| BJR Consultancy Limited | Construction | 2018 |
| BK Risk Consulting Limited | Administrative & support | 2010 |
| Bk-H Technology Services Ltd | Administrative & support | 2020 |
| BKH Lighting Limited | Professional & scientific | 2017 |
| BL Technologies Limited | Professional & scientific | 2019 |
| BL4CKSUN Ltd. | Information & communication | 2016 |
| Blache-Rostron Validation Consultancy Limited | Administrative & support | 2023 |
| Black & White Landscaping Ltd | Administrative & support | 2025 |
| Black Bark Co Ltd | Hospitality | 2018 |
| Black Bear Garage Limited | Wholesale & retail | 1999 |
| Black Bird Theatre Ltd | Arts & recreation | 2026 |
| Black Cat Tech Ltd | Professional & scientific | 2023 |
| Black Dog Solutions Limited | Information & communication | 2014 |
| Black Halo Engineering Ltd | Administrative & support | 2022 |
| Black Magic Tanning UK Limited | Other services | 2014 |
| Blackbird Geotechnical Limited | Administrative & support | 2016 |
| Blackbox Investigations Limited | Transport & logistics | 2024 |
| Blackbrook Car Sales Company Ltd | Wholesale & retail | 2025 |
| Blackbrook Nursery School Limited | Education | 2019 |
| Blackburn CAD Ltd | Administrative & support | 2020 |
| Blackburne Consultancy Ltd | Administrative & support | 2022 |
| Blackdown Engineering Limited | Professional & scientific | 2018 |
| Blackham Engineering Design Limited | Other services | 1998 |
| Blackhouse Lucas Limited | Professional & scientific | 2013 |
| Blackjac Limited | Professional & scientific | 2013 |
| Blackledge Martial Arts Limited | Arts & recreation | 2016 |
| Blackmagic Design Limited | Wholesale & retail | 2008 |
| Blackmonk Engineering Ltd | Administrative & support | 2007 |
| Blackrock Industries Ltd | Wholesale & retail | 2021 |
| Blackshaw Capital Limited | Construction | 2025 |
| Blackthorpe Consulting Limited | Professional & scientific | 2017 |
| Blacktower North West Limited | Real estate | 2020 |
| Blackwoods Valeting Ltd | Administrative & support | 2023 |
| Blagdon Spires Limited | Administrative & support | 2016 |
| Blake Roofing Limited | Construction | 2005 |
| Blameless TM ATC Limited | Manufacturing | 2025 |
| Blanchard Homes Ltd | Real estate | 2024 |
| Blanchfield & Co. Limited | Professional & scientific | 1991 |
| Blaze Modifications Ltd | Wholesale & retail | 2025 |
| Bleng Fell Engineering Limited | Administrative & support | 2012 |
| BLG Food Limited | Hospitality | 2025 |
| Blinke Ltd | Wholesale & retail | 2025 |
| Blinx Solutions Limited | Information & communication | 2014 |
| BLK1 Ltd | Hospitality | 2025 |
| Bloc IT Solutions Ltd | Professional & scientific | 2017 |
| Block & Sharp Holdings Limited | Financial services | 2024 |
| Block Boutique Limited | Wholesale & retail | 2023 |
| Block Support (Legal) Limited | Real estate | 2025 |
| BLOOM3 Ltd | Professional & scientific | 2019 |
| Bloomfield Fashions Ltd | Wholesale & retail | 2023 |
| Blooming Technology Consultants Ltd | Information & communication | 2022 |
| Bloomings Rentals Limited | Hospitality | 2020 |
| Blossom Courtyard Ltd | Hospitality | 2026 |
| Blossom Gate Apartments (Management Company) Limited | Households | 2019 |
| Blossom Lowton Ltd | Hospitality | 2025 |
| Blssmgoods Limited | Wholesale & retail | 2021 |
| Blue Axis Design Ltd | Administrative & support | 2024 |
| Blue Contracting Ltd | Professional & scientific | 2026 |
| Blue Door Studios Ltd | Information & communication | 2019 |
| Blue Dreams Forever Ltd | Wholesale & retail | 2022 |
| Blue Horizon Consulting Limited | Professional & scientific | 2025 |
| Blue JAY Manchester Ltd | Information & communication | 2019 |
| Blue Machinery (Equipment) Limited | Mining & quarrying | 2008 |
| Blue Machinery (Fuchs) Limited | Administrative & support | 2007 |
| Blue Machinery (Group) Limited | Other services | 2003 |
| Blue Machinery (Spares) Limited | Mining & quarrying | 2002 |
| Blue Magnet Investments Ltd | Real estate | 2019 |
| Blue Orange Capital Ltd | Professional & scientific | 2017 |
| Blue Orange Investment Management Ltd | Administrative & support | 2024 |
| Blue Palette Productions Limited | Professional & scientific | 2019 |
| Blue Phoenix Rising Ltd | Professional & scientific | 2023 |
| Blue Prism Group Limited | Information & communication | 2015 |
| Blue Prism Limited | Information & communication | 2001 |
| Blue Projects Site Services Ltd | Construction | 2018 |
| Blue Raccoon Music Limited | Information & communication | 2008 |
| Blue Ribbon Healthcare Group Limited | Financial services | 2020 |
| Blue Ribbon Healthcare Limited | Health & social care | 2016 |
| Blue Sky Mediation Ltd | Administrative & support | 2021 |
| Blue Sky Rocket Limited | Professional & scientific | 2020 |
| Blue Volcano Ltd | Professional & scientific | 2014 |
| Blue Wall Realty Ltd | Real estate | 2022 |
| Blue Whale Eco Limited | Wholesale & retail | 2017 |
| Bluealfie Limited | Hospitality | 2024 |
| Bluebell Fitted Furniture Holdings Limited | Administrative & support | 2023 |
| Bluebell Fitted Furniture Limited | Manufacturing | 2011 |
| Blueberry Properties (R&B) Limited | Construction | 2019 |
| Bluechip Security and Training Ltd | Administrative & support | 2026 |
| Bluegrass Limited | Real estate | 2007 |
| Bluehenco Limited | Administrative & support | 2013 |
| Bluehorizon Mobile Ltd | Information & communication | 2025 |
| Blueprint C.A.D. Limited | Professional & scientific | 2003 |
| Blueshift Solutions Limited | Professional & scientific | 2024 |
| Bluesky Tours Ltd | Administrative & support | 2019 |
| Bluewater Online Ltd | Transport & logistics | 2020 |
| Bluewhitestar Developments Limited | Extraterritorial | 1988 |
| Bluewood Access Limited | Administrative & support | 2025 |
| Bluma Limited | Construction | 2019 |
| BM Auto Body Works Ltd | Wholesale & retail | 2025 |
| Bmap Consultancy Limited | Administrative & support | 2011 |
| BMC Weights Engineering Ltd | Professional & scientific | 2017 |