 |
| Bronson Creative Limited | Professional & scientific | 2018 |
| Bronze Cabinet Development Limited | Real estate | 2020 |
| Brothers in Floor Ltd | Administrative & support | 2022 |
| Brown Chesterfield Development Limited | Real estate | 2022 |
| Browns of Chester 1780 Limited | Wholesale & retail | 2022 |
| BRP London Ltd | Hospitality | 2015 |
| Bruce Bruce & Co Limited | Real estate | 2018 |
| Bruckmay Investments Limited | Real estate | 2021 |
| Bruin Project Consulting Limited | Information & communication | 2020 |
| Bryant Plant Limited | Financial services | 2015 |
| BS Infotech Limited | Administrative & support | 2016 |
| BST Technologies Ltd | Wholesale & retail | 2023 |
| BTH Construction Ltd | Construction | 2026 |
| Bubbles Nurseries Limited | Health & social care | 2014 |
| Buckle Richards Studio Limited | Professional & scientific | 2026 |
| Buddha Beachwear Limited | Manufacturing | 2013 |
| Buicon Limited | Administrative & support | 2011 |