| Askew Property Ltd | Real estate | 2025 |
| ASL Renewables Limited | Construction | 2022 |
| Aspin Aesthetics Ltd | Health & social care | 2022 |
| Aspire Digital Marketing Ltd | Professional & scientific | 2019 |
| Aspire Prep Limited | Education | 2025 |
| Asset Competency Management Ltd | Manufacturing | 2009 |
| Ataraxia Solutions Limited | Real estate | 2025 |
| Atcom (Cambs) Limited | Real estate | 1998 |
| Atex Services Limited | Construction | 2019 |
| Atlas Overland Limited | Arts & recreation | 2010 |
| Atworth Engineering Limited | Construction | 2014 |
| Auld Cross Keys Inn EOT Limited | Financial services | 2025 |
| Auld Joe's Limited | Real estate | 2025 |
| Aurum Realty Property Ltd | Real estate | 2026 |
| Authentix Management Limited | Information & communication | 2021 |
| Autobahn (Hexham) Limited | Wholesale & retail | 2006 |
| Autostar Interface Limited | Information & communication | 2008 |
| Auviv Limited | Manufacturing | 2000 |
| Avenda Estates Limited | Real estate | 2004 |
| Awakened Beauty Limited | Other services | 2014 |
| AWS Agri Ltd | Wholesale & retail | 2018 |
| Aydon Shields Ltd | Construction | 2015 |
| Aztec Skincare Ltd | Manufacturing | 2022 |
| B W Electrical Solutions Limited | Other services | 2010 |
| Bacit Software Services Ltd | Wholesale & retail | 2024 |
| BAD Press INK Limited | Information & communication | 2017 |
| Bad-Press.Co.Uk Limited | Information & communication | 2000 |
| Baker Brown Management Limited | Professional & scientific | 2025 |
| Balman Gallery Limited | Arts & recreation | 2009 |
| Balmer Holdings One Ltd | Real estate | 2024 |
| Balmer Holdings Two Limited | Real estate | 2026 |
| Bark Boxes Limited | Manufacturing | 2020 |
| Barrasford Park Limited | Real estate | 2010 |
| Barrasford Park Properties Limited | Real estate | 2019 |
| Barrow Shipping Limited | Energy | 2012 |
| Bastille Holdings Ltd | Real estate | 2020 |
| Bastronomy Ltd | Hospitality | 2023 |
| Battery Energy Systems Ltd | Construction | 2017 |
| Bauer Electrical & Testing Limited | Construction | 2011 |
| Bauer Solar Limited | Construction | 2024 |
| Baxters Exterior Cleaning Ltd | Administrative & support | 2021 |
| BE Wild About Adventure Ltd | Education | 2023 |
| Beatson Clark Consulting Limited | Professional & scientific | 2024 |
| Beaufront Woodhead Management Company Limited | Extraterritorial | 1999 |
| Beaumont Leaf Limited | Professional & scientific | 2018 |
| Beaumont Supported Living Holdings Limited | Health & social care | 2009 |
| Becks Group Limited | Professional & scientific | 2019 |
| Beehive Property Limited | Real estate | 2016 |
| Behind the Hedge Limited | Professional & scientific | 2021 |
| Bellingham Camping Limited | Hospitality | 2013 |
| Bellingham Wine Store Limited | Wholesale & retail | 2024 |
| Bellscott Living Limited | Hospitality | 2021 |
| Belton Projects Ltd | Construction | 2020 |
| BEN TOV Newton PDE Ltd | Real estate | 2018 |
| Bents Meadow Shepherds Huts Limited | Hospitality | 2022 |
| Bespoke Financial Wellbeing Ltd | Professional & scientific | 2021 |
| Birkshaw Consulting Ltd | Professional & scientific | 2026 |
| Birney Companies Limited | Wholesale & retail | 2007 |
| Bix's Wheels Ltd | Transport & logistics | 2026 |
| Black INK Holdings Limited | Wholesale & retail | 2021 |
| Black Reiver Consulting Ltd | Agriculture & fishing | 2012 |
| Blistered Productions Limited | Information & communication | 2023 |
| Blockworksuk Ltd | Manufacturing | 2025 |
| Bloodaxe Books Limited | Information & communication | 1982 |
| Blue Green Engineering Ltd | Professional & scientific | 2011 |
| Blueface Consulting Limited | Professional & scientific | 2005 |
| Board School Developments Limited | Real estate | 2024 |
| Bobo Clinic Limited | Wholesale & retail | 2022 |
| Bobz Bearz Limited | Wholesale & retail | 2025 |
| Border Craft Group Ltd | Administrative & support | 2011 |
| Border Craft Homes Ltd | Construction | 2023 |
| Border Forest Caravan Park Limited | Extraterritorial | 2014 |
| Borders Recycling Limited | Water & waste | 2004 |
| Bouchon Restaurant Limited | Hospitality | 2007 |
| Bowman Homes Limited | Construction | 2017 |
| Bradshawnet Limited | Professional & scientific | 2013 |
| Branton Farming Ltd | Administrative & support | 2009 |
| Brave Location Services Ltd | Information & communication | 2024 |
| Breckon Hill Management Limited | Households | 2019 |
| Brian Nichol (Wark) Limited | Construction | 1967 |
| Bridge Club Limited | Administrative & support | 2001 |
| Bright Sparke Ventures Limited | Professional & scientific | 2012 |
| Brightworx Consulting Limited | Information & communication | 2022 |
| Brisco ENG LLP | | 2019 |
| Britshopping Ltd | Wholesale & retail | 2024 |
| Britton Construction NE Limited | Construction | 2010 |
| Bryony's Botanicals Ltd | Manufacturing | 2024 |
| BT Bell Associates Limited | Professional & scientific | 1998 |
| Btcs Nominees Limited | Financial services | 2007 |
| BTJ Developments Limited | Real estate | 2006 |
| Built Infrastructure Solutions Limited | Construction | 2013 |
| Burn Brae House Management Company Limited | Real estate | 2016 |
| Burncliffe Electrical Limited | Construction | 2001 |
| Burnlaw Centre CIC | Hospitality | 2011 |
| Burnside Allenheads Ltd | Hospitality | 2019 |
| Business Angel Holding Company Limited | Financial services | 2024 |
| Business IS Humans Ltd | Professional & scientific | 2025 |
| Busy.Beezz Ltd | Administrative & support | 2022 |
| Buteland Farm Management Company Limited | Real estate | 2007 |
| BY the River (North East) Limited | Hospitality | 2019 |