| Better Business (London) Limited | Professional & scientific | 2016 |
| Better Earth Limited | Financial services | 2023 |
| Better Homes (London) Ltd | Real estate | 2020 |
| Better Rooms Limited | Real estate | 2013 |
| Better the Devil Ltd | Financial services | 2019 |
| Better Trade Frames Ltd | Construction | 2013 |
| Between the Beats Ltd | Arts & recreation | 2024 |
| Bevans Media Ltd | Information & communication | 2024 |
| Bewl Events & Waterpark Limited | Arts & recreation | 2015 |
| BEX Hamilton Green Rooms Ltd | Professional & scientific | 2026 |
| Beyond Kitchens Ltd | Construction | 2007 |
| Beyond People Ltd | Professional & scientific | 2017 |
| Beyond Repair Entertainment Ltd | Arts & recreation | 2016 |
| Beyond the Barre Limited | Education | 2026 |
| Beyond the Kitchen Table Ltd. | Information & communication | 2012 |
| BEÒ Connect Ltd | Information & communication | 2023 |
| BFC Holdings Ltd | Administrative & support | 2019 |
| BFC Property Investment & Developments Ltd | Construction | 2019 |
| BG Catering Ltd | Hospitality | 2026 |
| BHB Drainage & Plumbing Ltd | Water & waste | 2022 |
| Bhrv (Engineering) Limited | Wholesale & retail | 2002 |
| Bhrv Refrigerated Vehicles Limited | Wholesale & retail | 2016 |
| Bickley Lettings Limited | Real estate | 2014 |
| Bickley Property Owners Ltd | Real estate | 2019 |
| Bickley Surveying Services Ltd | Professional & scientific | 2019 |
| Biendesign Limited | Wholesale & retail | 2018 |
| Big G Productions Limited | Arts & recreation | 1983 |
| Big Trading Limited | Wholesale & retail | 2022 |
| Bigbadweb Limited | Information & communication | 2016 |
| Bigg-In Couriers Ltd | Transport & logistics | 2014 |
| Biggsolutions Ltd | Administrative & support | 2003 |
| Bill Hewlett Associates Ltd | Professional & scientific | 2020 |
| BIM Consult Ltd | Professional & scientific | 2014 |
| Bimco Trading LLP | | 2022 |
| Binary Impact Creative Services Limited | Professional & scientific | 2013 |
| Binfield Farm (IOW) LLP | | 2012 |
| Binigill Limited | Real estate | 2014 |
| Bion.Io Ltd | Professional & scientific | 2020 |
| Biotherm (UK) Limited | Extraterritorial | 2022 |
| Biothermal Green Energy Limited | Water & waste | 2025 |
| Biothermal Green Energy Solutions Limited | Water & waste | 2025 |
| Biothermic Green Energy Limited | Water & waste | 2025 |
| Biothermic Solutions Limited | Water & waste | 2025 |
| Birch Place Management Company Limited | Real estate | 1999 |
| Birchfields Maintenance and Construction Limited | Construction | 2014 |
| Birchwood Car Sales Ltd | Wholesale & retail | 2022 |
| Bird Girl Limited | Arts & recreation | 2003 |
| Birdynumnum Ltd | Arts & recreation | 2013 |
| Birling Vehicle Solutions Limited | Wholesale & retail | 2018 |
| Birnat Limited | Wholesale & retail | 1986 |
| Bishops Court Management Limited | Real estate | 1980 |
| Bishops Investments Limited | Real estate | 2006 |
| Bishops U.K. Limited | Real estate | 2003 |
| Bitknox Ltd | Information & communication | 2026 |
| Bizzy Lizzys Ltd | Administrative & support | 2023 |
| Bjorn Build Ltd | Construction | 2018 |
| BJR Limited | Other services | 2019 |
| BK Skips Limited | Water & waste | 2012 |
| Bkvs Property Ltd | Real estate | 2020 |
| BL Solar Energy Ltd | Energy | 2025 |
| Black & White Planning Ltd | Professional & scientific | 2026 |
| Black Blossom Alliance CIC | Education | 2025 |
| Black Blox CIC | Professional & scientific | 2026 |
| Black Sheep Technology Limited | Information & communication | 2019 |
| Blacksheep Films Limited | Arts & recreation | 1984 |
| Blackthorn Commercials Ltd | Wholesale & retail | 2012 |
| Bladez Grooming Ltd | Other services | 2025 |
| Bladon Group Limited | Construction | 2024 |
| Blake Assessors Limited | Administrative & support | 2009 |
| Blake Thomas Holdings Ltd | Real estate | 2025 |
| Blank Cheque Holdings Ltd | Financial services | 2022 |
| Blau Ltd | Wholesale & retail | 2022 |
| Blaze Autos Limited | Wholesale & retail | 2023 |
| Blaze Group Limited | Administrative & support | 2017 |
| BLC Investments Ltd | Real estate | 2023 |
| Bleu-Zig Solutions Limited | Health & social care | 2018 |
| Blewers Holdings Limited | Professional & scientific | 2008 |
| Blewers Timber Limited | Professional & scientific | 1997 |
| Blipit Limited | Extraterritorial | 2011 |
| Blitz Corporation Limited | Wholesale & retail | 1993 |
| Blockchain Property Management Limited | Real estate | 1987 |
| Blooming Liberty Ltd | Manufacturing | 2022 |
| Bloomingdale Properties (Europe) Ltd. | Professional & scientific | 1998 |
| Blu-Print Project Management Ltd | Information & communication | 2016 |
| Blue Acorns Associates Limited | Professional & scientific | 2012 |
| Blue Auto Finance Limited | Financial services | 2014 |
| Blue Box Marketing Ltd | Professional & scientific | 2012 |
| Blue Film & TV Lighting Limited | Information & communication | 2012 |
| Blue Horseshoe Enterprises Ltd | Financial services | 2022 |
| Blue Keys Estates Ltd | Real estate | 2022 |
| Blue Lamp Maintenance Ltd | Professional & scientific | 2024 |
| Blue Posts Capital Limited | Financial services | 2025 |
| Blue Sky Resourcing Limited | Administrative & support | 2012 |
| Blue Spark Limited | Information & communication | 2000 |
| Blue Tang Consulting Limited | Professional & scientific | 2025 |
| Bluebell Cemetery Property Limited | Other services | 2013 |
| Bluebell Distribution Ltd | Manufacturing | 2026 |
| Bluebell Farm Management Limited | Households | 2016 |
| Blueberry Goose Limited | Professional & scientific | 2015 |
| Bluegum Construction Limited | Construction | 2012 |