| B & K News Ltd | Wholesale & retail | 2017 |
| B & M Construction and Property Developments UK Limited | Construction | 2025 |
| B & P Secretarial Services Ltd | Professional & scientific | 2017 |
| B & S Curtains Limited | Manufacturing | 2006 |
| B & S Developments Limited | Administrative & support | 2011 |
| B &G Car Sales Ltd | Wholesale & retail | 2024 |
| B - Shone Cleaning Services Ltd | Administrative & support | 2022 |
| B a Shopfittings Limited | Manufacturing | 2002 |
| B B H Hydraulics Limited | Manufacturing | 2003 |
| B Brill Plumbing and Heating Ltd | Construction | 2016 |
| B C Motors Limited | Wholesale & retail | 2025 |
| B in Tune Ltd | Professional & scientific | 2023 |
| B Kuang Ltd | Wholesale & retail | 2023 |
| B Lynott Properties Limited | Real estate | 2023 |
| B M Pest Solutions Limited | Administrative & support | 2005 |
| B R K (UK) Limited | Manufacturing | 2008 |
| B Realisations 2026 Limited | Wholesale & retail | 2004 |
| B S I International Limited | Wholesale & retail | 1981 |
| B Sherman Limited | Information & communication | 2010 |
| B T Trimmings & Packaging Limited | Administrative & support | 2010 |
| B Thompson Consultancy Ltd | Professional & scientific | 2015 |
| B&A Painting and Decorating Services Ltd | Construction | 2025 |
| B&C Healthcare Limited | Health & social care | 2022 |
| B&K Express & Sons Ltd | Wholesale & retail | 2018 |
| B&K Property Investment Ltd | Real estate | 2021 |
| B&K SON Property Holding Ltd | Real estate | 2024 |
| B&N Engineering Solutions Ltd | Professional & scientific | 2024 |
| B&N Recovery Ltd | Transport & logistics | 2025 |
| B&O Ltd | Other services | 2019 |
| B&P General Services Ltd | Construction | 2026 |
| B&S IT Solutions Limited | Information & communication | 2015 |
| B&V Transport Ltd | Transport & logistics | 2019 |
| B-Town Restaurant Limited | Real estate | 2015 |
| B. & C. Music Publishing Limited | Other services | 1994 |
| B. Scurry Limited | Construction | 2010 |
| B.E. Property (MK) Ltd | Real estate | 2014 |
| B.E.L.L.E Inc Ltd | Wholesale & retail | 2021 |
| B.O.G Trustee Limited | Professional & scientific | 2015 |
| B.O.S.S Acting LLP | | 2023 |
| B.P.S. Plastics Limited | Professional & scientific | 1999 |
| B.P.Singh Transport Ltd | Transport & logistics | 2025 |
| B.Style Ltd | Construction | 2016 |
| B.U Studio Aesthetics Limited | Other services | 2026 |
| B1UE U Limited | Administrative & support | 2020 |
| B2B Lead Agency Limited | Wholesale & retail | 2012 |
| B2R Property Services Ltd | Real estate | 2025 |
| B2R Solutions Limited | Real estate | 2017 |
| B3 Partnership Limited | Other services | 2006 |
| B3A Consulting Ltd | Information & communication | 2016 |
| B4 Property Solutions Ltd | Real estate | 2021 |
| B:Executive MK Ltd | Administrative & support | 2020 |
| BA Telecoms Ltd | Other services | 2021 |
| BAA Global Ltd | Wholesale & retail | 2018 |
| Baan Business Solutions Ltd | Wholesale & retail | 2018 |
| Baank Ltd | Administrative & support | 2008 |
| Baast Creative Limited | Wholesale & retail | 2021 |
| Babadel Estates Limited | Real estate | 2026 |
| Babbitt Limited | Education | 2009 |
| Baby Republic Limited | Wholesale & retail | 2014 |
| Baby Safe Ltd | Manufacturing | 2015 |
| Baby Sling Fit Ltd | Arts & recreation | 2018 |
| Baby Swimming Bedford LLP | | 2016 |
| Babyology Nutrition & Wellness Limited | Wholesale & retail | 2026 |
| BAC Business Management Services Limited | Professional & scientific | 2017 |
| Baciu Vasile Ltd | Transport & logistics | 2022 |
| Back on Track Physiotherapy Ltd | Administrative & support | 2006 |
| Backdraft Limited | Wholesale & retail | 2006 |
| Backstage Dance & Bridalwear Limited | Wholesale & retail | 1997 |
| Backstage Milton Keynes Limited | Wholesale & retail | 1982 |
| Backstreets Entertainment Limited | Arts & recreation | 2021 |
| Backup Logistics Limited | Transport & logistics | 2022 |
| Bacteriworx Ltd | Other services | 2023 |
| BAD at Golf Limited | Information & communication | 2024 |
| Badface Ltd | Wholesale & retail | 2024 |
| Badger Designer Ltd | Construction | 2024 |
| Badminton GB Limited | Administrative & support | 2000 |
| Badoi Logistics Ltd | Manufacturing | 2026 |
| Badsey Homes Limited | Construction | 2015 |
| Badsha BD Ltd | Construction | 2026 |
| Bafflow Rollcline Limited | Professional & scientific | 2024 |
| Bagels 'N' Bits Limited | Hospitality | 2021 |
| Baglu Property Ventures Limited | Real estate | 2024 |
| Bago Care Limited | Administrative & support | 2015 |
| Bags of Choice Limited | Households | 1976 |
| Bahadur Brothers Limited | Professional & scientific | 2015 |
| Bahnan Unique Solution Ltd | Public administration | 2020 |
| Bahria Ltd | Information & communication | 2026 |
| Baidu Apollo International UK Limited | Transport & logistics | 2026 |
| Bailey MK Limited | Construction | 2013 |
| Bailey Roofing MK Ltd | Extraterritorial | 2020 |
| Bailey Weber Limited | Manufacturing | 2006 |
| Bailey's Investments Properties Group Ltd | Financial services | 2024 |
| Bailey's Investments Properties Ltd | Households | 2024 |
| Baileys (AS) Ltd | Professional & scientific | 2013 |
| Bait Bandits Limited | Agriculture & fishing | 2025 |
| Bajgin Ltd | Wholesale & retail | 2025 |
| Baked by K Ltd | Hospitality | 2025 |
| Baker Small Legal Services Ltd | Professional & scientific | 2010 |
| Bakers + Baristas UK Limited | Hospitality | 2009 |
| Bakers Developments Limited | Construction | 2025 |