| B.E.L. Lift Trucks Limited | Wholesale & retail | 1950 |
| B.E.L. Properties Limited | Real estate | 1990 |
| B.G. Electrical (Northwest) Limited | Construction | 2013 |
| B.H. Accountancy Limited | Professional & scientific | 2008 |
| B.M. Fagleman Limited | Administrative & support | 2009 |
| B.Print & Display Limited | Manufacturing | 1981 |
| B.R Locums Ltd | Wholesale & retail | 2022 |
| B.U.N Inc Ltd | Hospitality | 2023 |
| B.Whittle Enterprises Ltd | Information & communication | 2019 |
| B1 Fitness Limited | Education | 2026 |
| B2B Cashflow Solutions Limited | Financial services | 2006 |
| B2B Commercials (NE) Limited | Administrative & support | 2021 |
| B2B Inspired Ltd | Manufacturing | 2019 |
| B2B Permanent Placements Ltd | Administrative & support | 2020 |
| B2B Property Solutions Limited | Real estate | 2012 |
| B2B Staff Solutions Ltd | Administrative & support | 2004 |
| B3I Limited | Real estate | 2016 |
| B4 Bathrooms Ltd | Construction | 2018 |
| B:Well Group CIC | Other services | 2019 |
| BA Essentials Limited | Wholesale & retail | 2026 |
| BA Flight Simulations Ltd | Arts & recreation | 2018 |
| BAB Software Solutions Limited | Information & communication | 2024 |
| Baba Nyonya Ltd | Hospitality | 2021 |
| Baba Property Holdings Limited | Real estate | 2026 |
| Babgulyas Ltd | Information & communication | 2024 |
| Babiechic Limited | Wholesale & retail | 2025 |
| Baby and Child Pension Trustee Limited | Financial services | 2023 |
| Baby's Kitchen Limited | Hospitality | 2026 |
| Babyled Food Ltd | Manufacturing | 2013 |
| Babys'N'Tot Ltd | Professional & scientific | 2018 |
| Babythingz Limited | Wholesale & retail | 2010 |
| Baccn (UK) Limited | Professional & scientific | 2003 |
| Back Page Shops Limited | Wholesale & retail | 2009 |
| Back ROW IM Limited | Professional & scientific | 2012 |
| BACK2LIFE Physiotherapy Ltd | Health & social care | 2021 |
| Backloop Ltd | Manufacturing | 2026 |
| Backworth 171819 Management Ltd | Households | 2018 |
| Backworth Miners Welfare Social Club Limited | Hospitality | 2004 |
| Backworth Park Management Company Limited | Real estate | 2017 |
| Backworth Quality Improvement Solutions Ltd | Public administration | 2014 |
| Backworth Takeaway Limited | Hospitality | 2019 |
| Bacta LAB Ltd | Professional & scientific | 2025 |
| BAD HAT Harry Ltd | Other services | 2013 |
| BAD Moon Media Ltd | Professional & scientific | 2016 |
| Bada Leisure Ltd | Hospitality | 2023 |
| BAG Primal Limited | Real estate | 2020 |
| Bagnall & Kirkwood Limited | Wholesale & retail | 1976 |
| Bahnasawi Ltd | Health & social care | 2025 |
| Bahr Academy | Education | 2010 |
| Bahuonline Limited | Wholesale & retail | 2025 |
| Baig Furnishing Ltd | Other services | 2021 |
| Bailey & Co. Limited | Real estate | 2013 |
| Bailey ST Georges Limited | Real estate | 2023 |
| Baines Construction (N.E.) Ltd | Construction | 2014 |
| Baines Developments Ltd | Construction | 2024 |
| Bairdtech Limited | Professional & scientific | 2017 |
| Bake Tutors Ltd | Education | 2022 |
| Bakehouse 78 Limited | Hospitality | 2024 |
| Baker Lightfoot & Co Limited | Other services | 2026 |
| Bakerboycouriers Ltd | Transport & logistics | 2025 |
| Bakers Fire Kitchen Ltd | Hospitality | 2026 |
| Bakes by H Ltd | Wholesale & retail | 2024 |
| Bala Homes Ltd | Construction | 2026 |
| Bala Services Ltd | Administrative & support | 2025 |
| Balag NCL Ltd | Education | 2021 |
| Balaji Wines Ltd | Wholesale & retail | 2017 |
| Balaz Restaurant Limited | Hospitality | 2019 |
| Balde Limited | Wholesale & retail | 2025 |
| Baldwin Scaffolding Limited | Construction | 2019 |
| Balfour Beatty Infrastructure Investments Limited | Professional & scientific | 1948 |
| Balfour Beatty Infrastructure Partners Member Limited | Professional & scientific | 2011 |
| Balfour Beatty Infrastructure Projects Investments Limited | Professional & scientific | 2010 |
| Balfour Beatty Investments Limited | Construction | 1989 |
| Balfour Beatty Ofto Holdings Limited | Professional & scientific | 2010 |
| Balfour Beatty Rail Corporate Services Limited | Professional & scientific | 1995 |
| Balfour Beatty Worksmart Limited | Administrative & support | 2010 |
| Balkassar Enterprises Limited | Wholesale & retail | 2025 |
| Ball Construction Ltd | Construction | 2020 |
| Ballantine Consulting Digital Marketing Ltd. | Professional & scientific | 2021 |
| Baller' Skin Limited | Manufacturing | 2022 |
| BALLER7 Limited | Manufacturing | 2019 |
| Ballet Lorent Limited | Arts & recreation | 2004 |
| Balliol Court Property Management Limited | Real estate | 2004 |
| Balloons 4 YOU Ltd | Wholesale & retail | 2010 |
| Ballpoint Films Ltd | Information & communication | 2021 |
| Ballyleary Holdings Limited | Real estate | 2018 |
| Balmbra's Investments Limited | Extraterritorial | 2023 |
| Balmoral Education Limited | Education | 2014 |
| Balti House NE Ltd | Hospitality | 2024 |
| BAM Spice Ltd | Hospitality | 2020 |
| Bambi Property Limited | Real estate | 2019 |
| Bamboo Engineering Limited | Arts & recreation | 2009 |
| Bamboo Milk Tea Limited | Wholesale & retail | 2023 |
| Bamburgh Apartment Holidays Ltd | Real estate | 2026 |
| Bana Darwich Interiors Limited | Professional & scientific | 2020 |
| Banat Ltd | Health & social care | 2011 |
| Bancroft Court Management Henshaw Lane Ltd | Real estate | 2021 |
| Band of Climbers Travel Ltd | Administrative & support | 2019 |
| Bandronks Store Ltd | Wholesale & retail | 2025 |
| Bandstand Exhibition Park Ltd | Hospitality | 2026 |