| BJD Solutions Ltd | Real estate | 1976 |
| BJM Pressure Washing Ltd | Administrative & support | 2023 |
| Bjulie Limited | Construction | 2021 |
| Bjwalker Properties Ltd | Real estate | 2020 |
| BK Compassionate Care Ltd | Public administration | 2025 |
| BK Estates Ltd | Real estate | 2005 |
| BK Johal & Sons Ltd | Real estate | 2017 |
| BK Manufacturers Ltd | Manufacturing | 2023 |
| BK Travels Ltd | Transport & logistics | 2023 |
| BKS Consultancy Services Ltd | Professional & scientific | 2021 |
| Bksr Limited | Hospitality | 2024 |
| Black Bull Preston Limited | Hospitality | 2023 |
| Black Castle Property Management Ltd | Real estate | 2023 |
| Black Diamond Management Limited | Professional & scientific | 2013 |
| Black Dyke Mills Band Limited | Extraterritorial | 1971 |
| Black Dyke Mills Heritage Venue CIC | Arts & recreation | 2020 |
| Black Horse Spares Ltd | Wholesale & retail | 2023 |
| Black Label Clothes Limited | Wholesale & retail | 2019 |
| Black Line Heritage CIC | Administrative & support | 2022 |
| Black Marble Limited | Information & communication | 1997 |
| Black Moose Property Limited | Real estate | 2019 |
| Black on Board Ltd | Professional & scientific | 2020 |
| Black OPS Nutrition Ltd | Manufacturing | 2025 |
| Black Rock Environmental Associates Limited | Water & waste | 1998 |
| Black Security Limited | Administrative & support | 2025 |
| Black Shield Security Ltd | Financial services | 2025 |
| Black Star Games Ltd | Wholesale & retail | 2019 |
| Blackbat Limited | Wholesale & retail | 2024 |
| Blackbeard Investment Ltd | Real estate | 2024 |
| Blackberry Marketing Limited | Administrative & support | 2023 |
| Blackdiamondaerosols Ltd | Wholesale & retail | 2019 |
| Blackdrop Ltd | Health & social care | 2021 |
| Blackgaates Inc Limited | Construction | 2019 |
| Blackhorse Property Group Ltd | Real estate | 2020 |
| Blackhorse Property Ltd | Real estate | 2019 |
| Blackhorse Property Management Ltd | Real estate | 2023 |
| Blackjack PUB Company Limited | Hospitality | 2024 |
| Blackout Fitness Studio Ltd | Arts & recreation | 2026 |
| Blackout Response Ltd | Construction | 2023 |
| Blackpool Resin Drives Ltd | Administrative & support | 2023 |
| Blacksmith Holdings (2021) Limited | Financial services | 2021 |
| Blackspider Academy Limited | Arts & recreation | 2021 |
| Blackstone & Landrock Ltd | Real estate | 2025 |
| Blackstone BFD Property Limited | Real estate | 2023 |
| Blackstone Estate Group Ltd | Real estate | 2025 |
| Blackstone Law Services Ltd | Professional & scientific | 2023 |
| Blackthorn Inns Ltd. | Hospitality | 2009 |
| Blacktick Limited | Manufacturing | 2003 |
| Blade Access Ltd | Construction | 2012 |
| Blade Access SP Ltd | Construction | 2018 |
| Blade Assets Ltd. | Administrative & support | 2021 |
| Blade Facilities Management LLP | | 2010 |
| Blade Lifting and Logistics Limited | Construction | 2025 |
| Blade Roofing Ltd | Construction | 2010 |
| Blade Scaffolding Limited | Construction | 2013 |
| Blade Sky Safe Ltd | Construction | 2023 |
| Blade Storage Ltd | Real estate | 2025 |
| Blade Traffic Management Limited | Transport & logistics | 2012 |
| Blades Fades Ltd | Other services | 2026 |
| Blaise Rose DEX Limited | Construction | 2025 |
| Blake Design Group Ltd | Financial services | 2024 |
| Blank Label Ltd | Wholesale & retail | 2025 |
| Blast IT Away Ltd | Construction | 2018 |
| BLC Holdings Limited | Financial services | 2019 |
| Blend UR Spice Ltd | Manufacturing | 2021 |
| Blend&Buy Limited | Wholesale & retail | 2016 |
| Blendit Shakes Ltd | Hospitality | 2026 |
| Blessed Antoine Ltd | Wholesale & retail | 2025 |
| Blessed Autosport Limited | Wholesale & retail | 2024 |
| Blessed Christopher Wharton Catholic Academy Trust | Education | 2014 |
| Blessings Day Care & Nursery Ltd | Health & social care | 2018 |
| Bleu Properties Ltd | Real estate | 2004 |
| Bleu Properties Two Limited | Real estate | 2011 |
| Blincht DIG Ltd | Construction | 2026 |
| Blinds 4 Decor Ltd | Manufacturing | 2019 |
| Blinds Enterprise Ltd | Other services | 2025 |
| Blinds Range Ltd | Manufacturing | 2020 |
| Blinds Vault Ltd | Manufacturing | 2025 |
| Blinds World Direct Ltd | Other services | 2024 |
| Blinds World Ltd | Other services | 2019 |
| Blindsflex UK Limited | Other services | 2020 |
| Bling Art Limited | Wholesale & retail | 2013 |
| Blinkstash Ltd | Information & communication | 2021 |
| Blisbell Ltd | Wholesale & retail | 2025 |
| Blockley Farming Limited | Real estate | 2018 |
| Blockley Holdings Ltd | Professional & scientific | 2018 |
| Blockley Rental Limited | Wholesale & retail | 2014 |
| Bloodbath Ltd | Information & communication | 2018 |
| Bloom Express Limited | Wholesale & retail | 2026 |
| Bloomberry Holdings Limited | Other services | 2016 |
| Bloomin Buds Theatre Company Limited | Arts & recreation | 2017 |
| Blooming Brain Ltd | Wholesale & retail | 2026 |
| Bloomingcreations.X Ltd | Wholesale & retail | 2024 |
| Bloommist Ltd | Wholesale & retail | 2026 |
| Blooms Media Ltd | Professional & scientific | 2019 |
| Blooms of Bradford Limited | Wholesale & retail | 2020 |
| Blooms on Market Street Ltd | Wholesale & retail | 2019 |
| Bloomsbynur Ltd | Wholesale & retail | 2025 |
| Bloomtree Enterprises Limited | Professional & scientific | 2022 |
| Blossom Beauty and Hair Salon Ltd | Other services | 2024 |