| Bkjj Limited | Administrative & support | 2025 |
| BL Constructive Design Ltd | Construction | 2025 |
| BLA Engineering Ltd | Professional & scientific | 2023 |
| Black Betty Logistics Ltd | Transport & logistics | 2025 |
| Black Diamond Housing Ltd | Real estate | 2026 |
| Black Heart Studios Ltd | Arts & recreation | 2026 |
| Black Horse Pubco Limited | Hospitality | 2013 |
| Black Horse Residents Management Company Limited | Households | 2007 |
| Black Properties (North East) Limited | Real estate | 2014 |
| Black Rhino Limited | Real estate | 2023 |
| Black Rose Property Management Ltd | Construction | 2024 |
| Black Writing Publishers Ltd | Information & communication | 2024 |
| Blackburn Properties NE Ltd | Real estate | 2022 |
| Blackdiamonds Concept Ltd | Construction | 2024 |
| Blackfern Consultants Ltd | Professional & scientific | 2026 |
| Blackfoot Communications Limited | Information & communication | 2013 |
| Blackheath Property Limited | Real estate | 2024 |
| Blackie 1960 Limited | Extraterritorial | 2014 |
| Blackmore Investment Ltd | Real estate | 2020 |
| Blackstart Technologies Ltd | Information & communication | 2024 |
| Blackstone Autos Ltd | Wholesale & retail | 2025 |
| Blackstone Monitoring Services Ltd | Administrative & support | 2026 |
| Blackstone NE Ltd | Real estate | 2016 |
| Blackstone Property Holdings Ltd | Real estate | 2025 |
| Blackstone Residential Lettings Ltd | Real estate | 2025 |
| Blacktek Services Limited | Professional & scientific | 2012 |
| Blackwell Water Consultancy Ltd | Professional & scientific | 2009 |
| Blade Shield Coatings Limited | Construction | 2026 |
| Blandford Refinishers Limited | Wholesale & retail | 2008 |
| Blast Furnace Projects Ltd | Education | 2022 |
| Blast Programme Limited | Education | 2014 |
| Blaze Codez Limited | Information & communication | 2026 |
| Bleating Marvellous Ltd | Transport & logistics | 2025 |
| Bled Textiles Ltd | Wholesale & retail | 2024 |
| Blenheim Investments (Cleveland) Limited | Real estate | 1979 |
| Blift Limited | Construction | 2025 |
| Blindcraft Limited | Manufacturing | 2003 |
| Blink Beauty Academy Ltd | Other services | 2023 |
| Blink EYE Wear Ltd | Health & social care | 2010 |
| Blissfully Broke Ltd | Wholesale & retail | 2025 |
| Blossom Safety Services Limited | Construction | 2013 |
| Bloughran Limited | Wholesale & retail | 2025 |
| BLS Cleaning Limited | Administrative & support | 2025 |
| Blue Gate Couriers Ltd | Transport & logistics | 2026 |
| Blue Giraffe Bicycles Ltd | Wholesale & retail | 2011 |
| Blue Icecream Ltd | Wholesale & retail | 2017 |
| Blue Leopard Prestige Ltd | Construction | 2020 |
| Blue Leopard Properties Ltd | Real estate | 2020 |
| Blue Skies Property Services Ltd | Real estate | 2016 |
| Blue Steel Properties Limited | Real estate | 2017 |
| Blue Streak Car WAS Ltd | Administrative & support | 2023 |
| Bluebird Travel (NE) Ltd | Transport & logistics | 2019 |
| Bluebox Containers Ltd | Wholesale & retail | 2026 |
| Bluebox Finishing Ltd | Construction | 2013 |
| Bluebox Removals Ltd | Transport & logistics | 2022 |
| Bluebox Sales & Hire Ltd | Wholesale & retail | 2026 |
| Bluebox Storage (North East) Ltd | Transport & logistics | 2015 |
| Bluebox Storage (Stockton) Limited | Transport & logistics | 2016 |
| Bluebrick 2020 (Construction) Ltd | Construction | 2019 |
| Bluefyn Property Management Ltd | Real estate | 2024 |
| Blueline Mechanical Ltd | Construction | 2025 |
| Bluenix Ltd | Information & communication | 2026 |
| Bluewave Stays Limited | Hospitality | 2025 |
| Blush & Glow Aesthetics Ltd | Other services | 2025 |
| Blush Hair Limited | Other services | 2007 |
| Bluvibe Ltd | Wholesale & retail | 2025 |
| BM Design North Ltd | Professional & scientific | 2024 |
| BM High Access Limited | Construction | 2025 |
| BM R&R Ltd | Construction | 2024 |
| BM891 Electrics Ltd | Construction | 2026 |
| BMC Inspection Limited | Professional & scientific | 2025 |
| BMC Insulation Limited | Construction | 2024 |
| BMC Technical Limited | Professional & scientific | 2017 |
| Bmcd Ltd | Other services | 2017 |
| BMD Projects North East Limited | Professional & scientific | 2020 |
| BME Network Community Interest Company | Other services | 2008 |
| BMM Marshall Holdings Limited | Financial services | 2021 |
| BMR Total Solutions Ltd | Professional & scientific | 2018 |
| BMS Geoengineering Services Ltd | Professional & scientific | 2017 |
| BN Fencing Holdings Ltd | Professional & scientific | 2022 |
| BN Fencing Investments Ltd | Professional & scientific | 2022 |
| BNR Joinery Services Limited | Construction | 2025 |
| BNT Consultants Limited | Professional & scientific | 2025 |
| BNT Logistics Ltd | Water & waste | 2025 |
| BNW Estates Ltd | Real estate | 2019 |
| BNW Renovations Ltd | Construction | 2025 |
| BO Hause Ltd | Real estate | 2019 |
| Boal’S Haulage Ltd | Education | 2025 |
| Bobby's African Carribean Asian Shop Ltd | Wholesale & retail | 2023 |
| Bobs Storage Boxes Ltd | Transport & logistics | 2025 |
| Boddy Contracting Limited | Professional & scientific | 2023 |
| Bodkin Events Ltd | Education | 2025 |
| Bogdanel Ivancea Logistics Limited | Transport & logistics | 2026 |
| Boho X Hospitality Limited | Administrative & support | 2023 |
| BOK BOK Books Ltd | Information & communication | 2018 |
| Bolckow Motor Mechanics & Vehicle Recovery Ltd | Wholesale & retail | 2025 |
| BON LEA Powder Coatings Limited | Manufacturing | 2017 |
| Bonad Innovations Limited | Health & social care | 2024 |
| Bonco K9 Ltd | Administrative & support | 2024 |
| Bond and Bloom Conceige Ltd | Administrative & support | 2026 |