| Berresinghe Limited | Construction | 2018 |
| Berry END Productions Limited | Information & communication | 2013 |
| Berry Fish Ltd. | Information & communication | 2013 |
| Bershini Holdings Ltd | Financial services | 2025 |
| Berwick Developments Limited | Construction | 1996 |
| Besherdas Limited | Professional & scientific | 2012 |
| Besherdas Properties Ltd | Real estate | 2021 |
| Besli Holdings Ltd | Real estate | 2017 |
| Bespoke Furniture Manufacturing Services Ltd | Manufacturing | 2014 |
| Bespoke Property Bureau Ltd | Real estate | 2011 |
| Bespoke Sashes Limited | Construction | 2013 |
| Bespoke.Uniforms.Company Ltd | Manufacturing | 2025 |
| Besports Consultancy Ltd | Education | 2021 |
| Best Flowers Ltd | Wholesale & retail | 2009 |
| Best Petroliums Solutions UK Limited | Administrative & support | 2007 |
| Besteld Ltd. | Wholesale & retail | 2018 |
| Bestlock Limited | Hospitality | 1990 |
| Bestsafe (UK) Limited | Information & communication | 2022 |
| Bestsafe Development (Dartford) Ltd | Construction | 2014 |
| BET Bailey Ltd | Administrative & support | 2025 |
| Beta Carlton Limited | Real estate | 2022 |
| Beth Hornsey Limited | Other services | 2002 |
| Bethersden Limited | Professional & scientific | 1987 |
| Bets Spray Renders Ltd | Construction | 2010 |
| Better Funding C.I.C. | Professional & scientific | 2025 |
| Better Life Ltd | Health & social care | 2026 |
| Better Than Real Ltd | Professional & scientific | 2016 |
| Betty Mccaul Bridal Limited | Wholesale & retail | 2015 |
| Betweenerz Ltd | Administrative & support | 2020 |
| Beverley Court Property Management Ltd | Households | 1993 |
| Bevington Care Services Limited | Health & social care | 2007 |
| Beyond Building Projects Ltd | Construction | 2024 |
| Beyond Move Ltd | Other services | 2019 |
| Beyond Projects Group Limited | Administrative & support | 2025 |
| Beyond Your World Limited | Information & communication | 2018 |
| BF Argon Limited | Real estate | 2026 |
| BF Heights Limited | Real estate | 2026 |
| BG Ants Ltd | Construction | 2017 |
| BG Apartments Ltd | Extraterritorial | 2007 |
| Bhagavathi Limited | Administrative & support | 2011 |
| Bhahi Ltd | Real estate | 2018 |
| Bhatia Ltd | Administrative & support | 2014 |
| Bhest Limited | Health & social care | 2025 |
| Bhudia Property Limited | Real estate | 2022 |
| BI Contracting Ltd | Construction | 2026 |
| Biaka Sports Management Limited | Professional & scientific | 2020 |
| Bianna Recycling (UK) Limited | Manufacturing | 2013 |
| Bibishkov IT ENG Limited | Construction | 2017 |
| Biblical Foods Limited | Manufacturing | 2013 |
| Bibsworth Ltd | Professional & scientific | 2017 |
| Bice & Birch Limited | Professional & scientific | 2025 |
| Bici Car Ltd | Wholesale & retail | 2024 |
| Biddenfield Holdings Ltd | Construction | 2021 |
| Bidwalla (Fruit & Vegetables) Limited | Wholesale & retail | 1976 |
| Big Bang Digital Limited | Professional & scientific | 2017 |
| Big Dog Investments Limited | Financial services | 2015 |
| Big Juicy Burgers (Aylesbury) Ltd | Hospitality | 2024 |
| Big Juicy Burgers (Chesham) Ltd | Hospitality | 2024 |
| Big Retail Limited | Administrative & support | 2023 |
| Big Smash Publishing Limited | Information & communication | 2014 |
| Big Yellow Sun Limited | Information & communication | 2012 |
| Bigg-Wither Limited | Extraterritorial | 2013 |
| Bija-Druma Ltd | Information & communication | 2024 |
| Bikram Limited | Arts & recreation | 2012 |
| Bills Gates (UK) Limited | Construction | 2011 |
| Bilston Shopping Centre Limited | Real estate | 2022 |
| BIM Angels Ltd | Information & communication | 2014 |
| Bincap Investments Unltd | Financial services | 2016 |
| Bindi's Swindon Ltd | Hospitality | 2019 |
| Binksy Ltd | Administrative & support | 2011 |
| Bipra Limited | Wholesale & retail | 2007 |
| Biranu Consulting Limited | Information & communication | 2017 |
| Bird Automotive Ltd | Wholesale & retail | 2018 |
| Bird Construction & Maintenance Services Ltd | Construction | 2019 |
| Bird Estate Ltd | Real estate | 2017 |
| Birmingham Capital Limited | Professional & scientific | 2025 |
| BIS Recruit Limited | Administrative & support | 2003 |
| Biscuit Boutique Limited | Manufacturing | 2019 |
| Bishops Cleaning Services Limited | Administrative & support | 2016 |
| Bishopsfield Properties Limited | Construction | 1983 |
| Biwell Power Ltd | Other services | 2014 |
| Bizzcandy Ltd | Wholesale & retail | 2020 |
| BJC Projects Ltd | Manufacturing | 2024 |
| BK Alloy Wheels Limited | Other services | 2014 |
| BKJ Properties ( London ) Ltd | Real estate | 2021 |
| BL Surfacing Contracts Ltd | Construction | 2012 |
| BL7CKSEVEN Limited | Administrative & support | 2016 |
| Black Apricot Limited | Professional & scientific | 2010 |
| Black Apricot Properties Limited | Real estate | 2020 |
| Black Brick Investments Ltd | Real estate | 2024 |
| Black Dog Design and Production Limited | Manufacturing | 2005 |
| Black Dog Digital Limited | Manufacturing | 2006 |
| Black Dolphin Military Group Limited | Administrative & support | 2018 |
| Black Dolphin Military Kennels Limited | Administrative & support | 2017 |
| Black Fashion Ltd | Professional & scientific | 2019 |
| Black Jersey Media Limited | Administrative & support | 2013 |
| Black Owned London Ltd | Manufacturing | 2020 |
| Black Pelican Limited | Administrative & support | 2025 |
| Black Square (Herts) Limited | Construction | 2019 |
| Blackbook Records Limited | Real estate | 2021 |