| Beauty by Amber Ltd | Other services | 2023 |
| Beauty Lounge Maidstone Ltd | Other services | 2016 |
| Beauview Landscapes Limited | Administrative & support | 2022 |
| Beaux Bagels Limited | Hospitality | 1999 |
| BEB Accountancy Limited | Professional & scientific | 2019 |
| Beccra Limited | Real estate | 2022 |
| Becko - Travel OS Ltd | Information & communication | 2026 |
| Becourt Communications Ltd | Professional & scientific | 2026 |
| Bedford Mews Management Limited | Extraterritorial | 2003 |
| Bedlars Development LLP | | 2011 |
| Bedlars Holdings (UK) LLP | | 2010 |
| Bedlars Holdings Limited | Real estate | 1964 |
| BEE Craft Limited | Information & communication | 1949 |
| Beee Happy Ltd | Other services | 2025 |
| Beer Seller Ltd | Hospitality | 2017 |
| Beever Estates Limited | Financial services | 2015 |
| Beezoo Espresso Bar Ltd | Hospitality | 2013 |
| Behoma Limited | Real estate | 2018 |
| Being ME Events Limited | Extraterritorial | 2010 |
| Beit David Capital Ltd | Professional & scientific | 2018 |
| Bella Kent Limited | Hospitality | 2025 |
| Bella Nailux Limited | Other services | 2019 |
| Bella’S Blooms Florist Ltd | Wholesale & retail | 2025 |
| Bellr Group Limited | Wholesale & retail | 2020 |
| Bemanic Marquee Hire Limited | Administrative & support | 2023 |
| Bembems Stores Ltd | Wholesale & retail | 2024 |
| BEN Trovato Partnership | | 1999 |
| Ben's Kitchen Ltd. | Manufacturing | 2021 |
| Benchmark Joinery Limited | Extraterritorial | 2013 |
| Bendrix Limited | Professional & scientific | 2018 |
| Benja's Limited | Wholesale & retail | 1999 |
| Bensons Decorative Solutions Limited | Administrative & support | 2011 |
| Benth Furniture Limited | Manufacturing | 2023 |
| Bentley Parks Group Limited | Construction | 2022 |
| Bering International Ltd | Wholesale & retail | 2020 |
| Berkshire EYE Surgery Ltd | Health & social care | 2020 |
| Berkshire Medical Estates Ltd | Health & social care | 2021 |
| Berkshire Medical LLP | | 2021 |
| Berlinetta Classic Car Concierge Ltd | Other services | 2025 |
| Bermondsey Medical Ltd | Health & social care | 2020 |
| Bernard Property Limited | Real estate | 2024 |
| Bernette Court Limited | Households | 2000 |
| Berovic Imaging Services Ltd | Health & social care | 2026 |
| Berry Place Models Limited | Professional & scientific | 1989 |
| Bertie's Wood Fuel Limited | Wholesale & retail | 2010 |
| Bespoke Concealment Systems Ltd | Wholesale & retail | 2021 |
| Better Things Ltd | Transport & logistics | 2023 |
| Beulah Investment Management Limited | Professional & scientific | 2025 |
| Bevlss Limited | Wholesale & retail | 2020 |
| Beware of the Leopard Limited | Professional & scientific | 2023 |
| Beyond TV Limited | Information & communication | 2005 |
| BG Information Systems Limited | Information & communication | 2021 |
| Bhag Consulting Services Limited | Information & communication | 2022 |
| Bham Consultancy Limited | Wholesale & retail | 2014 |
| Bhardwaj Brooks Limited | Professional & scientific | 2025 |
| Bhavana Infotech Limited | Information & communication | 2015 |
| Bholt Health Ltd | Health & social care | 2022 |
| BHP Media Ltd | Information & communication | 2020 |
| Bicycle International Limited | Professional & scientific | 2022 |
| Bicycle London Limited | Professional & scientific | 2021 |
| Bicycle Studio Limited | Professional & scientific | 2023 |
| BID Buddies Ltd | Wholesale & retail | 2025 |
| Big Cat Creative Limited | Professional & scientific | 2014 |
| Big Mouth Bakes Ltd | Wholesale & retail | 2025 |
| Big Thinkers Ltd | Education | 2020 |
| Big Train Limited | Professional & scientific | 2020 |
| Biggboss Reggie Ltd | Other services | 2021 |
| Billi Currie Limited | Other services | 2007 |
| Billsafe Ltd | Extraterritorial | 2017 |
| Bingley Industries Ltd | Professional & scientific | 2015 |
| Bintumani Consulting Limited | Other services | 2008 |
| Bioat Consulting Limited | Professional & scientific | 2025 |
| Biogs Limited | Information & communication | 2005 |
| Biotrack Technologies Limited | Financial services | 2025 |
| Birthstones Childcare Services Limited | Other services | 2002 |
| Bitlouder Limited | Information & communication | 2005 |
| Bitshifter Limited | Information & communication | 2003 |
| Bizarch Ltd | Professional & scientific | 2017 |
| Bizzy Bees Cleaning Services Ltd | Administrative & support | 2024 |
| Bizzy Maid Ltd | Other services | 2013 |
| BJA Services Limited | Agriculture & fishing | 2007 |
| Bjohn Logistics Limited | Wholesale & retail | 2012 |
| BJS Dryliners Ltd | Construction | 2020 |
| Black Cash Limited | Professional & scientific | 2019 |
| Black Cat Acoustic Environments Limited | Professional & scientific | 1998 |
| Black Cat Acoustics Limited | Extraterritorial | 2006 |
| Black Cat Music Limited | Wholesale & retail | 1991 |
| Black Horse Express Ltd | Transport & logistics | 2023 |
| Black Rock Express Insurance and Financial Services Limited | Financial services | 2000 |
| Black Square Executive Cars Limited | Transport & logistics | 2022 |
| Black T Stage Building Limited | Manufacturing | 2025 |
| Black T Stage Engineering PLC | Manufacturing | 2026 |
| Blackberry UK Construction Ltd | Construction | 2016 |
| Blackfriars Developments Limited | Construction | 1986 |
| Blackfriars Properties Limited | Professional & scientific | 1984 |
| Blackfriars Property Consultancy Limited | Professional & scientific | 2006 |
| Blackfriars Property Group Limited | Professional & scientific | 2006 |
| Blackwater Lodge Retreat LLP | | 2010 |
| Blakestanley Limited | Real estate | 2018 |
| BLD Property Ltd | Real estate | 2016 |