| Blue Sky Investments 1 Limited | Real estate | 2025 |
| Blue Sky Surveys Ltd | Administrative & support | 2008 |
| Blue Star Recruitment Ltd | Administrative & support | 2022 |
| Blue Stripe Saucer Ltd | Extraterritorial | 2020 |
| Blue Tech Solutions Ltd | Information & communication | 2025 |
| Blue Venture Ltd | Wholesale & retail | 2024 |
| Bluebell Bakes Ltd | Wholesale & retail | 2026 |
| Blueberry Staffing Limited | Administrative & support | 2021 |
| Bluecube Cyber Security Solutions Limited | Information & communication | 2023 |
| Bluecube Group Limited | Financial services | 2023 |
| Bluecube Holdings Limited | Financial services | 2023 |
| Bluefeather Studios Limited | Wholesale & retail | 2016 |
| Bluefin Limited | Information & communication | 2017 |
| Bluelotusx Ltd | Wholesale & retail | 2018 |
| Bluemech Ltd | Wholesale & retail | 2005 |
| Bluemont Trading Ltd | Wholesale & retail | 2025 |
| Blueocean Property Services Limited | Real estate | 2021 |
| Bluepoint Corporation Limited | Manufacturing | 1992 |
| Bluepoint International Corporation Limited | Professional & scientific | 1994 |
| Blueprint MK Ltd | Administrative & support | 2024 |
| Blueprint Plumbing and Heating Limited | Construction | 2005 |
| Blues Healthcare Ltd | Health & social care | 2024 |
| Bluesatin Consulting Limited | Professional & scientific | 2022 |
| Bluescape Homes Limited | Construction | 2007 |
| Bluesell Services Limited | Real estate | 2016 |
| Bluewave Creative Limited | Wholesale & retail | 2026 |
| Bluewaves Car Wash Ltd | Wholesale & retail | 2025 |
| Bluewire Hub Ltd | Information & communication | 2014 |
| Bluewren Building Services Ltd | Construction | 2017 |
| Bluezeon Ltd | Information & communication | 2013 |
| Blum UK | Manufacturing | 1987 |
| Blush Bespoke Hair Salon Limited | Other services | 2021 |
| Blush Marketing Limited | Real estate | 2017 |
| Blushingflower Ltd | Hospitality | 2024 |
| BLX Tech Ltd | Information & communication | 2018 |
| Blyth Accounting Ltd | Professional & scientific | 2013 |
| Blythsinclair Business Solutions Ltd | Professional & scientific | 2023 |
| BLZ Textile Consulting Ltd | Wholesale & retail | 2021 |
| BM Agency Services Limited | Extraterritorial | 2001 |
| BM Clever Engineering Limited | Construction | 2018 |
| BM Elec and Co Ltd | Construction | 2024 |
| BM Foundry Ltd | Wholesale & retail | 2025 |
| BM Healthcare Services Ltd | Health & social care | 2019 |
| BM MK Ltd. | Arts & recreation | 2018 |
| BM Plastering &Building Solutions Ltd | Construction | 2023 |
| BMA Atelier Limited | Wholesale & retail | 2026 |
| Bmaa P2 Ltd | Education | 2020 |
| BMB Creative Ltd | Arts & recreation | 2013 |
| BMB Foods Ltd | Hospitality | 2026 |
| BMB Official Ltd | Health & social care | 2022 |
| BME MK Ltd | Wholesale & retail | 2026 |
| BMF BBQ Limited | Hospitality | 2026 |
| BMF Domestic and Industrial Ltd | Administrative & support | 2026 |
| BMG Technologies Limited | Wholesale & retail | 2007 |
| BMI Group Manufacturing UK Limited | Manufacturing | 1946 |
| BMI Group UK Limited | Manufacturing | 1990 |
| BMS Realtors Ltd | Real estate | 2022 |
| BMS Software Services Ltd | Information & communication | 2019 |
| BMX Information Systems (U.K.) Limited | Financial services | 1982 |
| BN Care Holdings Limited | Health & social care | 2022 |
| BNB ST Priest Ltd | Construction | 2025 |
| BNM Solutions Ltd | Real estate | 2025 |
| BO Blue Ltd | Information & communication | 2012 |
| Boardeli Sandwich Company Limited | Hospitality | 2023 |
| Boardrm Ltd | Administrative & support | 2017 |
| Boats for Cash Limited | Extraterritorial | 2006 |
| Boaz Services Limited | Financial services | 2011 |
| BOB Gibbs Financial Planning Limited | Financial services | 2015 |
| BOB International Services Ltd | Wholesale & retail | 2022 |
| Bobbing Along Limited | Arts & recreation | 2017 |
| Bobbyflash Limited | Professional & scientific | 2016 |
| Bobcole Venture Limited | Health & social care | 2020 |
| Bobo & Benny Ltd | Financial services | 2023 |
| Bobo Cool Ltd | Wholesale & retail | 2020 |
| Bobo Global Ltd | Wholesale & retail | 2019 |
| BOBO08 Ltd | Transport & logistics | 2025 |
| Bobolive Inc Ltd | Real estate | 2025 |
| Bobs and Bits 1989 Ltd | Wholesale & retail | 2026 |
| Boca Rica Foods Limited | Hospitality | 2018 |
| Boddy.Dev Ltd | Information & communication | 2026 |
| Bode UK & Ireland Ltd | Transport & logistics | 1999 |
| Body Sculpting by Sophie Ltd | Other services | 2025 |
| Bodyblendz UK Limited | Professional & scientific | 2025 |
| Bodycore Pilates Ltd | Health & social care | 2017 |
| Bodyfixers Automotive Repair Ltd | Wholesale & retail | 2020 |
| Bodykraft (Dudley) Limited | Manufacturing | 1998 |
| Bodykraft Merry Hill Limited | Manufacturing | 2004 |
| BOG Recovery Ltd | Other services | 2022 |
| Bogdan H Limited | Transport & logistics | 2018 |
| Bogus Trans Ltd | Transport & logistics | 2016 |
| Bohwaish Holdings Ltd | Construction | 2026 |
| Boinga Inflatables Ltd | Administrative & support | 2023 |
| Boipe Limited | Information & communication | 2023 |
| Bojar Property Ltd | Real estate | 2024 |
| Bokooo Ltd | Health & social care | 2022 |
| Bold Star Resources Limited | Wholesale & retail | 2013 |
| Boldface Editing Ltd | Information & communication | 2023 |
| Bollywood Junction Ltd | Hospitality | 2016 |
| Bollywood Social Club Limited | Education | 2022 |
| Bolocan Ltd | Construction | 2019 |