| BLG Secure Delivery Ltd | Transport & logistics | 2021 |
| Blink Web Design Limited | Information & communication | 2016 |
| Blinknow Limited | Professional & scientific | 2010 |
| Bloc North East Ltd | Real estate | 2026 |
| Block 11 Limited | Hospitality | 2016 |
| Block and Bottle Ltd | Wholesale & retail | 2016 |
| Blockchain Pharma Limited | Information & communication | 2021 |
| Blocknorth Ltd | Information & communication | 2018 |
| Blocks Medical Accountants Ltd | Professional & scientific | 2021 |
| Blond Ambition Limited | Real estate | 2024 |
| Blood Moon Games Ltd | Information & communication | 2019 |
| Bloom Digital Limited | Information & communication | 2020 |
| Bloom Wellbeing Training Ltd | Education | 2024 |
| Bloombridge Gardens Ltd | Administrative & support | 2026 |
| Bloomfield Associates Limited | Real estate | 2006 |
| Blooming Flowers NE Ltd | Wholesale & retail | 2025 |
| Blooms Aura Limited | Professional & scientific | 2025 |
| Blossomwood Property Ltd | Real estate | 2019 |
| Blots Toys Limited | Wholesale & retail | 2018 |
| Blowin' a Hooley Theatre Limited | Arts & recreation | 2018 |
| Blowtech Marine Services Ltd | Other services | 2026 |
| BLT Asset Management Limited | Administrative & support | 2020 |
| BLT Contracts Limited | Transport & logistics | 2021 |
| BLT Prop Co Limited | Real estate | 2024 |
| BLU Print Design Limited | Professional & scientific | 2008 |
| Blucher Community Boxing Club CIC | Arts & recreation | 2025 |
| Blue Anchor Residents Association Limited | Households | 1987 |
| Blue and Lintell Limited | Information & communication | 2026 |
| Blue Box Training & Development Limited | Professional & scientific | 2003 |
| Blue Business Water Limited | Water & waste | 2014 |
| Blue Cloud IT Limited | Information & communication | 2008 |
| Blue Cookie Limited | Information & communication | 2015 |
| Blue Eternally Limited | Professional & scientific | 2025 |
| Blue Fish S&A Limited | Information & communication | 2011 |
| Blue Flame Heating Services Limited | Wholesale & retail | 2007 |
| Blue Flames Sporting Club Limited | Arts & recreation | 1996 |
| Blue Folder Management Ltd. | Construction | 2017 |
| Blue Green Group Ltd | Professional & scientific | 2023 |
| Blue Green World Ltd | Professional & scientific | 2025 |
| Blue House Living Limited | Real estate | 2018 |
| Blue House Properties (North East) Limited | Real estate | 2013 |
| Blue Kangaroo Creations Limited | Extraterritorial | 2025 |
| Blue Kangaroo Design Holdings Limited | Extraterritorial | 2016 |
| Blue Kangaroo Design Limited | Arts & recreation | 2006 |
| Blue Kangaroo Management Limited | Professional & scientific | 2012 |
| Blue Keys Property Ltd | Real estate | 2023 |
| Blue Leaf Energy Services Ltd | Construction | 2021 |
| Blue Line (North East) Ltd | Transport & logistics | 2013 |
| Blue Line Call Centre Services Ltd | Transport & logistics | 2020 |
| Blue Loft Properties Ltd | Administrative & support | 2017 |
| Blue MAN NE Limited | Real estate | 2025 |
| Blue Marvel Management Limited | Construction | 2020 |
| Blue Marvel Technologies Limited | Information & communication | 2024 |
| Blue Moon Traders Limited | Wholesale & retail | 2022 |
| Blue Note Property Limited | Real estate | 2020 |
| Blue Ocean Textile Ltd | Manufacturing | 2015 |
| Blue Onion AI Ltd | Information & communication | 2025 |
| Blue Optical Limited | Wholesale & retail | 2019 |
| Blue Orchid Living Limited | Real estate | 2019 |
| Blue Property Investments (NE) Limited | Construction | 2021 |
| Blue Property Solutions Ltd | Real estate | 2020 |
| Blue Rain Productions Ltd | Professional & scientific | 2007 |
| Blue Shark Design Limited | Professional & scientific | 2002 |
| Blue Shop NE Ltd | Wholesale & retail | 2024 |
| Blue Shop Store Ltd | Wholesale & retail | 2026 |
| Blue Sky Entertainment Ltd | Hospitality | 2015 |
| Blue Square Utilities Ltd | Construction | 2017 |
| Blue Star Football Limited | Arts & recreation | 2018 |
| Blue Star Interiors North East Limited | Construction | 2022 |
| Blue Star Scaffolding NE Ltd | Construction | 2026 |
| Blue Star Thistle Ltd | Financial services | 2025 |
| Blue Triangle Buses Limited | Professional & scientific | 1999 |
| Blue Wave Training & Consultancy Ltd | Education | 2019 |
| Blue Waves Marine Ltd | Administrative & support | 2026 |
| Bluebell Blinds (Newcastle) Ltd | Construction | 2017 |
| Bluebell Dene RTM Company Ltd | Households | 2026 |
| Bluebell Gardens Management Company Limited | Real estate | 2024 |
| Bluegrass Research Limited | Professional & scientific | 2007 |
| Bluekeep Building Control Limited | Administrative & support | 2007 |
| Bluemotion Automotive Group Ltd | Wholesale & retail | 2023 |
| Bluemotionmotorcompany Limited | Wholesale & retail | 2017 |
| Blueoak Innovations Ltd | Information & communication | 2025 |
| Blueprint Systems Ltd | Professional & scientific | 2025 |
| Blues and Bourbon NE Ltd | Education | 2022 |
| Blueskies Simulators Ltd | Arts & recreation | 2020 |
| Bluesky (Northeast) 3 Limited | Professional & scientific | 2014 |
| Bluestar Global Medical Services Ltd | Other services | 2023 |
| Blyth & Blyth Ltd | Real estate | 2026 |
| Blyth Fish Limited | Wholesale & retail | 2010 |
| Blyth Investments LLP | | 2010 |
| Blyth Medtech Limited | Information & communication | 2023 |
| Blyth Property Investments Limited | Construction | 2014 |
| BM Auto Centre Ltd | Wholesale & retail | 2026 |
| BM Blake Building Solutions Ltd | Construction | 2026 |
| BMB UK Partners Limited | Information & communication | 2026 |
| BMB5 Direct Ltd | Wholesale & retail | 2022 |
| BMC Cultural Exchange Limited | Other services | 2015 |
| BMC Property Investment Ltd | Real estate | 2026 |
| BMC Recruitment Group Ltd | Administrative & support | 2013 |
| BME Engineering Ltd | Manufacturing | 2026 |