| BH13 Construction Project Managers Ltd | Construction | 2009 |
| BH14 Rental Limited | Real estate | 2025 |
| BH17 Ltd | Hospitality | 2023 |
| BH23EXEC Ltd | Administrative & support | 2018 |
| BH24 Consulting Limited | Transport & logistics | 2020 |
| Bhanuba Ltd | Wholesale & retail | 2026 |
| Bharat Solutions Ltd | Information & communication | 2024 |
| BHC Global Ltd | Wholesale & retail | 2019 |
| Bhdo Limited | Wholesale & retail | 2014 |
| BHH Tech Ltd | Information & communication | 2019 |
| BHK Store Ltd | Wholesale & retail | 2025 |
| Bianca Maria Aesthetics Limited | Other services | 2022 |
| Bianco Management Company Limited | Real estate | 2011 |
| Bias Technology Support Limited | Information & communication | 2008 |
| Bichip Store Ltd | Financial services | 2021 |
| Bifrost Development Ltd | Information & communication | 2026 |
| Big Bear Supplies Ltd | Wholesale & retail | 2017 |
| Big Culture Music Ltd | Arts & recreation | 2016 |
| Big Data Analytics Limited | Information & communication | 2013 |
| Big Golden Pineapple Limited | Professional & scientific | 2020 |
| Big Ideas Product Development Limited | Arts & recreation | 1999 |
| Big MAN On-Chain Ltd | Information & communication | 2025 |
| Big Organisation Ltd | Information & communication | 2022 |
| Big RIB Charters Cornwall LLP | | 2015 |
| Big River Agency Ltd | Wholesale & retail | 2005 |
| Big School Capital Ltd | Financial services | 2022 |
| Big T Ltd | Financial services | 2025 |
| Big Things Service Limited | Transport & logistics | 2024 |
| Big Warranties Limited | Financial services | 2009 |
| Big ‘N’ Little Laundry Limited | Other services | 2018 |
| Bigcrea Limited | Information & communication | 2023 |
| Bigmart Stores Ltd | Wholesale & retail | 2025 |
| Bike BUS Ltd | Information & communication | 2023 |
| Bilene Limited | Financial services | 2019 |
| Billybob Limited | Construction | 2010 |
| Binary Pulsar Ltd. | Information & communication | 2016 |
| Binary Sentience Ltd | Information & communication | 2020 |
| Bindbops Ltd | Information & communication | 2020 |
| Bindon Abbey Scaffolding Limited | Construction | 2013 |
| Bindon Engineering Company Limited | Professional & scientific | 1966 |
| Binga Holdings Ltd | Professional & scientific | 2019 |
| Binti 9 Ltd | Wholesale & retail | 2019 |
| Bintia Ltd | Information & communication | 2010 |
| Biogas Cover Limited | Construction | 2023 |
| Biographies Limited | Wholesale & retail | 2016 |
| Bionanovate Limited | Real estate | 2002 |
| Biosirius Ltd | Manufacturing | 2021 |
| Bioyogicaherbls Ltd | Wholesale & retail | 2024 |
| Biped Design Ltd | Professional & scientific | 2017 |
| Birch Financial Services Ltd | Professional & scientific | 2008 |
| Birchmere Development Holdings Limited | Real estate | 2020 |
| Birchmere Developments Limited | Real estate | 2020 |
| Birchmere Holdings Limited | Real estate | 2020 |
| Birchmere Limited | Real estate | 1975 |
| Birchwood Management Company Limited | Real estate | 2007 |
| Birchwood Private Physiotherapy Poole Ltd. | Health & social care | 2014 |
| Birdsong Consulting Ltd | Professional & scientific | 2023 |
| Birks Electrical Contractors Limited | Construction | 1996 |
| Birsoft Limited | Information & communication | 2024 |
| Birthed Coaching and Mentoring Ltd. | Professional & scientific | 2021 |
| Bishop's Property Maintenance Ltd | Construction | 2020 |
| Bishopside Builders Limited | Construction | 2023 |
| Bistoury Medical Limited | Health & social care | 2020 |
| BIT Robotics Ltd | Information & communication | 2018 |
| BITB2B Limited | Information & communication | 2016 |
| Bite and Chill Ltd | Manufacturing | 2025 |
| Bitten LIP Clothing Ltd | Extraterritorial | 2020 |
| Bitten LIP Ltd | Wholesale & retail | 2020 |
| BITZZ4U Ltd | Wholesale & retail | 2024 |
| Biyode Ltd | Wholesale & retail | 2025 |
| Bizmax Group Ltd | Information & communication | 2021 |
| Bizpa Limited | Administrative & support | 2015 |
| Bizzupi Ltd. | Professional & scientific | 2024 |
| Bizzybeez Childcare Ltd | Health & social care | 2023 |
| BJB Construction Limited | Construction | 2022 |
| BKB Accountants Ltd | Professional & scientific | 2003 |
| BKB Holdings Ltd | Financial services | 2021 |
| BKB Payroll Ltd | Professional & scientific | 2022 |
| BKM Living Ltd | Real estate | 2026 |
| Bkpc Construction Limited | Construction | 2023 |
| Blacc Shadow Studios Limited | Information & communication | 2026 |
| Black Cat Bridal Ltd | Wholesale & retail | 2022 |
| Black Diamond Lifestyle Limited | Wholesale & retail | 2010 |
| Black Dog Communications Ltd | Information & communication | 2012 |
| Black Dog Genus Ltd | Financial services | 2024 |
| Black Dog Precision Limited | Manufacturing | 2025 |
| Black Dog Strategies Ltd | Real estate | 2023 |
| Black Dog Structura Ltd | Households | 2024 |
| Black Ember Ltd | Manufacturing | 2025 |
| Black Gold Developments (UK) Limited | Construction | 2005 |
| Black Isle Holdings Limited | Wholesale & retail | 2024 |
| Black Label Wealth Management Ltd | Financial services | 2015 |
| Black Magick Dirah Ltd | Other services | 2021 |
| Black Peek Consulting Ltd | Professional & scientific | 2025 |
| Black Robin Exhibits Limited | Administrative & support | 2019 |
| Black Stone Fort (Gervis) Limited | Real estate | 2018 |
| Black Sunflowers Poetry Press Ltd | Information & communication | 2021 |
| Black Tide Lures Ltd | Wholesale & retail | 2024 |
| Blackbeard Holdings Limited | Financial services | 2021 |
| Blackbird Estates Limited | Real estate | 2003 |