| Big Redzhi Ltd | Construction | 2024 |
| Big Sales Limited | Wholesale & retail | 2015 |
| Big Talent Media Limited | Information & communication | 2012 |
| Bigfocus Limited | Real estate | 1997 |
| Bike Clinique Ltd | Wholesale & retail | 2012 |
| Bilan Store International Limited | Wholesale & retail | 2026 |
| Bilberry Manor Management Limited | Households | 1977 |
| Bill Coppard Building Services Limited | Construction | 2011 |
| Billbrooke Property Ltd | Real estate | 2016 |
| Binapani Ltd | Education | 2023 |
| Bing Research Limited | Professional & scientific | 2011 |
| Binutex Financial Consultants Limited | Professional & scientific | 2023 |
| Biomimetic Technology Limited | Professional & scientific | 2009 |
| Birdbase Ltd | Construction | 2021 |
| Birtway Court Residents Association Limited | Households | 1979 |
| Bismillahi Properties Ltd | Real estate | 2025 |
| Bisongable Limited | Professional & scientific | 2013 |
| Biswas Properties Limited | Real estate | 2024 |
| Bitac Contractors Limited | Other services | 1973 |
| Bite ME Delights Limited | Hospitality | 2026 |
| Bitspoke Ltd | Information & communication | 2011 |
| BIZ Asia Limited | Transport & logistics | 2007 |
| BJJ UP Ltd | Wholesale & retail | 2023 |
| BKB Installations Ltd | Construction | 2026 |
| BL Carpets Ltd | Construction | 2022 |
| Black Box Tattoo Ltd | Other services | 2021 |
| Black Chilli London Limited | Wholesale & retail | 2012 |
| Black Cowboy Coffee Ltd | Wholesale & retail | 2015 |
| Black Cowboy Jeans Co Ltd | Manufacturing | 2016 |
| Black Cowboy Ltd | Wholesale & retail | 2023 |
| Black Shrine Ltd | Wholesale & retail | 2025 |
| Black Swan Festivals Limited | Arts & recreation | 2018 |
| Blackhawk Guttering Services Ltd | Construction | 2015 |
| Blackhawk Roofing Services Ltd | Construction | 2015 |
| Blackmer Consulting Ltd | Education | 2021 |
| Blackpearl Global Limited | Wholesale & retail | 2021 |
| Blackridge Risk Services Ltd | Financial services | 2026 |
| Blackstone Assets Ltd | Real estate | 2020 |
| Blackwolf Marketing Ltd | Wholesale & retail | 2026 |
| Blakeney Services Limited | Professional & scientific | 2024 |
| Blakers Yard Management Company Limited | Households | 2026 |
| Blakeshore Services Ltd | Wholesale & retail | 2019 |
| Blankets and More Ltd | Manufacturing | 2019 |
| Blastnet Limited | Professional & scientific | 2002 |
| Bleak London Ltd | Wholesale & retail | 2020 |
| Blem Retail Ltd | Wholesale & retail | 2024 |
| Bless OUR Show Ltd | Arts & recreation | 2026 |
| BLF Rigging Limited | Information & communication | 2021 |
| Bligh Limited | Other services | 2017 |
| Blink Creative Studio Ltd | Information & communication | 2026 |
| Bliss Flooring Services Ltd | Construction | 2025 |
| Bliss Flooring Solutions Ltd | Construction | 2025 |
| Bliss London Properties Ltd | Real estate | 2022 |
| Blockhead Properties Limited | Real estate | 2022 |
| Blocnest Limited | Construction | 2025 |
| Blondessentials Ltd | Wholesale & retail | 2025 |
| Bloom MNG Limited | Professional & scientific | 2019 |
| Bloomsbury Intelligence and Security CIC | Professional & scientific | 2025 |
| Blossom Concept Consult (UK) Limited | Administrative & support | 2014 |
| Blue & Yellow 2 Ltd | Construction | 2025 |
| Blue Bay Bridge Ltd. | Wholesale & retail | 2023 |
| Blue FIN International Shipping Limited | Transport & logistics | 2021 |
| Blue Flames Associates Limited | Energy | 2010 |
| Blue Gecko Architecture Limited | Professional & scientific | 2015 |
| Blue Lagoon 16 Properties Limited | Real estate | 2018 |
| Blue Multiplier Limited | Financial services | 2020 |
| Blue Ocean Real Estate One Limited | Real estate | 2023 |
| Blue Ocean Residency Limited | Real estate | 2023 |
| Blue Planet Cars Ltd | Wholesale & retail | 2024 |
| Blue Rose Universal Ltd | Professional & scientific | 2015 |
| Blue Sky Lighting Ltd | Wholesale & retail | 2007 |
| Blue Star Import & Export Limited | Wholesale & retail | 2004 |
| Blue Theta Limited | Information & communication | 2021 |
| Blue Tree Waste Limited | Water & waste | 2020 |
| Bluebell Design Consultants Limited | Construction | 2012 |
| Bluebells Designer Children's Wear Ltd | Wholesale & retail | 2022 |
| Blueberries Solutions Ltd | Health & social care | 2024 |
| Bluebox Build Ltd | Construction | 2022 |
| Bluefly Engineering Limited | Manufacturing | 2019 |
| Bluefoxdm Ltd | Information & communication | 2014 |
| Blueprintco Ltd | Professional & scientific | 2023 |
| Bluer Solutions Limited | Administrative & support | 2015 |
| Blueteam Ltd | Administrative & support | 2019 |
| Bluewood Training Ltd | Education | 2006 |
| Blum & Blum Limited | Professional & scientific | 2013 |
| Blundias Limited | Information & communication | 2026 |
| Blythe Commercial Properties Ltd | Real estate | 2020 |
| Blythe Property Holdings Ltd | Real estate | 2017 |
| Blythe Property Management Ltd | Real estate | 2017 |
| Blythe Residential Properties Ltd | Real estate | 2017 |
| Blythewood Court Limited | Administrative & support | 1993 |
| BM Direct Consulting Limited | Information & communication | 2018 |
| Bmed Limited | Professional & scientific | 2012 |
| BMP Imperium Group Ltd | Transport & logistics | 2026 |
| BMS Construction (South East) Limited | Construction | 2022 |
| BNA Healthcare Limited | Administrative & support | 2010 |
| BNN Consultancy Ltd | Transport & logistics | 2020 |
| BNS Accounting Ltd | Professional & scientific | 2018 |
| Boat Harbour (London) Limited | Wholesale & retail | 1963 |
| Body Mentors Hildenborough Limited | Arts & recreation | 2021 |