| Build Solutions Ltd | Construction | 2018 |
| Buildbird Ltd | Information & communication | 2025 |
| Builders&Gardeners Limited | Construction | 2023 |
| Building Futures East Limited | Other services | 2007 |
| Building Maintenance Services North East Limited | Construction | 2006 |
| Building Software Services (UK) Limited | Information & communication | 2016 |
| Building Surveyors Limited | Professional & scientific | 2003 |
| Building UK & Maintenance Service Limited | Construction | 2023 |
| Building Wealth Management Limited | Real estate | 2017 |
| Building Work by ABU Ltd | Construction | 2025 |
| Buildne Group Ltd | Information & communication | 2026 |
| Buildscape Builders Ltd | Construction | 2024 |
| Buildworks North East Ltd. | Construction | 2017 |
| Built to Last Electrical Solutions LLP | | 2026 |
| Built With Irons Ltd | Arts & recreation | 2025 |
| Bukhari Services NE Ltd | Administrative & support | 2020 |
| Bukola Holdings Ltd | Real estate | 2024 |
| Buku Tech Limited | Information & communication | 2020 |
| Bulien LLP | | 2019 |
| Bulldog Gosforth Ltd | Construction | 2023 |
| Bulldog Kitchens Ltd | Construction | 2019 |
| Bulldog Premium Growth I Limited | Professional & scientific | 1993 |
| Bulldog Properties Ltd | Real estate | 2020 |
| Bullfrog Living Ltd | Real estate | 2016 |
| Bullion Customs Ltd | Wholesale & retail | 2025 |
| Bulman Support Ltd | Professional & scientific | 2013 |
| Bulmer Interior Contracts Limited | Construction | 1981 |
| Bulut TEK Limited | Information & communication | 2024 |
| Bulwer Invest LP | | 2017 |
| Buma Engineering Company Limited | Water & waste | 1941 |
| Bumbl Creative Limited | Professional & scientific | 2017 |
| Bunhill Services Limited | Education | 2005 |
| Bunker Thirteen | Real estate | 2009 |
| Bunns Cakes and Bakes Ltd | Wholesale & retail | 2016 |
| Bunny Rwlk Ltd | Arts & recreation | 2024 |
| Bunse Holding Limited | Financial services | 2018 |
| Burdon Green (Coxhoe) Management Company Limited | Households | 2020 |
| Burdon Lane (Ryhope) Residents Management Company Limited | Real estate | 2023 |
| Burdon Rise Residents Management Company Limited | Households | 2019 |
| Burds Jesmond Limited | Hospitality | 2020 |
| Burger Bros NE Limited | Hospitality | 2025 |
| Burger World 1 Ltd | Hospitality | 2023 |
| Burgerandspice Ltd | Hospitality | 2025 |
| Burgerdrop Plus Ltd | Wholesale & retail | 2025 |
| Burgersbybrad Limited | Wholesale & retail | 2025 |
| Burgham Horse Trials Ltd | Arts & recreation | 2010 |
| Burledon Limited | Professional & scientific | 2017 |
| Burley House Leeds Limited | Extraterritorial | 1976 |
| Burmac Limited | Construction | 2012 |
| Burn Haulage (Contracts) Ltd | Construction | 1988 |
| Burnopfield Contract Hire Ltd | Transport & logistics | 2017 |
| Burnopfield Fastfit & Tyres Ltd | Wholesale & retail | 2025 |
| Burnopfield Metals Ltd | Wholesale & retail | 2024 |
| Burnopfield Properties (NE) Ltd | Real estate | 2024 |
| Burnopfield Properties Limited | Professional & scientific | 1970 |
| Burnout Boxing Limited | Arts & recreation | 2024 |
| Burns Creative Ltd | Information & communication | 2019 |
| Burns Rentals Limited | Construction | 2015 |
| Burnshaws Limited | Administrative & support | 2024 |
| Burnside Properties Ltd | Real estate | 2026 |
| Burr Living One Limited | Construction | 2014 |
| Burradon Meds Limited | Wholesale & retail | 2025 |
| Burraq Properties Limited | Real estate | 2025 |
| Burraq Systems Ltd | Information & communication | 2024 |
| Burrows Scaffolding Ltd | Construction | 2025 |
| BUS UK Limited | Extraterritorial | 1988 |
| Buscall Limited | Transport & logistics | 1999 |
| Bushnell Limited | Other services | 1991 |
| Business Box Units Limited | Construction | 2019 |
| Business Business Limited | Financial services | 2020 |
| Business Development Performance Ltd | Professional & scientific | 2015 |
| Business Energy Claims Limited | Professional & scientific | 2018 |
| Business Energy Helpline UK Ltd | Other services | 2018 |
| Business Mentoring Solutions Limited | Professional & scientific | 2021 |
| Business Solutions and Services Europe Ltd | Information & communication | 2026 |
| Business Switch GAS and Electric Limited | Professional & scientific | 2018 |
| Business Technology Innovations Limited | Information & communication | 2015 |
| Business Wear Direct Ltd | Wholesale & retail | 2018 |
| Bustle Technologies Ltd | Transport & logistics | 2026 |
| Buston Group Limited | Professional & scientific | 2024 |
| Busy SPR Ltd | Education | 2002 |
| Butama Ltd | Health & social care | 2025 |
| Butler Financial Services Limited | Financial services | 2012 |
| Butterfield Physiotherapy Limited | Health & social care | 2011 |
| Butterfli Technology Group Ltd | Professional & scientific | 2020 |
| Butterflies and Bugs Limited | Other services | 2012 |
| Butterfly Bridal Boutique Limited | Wholesale & retail | 2010 |
| Butterfly Effect Label Limited | Hospitality | 2023 |
| Butterfly Lexi Limited | Other services | 2019 |
| Butterfly Offshore Services Ltd | Administrative & support | 2018 |
| Buttermere Limited | Construction | 2021 |
| Butterscotch Event Designers Ltd | Administrative & support | 2023 |
| Butterworth Laser and Surgery Ltd | Health & social care | 2026 |
| Buttie-Licious Limited | Wholesale & retail | 2017 |
| Buttonenergy Limited | Other services | 2003 |
| Butumbi Business Limited | Transport & logistics | 2024 |
| Buy ANY Tool Limited | Wholesale & retail | 2020 |
| Buying Zone Ltd | Wholesale & retail | 2022 |
| Buyskys Limited | Wholesale & retail | 2021 |
| Buzz Private Only Ltd | Transport & logistics | 2026 |