| BJJ Success Ltd | Education | 2019 |
| BJR Property Managment Ltd | Real estate | 2025 |
| BJW Ltd | Hospitality | 2018 |
| BL Halesowen Limited | Hospitality | 2021 |
| BL Shirley Limited | Hospitality | 2016 |
| Black & Bluesmith Ltd. | Professional & scientific | 2018 |
| Black Allium Ltd | Hospitality | 2022 |
| Black and Co Managerment Ltd | Real estate | 2019 |
| Black and Gray Holdings Limited | Real estate | 2017 |
| Black and White Premium Barbers Ltd | Other services | 2020 |
| Black Barn Filby Ltd | Hospitality | 2023 |
| Black Bear Construction and Civils Limited | Construction | 2017 |
| Black Cat Close Management Company Limited | Real estate | 2026 |
| Black Cat Inn Ltd | Hospitality | 2020 |
| Black Country Jaguars Limited | Manufacturing | 2020 |
| Black Crow Gaming Ltd | Manufacturing | 2025 |
| Black Dagger Tattoo Ltd | Other services | 2015 |
| Black Dove Developments Ltd | Construction | 2021 |
| Black Dragon Collectables Ltd | Wholesale & retail | 2009 |
| Black Dragon Consulting Limited | Information & communication | 2000 |
| Black FOX Marketing Ltd | Professional & scientific | 2021 |
| Black FOX Web Services Ltd | Professional & scientific | 2026 |
| Black Horse Consulting Limited | Professional & scientific | 2024 |
| Black Kettle (Norfolk) Limited | Professional & scientific | 2011 |
| Black Lightning Europe Limited | Administrative & support | 2019 |
| Black Mountain Productions Limited | Information & communication | 2025 |
| Black Mouse Group Ltd | Wholesale & retail | 2020 |
| Black Nugget Films Ltd | Information & communication | 2026 |
| Black Olive Restaurants Ltd | Hospitality | 2019 |
| Black Orange INV Ltd | Real estate | 1997 |
| Black RAT Projects Limited | Wholesale & retail | 2012 |
| Black River Jamaican Kitchen Limited | Hospitality | 2025 |
| Black Sands Communications Ltd | Professional & scientific | 2022 |
| Black Sheep Limited | Manufacturing | 1982 |
| Black Swan Care Group Limited | Professional & scientific | 2017 |
| Black Swan Homecare Limited | Health & social care | 2025 |
| Black Swan International Limited | Health & social care | 1991 |
| Black Swan Property Group Limited | Real estate | 2018 |
| Black Swan Systems Ltd | Administrative & support | 2009 |
| Black Swan Taxi Ltd | Transport & logistics | 2019 |
| Black Swan Topco Limited | Financial services | 2020 |
| Black Triangle Aviation Ltd | Transport & logistics | 2021 |
| Black Unicorn Properties Limited | Real estate | 2020 |
| Blackberry Property Development Limited | Construction | 2021 |
| Blackberry Services Limited | Hospitality | 2016 |
| Blackbird Retail Holdings Limited | Professional & scientific | 2009 |
| Blackfriars Gate Limited | Real estate | 2013 |
| Blackham Station Cafe Limited | Hospitality | 2024 |
| Blackheath Property Holdings Ltd | Financial services | 2019 |
| Blackhill Construction (Norfolk) Ltd | Construction | 2020 |
| Blackmoore Consulting Limited | Professional & scientific | 2009 |
| Blackshore Clothing Ltd | Manufacturing | 2025 |
| Blacksmith Productions | | 1993 |
| Blackstone Equity Ltd | Financial services | 2019 |
| Blackstone UK Consulting Limited | Professional & scientific | 2016 |
| Blackthorn Consultancy Services Limited | Professional & scientific | 2005 |
| Blackwell House Clothing Ltd | Manufacturing | 2025 |
| Blade Merchandise Limited | Wholesale & retail | 2017 |
| Bladestorm Limited | Real estate | 2023 |
| Blake Developments (Norfolk) Ltd | Real estate | 2014 |
| Blake Family Property Ltd | Real estate | 2025 |
| Blake Waste Management Ltd | Water & waste | 2025 |
| Blakeleigh (Holdings) Limited | Professional & scientific | 2013 |
| Blakeleigh Assets Ltd | Financial services | 2025 |
| Blakeney Knitwear Company Limited(The) | Extraterritorial | 1958 |
| Blakes Motor Engineers Limited | Administrative & support | 2003 |
| Blakes Self Loading Vehicles Limited | Transport & logistics | 2005 |
| Blandfords & Co Limited | Professional & scientific | 2007 |
| Blank Canvas Productions Ltd | Arts & recreation | 2011 |
| Blankly Ltd | Arts & recreation | 2025 |
| Blaxhall Village Inn Limited | Hospitality | 2011 |
| Blazer Court Management Limited | Real estate | 2009 |
| Blazing Padels Limited | Arts & recreation | 2023 |
| BLE Catering Ltd | Hospitality | 2020 |
| BLE Enterprises Ltd | Financial services | 2020 |
| Bleat Creative Ltd | Professional & scientific | 2023 |
| Blemroy Studios Ltd | Information & communication | 2026 |
| Blend Associates Ltd | Professional & scientific | 2013 |
| Blended People Development Limited | Professional & scientific | 2016 |
| Blengdale Limited | Professional & scientific | 2009 |
| Blenheim Cricket Ltd. | Wholesale & retail | 2016 |
| Blenheim Park Residents Association Limited | Real estate | 1985 |
| Blenheim Place (Norwich) Management Company Limited | Households | 2001 |
| Blenheim Villa Properties Limited | Real estate | 2022 |
| Blessed Hope Religious and Theological Inquiry Center Ltd | Education | 2025 |
| Blessing Beauty Salon Ltd | Other services | 2025 |
| Blessing Lifetime Health Care Ltd | Health & social care | 2015 |
| BLI Consulting Engineers Ltd | Professional & scientific | 2016 |
| BLI Services Ltd | Professional & scientific | 2024 |
| Blind Inspiration Limited | Extraterritorial | 2001 |
| Blind PIG Hospitality Limited | Health & social care | 2026 |
| Blindside Properties Limited | Construction | 2015 |
| Blink Blink Blink Ltd | Information & communication | 2021 |
| Bliss Norwich Ltd | Health & social care | 2016 |
| Bliss Tanning & Beauty Ltd | Other services | 2024 |
| Bliss Tiling Limited | Construction | 2007 |
| Blissful Finds 2024 Limited | Wholesale & retail | 2024 |
| Blissful Locations Ltd | Hospitality | 2024 |
| BLJ Productions Ltd | Information & communication | 2014 |
| Blkbar Ltd | Wholesale & retail | 2026 |