| Bismillah Pharma Ltd | Health & social care | 2023 |
| Bismillah Properties (NE) Ltd | Real estate | 2025 |
| Bismillah Property Management Limited | Real estate | 2022 |
| Bison Scaffolding Ltd | Construction | 2025 |
| Biss 53 Limited | Real estate | 2014 |
| Biss Underwriting Limited | Financial services | 2010 |
| Bissett Kenning Limited | Real estate | 1993 |
| Bite (Forest Hall) Ltd | Hospitality | 2022 |
| Bitsy BEE Gifts Ltd | Wholesale & retail | 2019 |
| Bitsync Limited | Information & communication | 2010 |
| Bittrbyte Ltd | Professional & scientific | 2025 |
| Bivilak Trade and Consults Ltd | Wholesale & retail | 2024 |
| Biya's Fashion World Ltd | Wholesale & retail | 2023 |
| Bizcentre Ltd | Administrative & support | 2017 |
| Bizzbility Ltd | Real estate | 2024 |
| BJF Joinery Limited | Construction | 2011 |
| BJR Fabs Ltd | Construction | 2016 |
| BJR Solutions North East Ltd | Construction | 2024 |
| BJW Developments Ltd | Construction | 2023 |
| Bjzx Servicio Ltd | Professional & scientific | 2025 |
| BK Associates Ltd | Professional & scientific | 2026 |
| BK Building and Maintenance Services Limited | Administrative & support | 2015 |
| BKB Consulting Limited | Professional & scientific | 2024 |
| BKC Solutions Ltd | Construction | 2025 |
| Bkeep Limited | Real estate | 2025 |
| Bkjoinery and Building Services Limited | Construction | 2021 |
| Bkmi Ltd | Financial services | 2023 |
| BL 1215 Limited | Construction | 2017 |
| BL Insulate Ltd | Construction | 2023 |
| BLA Property and Maintenance Limited | Households | 2024 |
| Black and White Engineering Holdings Ltd | Professional & scientific | 2022 |
| Black and White Engineering International Ltd | Professional & scientific | 2022 |
| Black and White Engineering Limited | Professional & scientific | 2014 |
| Black Beacon (SA) Limited | Manufacturing | 2025 |
| Black Belt Branding Ltd | Professional & scientific | 2026 |
| Black Bird Beauty Limited | Wholesale & retail | 2025 |
| Black Bull (Newcastle) Limited | Hospitality | 2017 |
| Black Isle Management Ltd. | Construction | 2012 |
| Black Packaging Ltd | Administrative & support | 2026 |
| Black RAT Logistics Ltd | Transport & logistics | 2025 |
| Black Seventeen Consulting Ltd | Professional & scientific | 2025 |
| Black Trade Construction Ltd | Professional & scientific | 2019 |
| Black Tusk Investments Limited | Financial services | 2022 |
| Black Water Design Limited | Real estate | 2024 |
| Blackbiro Services Ltd | Information & communication | 2025 |
| Blackbox Software Solutions Limited | Information & communication | 2000 |
| Blackcap Management LLP | | 2025 |
| Blackett (Newcastle) Limited | Wholesale & retail | 1945 |
| Blackfin Services Limited | Professional & scientific | 2022 |
| Blackfriars (Stowell Street) Management Company Limited | Real estate | 1998 |
| Blackfriars Cafe Bar Limited | Hospitality | 2001 |
| Blackhall Mill Community Association | Arts & recreation | 2004 |
| Blackjack Tanning Limited | Other services | 2024 |
| Blackmore Logistics Ltd | Transport & logistics | 2025 |
| Blackoak Computing Limited | Wholesale & retail | 2009 |
| Blackout Performance Coaching Ltd | Arts & recreation | 2025 |
| Blackrock Imaging Ltd | Health & social care | 2022 |
| Blacks Apps Ltd | Information & communication | 2021 |
| Blacksea OFF Licence Ltd | Wholesale & retail | 2010 |
| Blacksmith Engineering Limited | Information & communication | 2013 |
| Blacksmiths Coffee Shop Limited | Hospitality | 2003 |
| Blackstone Security Solutions Limited | Administrative & support | 2009 |
| Blackswine Farm Management Limited | Households | 2005 |
| Blackthorne Projects Limited | Extraterritorial | 2012 |
| Blacktree Technical Services Limited | Professional & scientific | 2024 |
| Blagdon Appliances Ltd | Wholesale & retail | 2013 |
| Blagdon Farming Limited | Agriculture & fishing | 1997 |
| Blagdon Nominees 1 Limited | Professional & scientific | 2014 |
| Blagdon Nominees 2 Limited | Professional & scientific | 2014 |
| Blain Property Ltd | Real estate | 2023 |
| Blair and West Limited | Administrative & support | 2018 |
| Blair Tech Ltd | Information & communication | 2026 |
| Blair West Topco Limited | Extraterritorial | 2026 |
| Blak Hats Ltd | Information & communication | 2022 |
| Blakeysparcels Ltd | Transport & logistics | 2026 |
| Bland & Wood Accounting Services Limited | Professional & scientific | 2002 |
| Bland & Wood Services Limited | Professional & scientific | 1984 |
| Blandford Brewery Estate Management Company Limited | Households | 2022 |
| Blandford Square Limited | Real estate | 2022 |
| Blane Properties (NE) Limited | Hospitality | 2018 |
| Blank Studios LLP | | 2008 |
| Blast Music Publishing Limited | Information & communication | 2011 |
| Blast Recording Limited | Information & communication | 2009 |
| Blaydon Grapplers Ltd | Education | 2025 |
| Blaydon Part Exchange Centre Ltd | Wholesale & retail | 2019 |
| Blaydon RFC Ltd | Arts & recreation | 2008 |
| Blaydon RFC Youth CIC | Education | 2022 |
| Blaydon Rugby Football Club Ltd | Arts & recreation | 2017 |
| Blaydon Tennis Club Limited | Arts & recreation | 1997 |
| Blaydon Trade Windows and Doors Limited | Arts & recreation | 1996 |
| Blazeblue Limited | Professional & scientific | 2000 |
| Blco Fenham Ltd | Other services | 2019 |
| Bleach Green Residents Management Company Limited | Real estate | 2019 |
| Blend Creative Ltd | Professional & scientific | 2024 |
| Blend Spark Ltd | Hospitality | 2025 |
| Blended! Events Limited | Arts & recreation | 2012 |
| Blenkley Property Group Limited | Real estate | 2026 |
| Bletchley Networks Limited | Information & communication | 2019 |
| BLG Delivery Ltd Limited | Transport & logistics | 2025 |
| BLG Motor Solutions Ltd | Wholesale & retail | 2023 |