| Blackbriar Services Limited | Other services | 2009 |
| Blackbush Limited | Professional & scientific | 2026 |
| Blackdog Digital Print Limited | Manufacturing | 2010 |
| Blackdog Print Limited | Manufacturing | 2018 |
| Blackdog Trustees Limited | Administrative & support | 2025 |
| Blackfire Trading Ltd | Financial services | 2023 |
| Blackhorse Events Holdings Limited | Arts & recreation | 2021 |
| Blackline Productions Limited | Information & communication | 2026 |
| Blackport Limited | Construction | 1996 |
| Blackrose Equity Management Ltd | Professional & scientific | 2016 |
| Blackstone Care Homes Ltd | Health & social care | 2026 |
| Blackstone Private Hire Ltd | Transport & logistics | 2022 |
| Blackwatch Limited | Administrative & support | 2026 |
| Blackwood Hamilton Limited | Wholesale & retail | 2021 |
| Blaise Living Ltd | Real estate | 2025 |
| Blakes Services Ltd | Administrative & support | 2025 |
| Blakes Venue Ltd | Hospitality | 2025 |
| Blakeset Limited | Real estate | 2004 |
| Blanue Ltd | Wholesale & retail | 2025 |
| Blaxhairfashioin Ltd | Manufacturing | 2024 |
| Blessed 62 Limited | Real estate | 2026 |
| Blessed Miracles Ltd | Professional & scientific | 2014 |
| Bligh Group Ltd | Administrative & support | 2016 |
| Blindata Limited | Administrative & support | 2010 |
| Blinded Minds Ltd | Wholesale & retail | 2024 |
| Bloc FM Ltd | Administrative & support | 2020 |
| Blocum Ltd | Health & social care | 2015 |
| Blondies Estates Ltd | Real estate | 2025 |
| Bloomfield Inc Ltd | Real estate | 2025 |
| Blooming Gardens Ltd | Administrative & support | 2026 |
| Blossoms Estates Ltd | Real estate | 2019 |
| Blue and Black Limited | Administrative & support | 2019 |
| Blue Beat Ltd | Information & communication | 2011 |
| Blue Beat Records Ltd | Arts & recreation | 2011 |
| Blue Contracts Limited | Administrative & support | 2010 |
| Blue Day Advisory Ltd | Information & communication | 2024 |
| Blue Eyes Angel Ltd | Construction | 2016 |
| Blue Flamingo Entertainments Ltd | Arts & recreation | 2008 |
| Blue Heron Homes Ltd | Real estate | 2024 |
| Blue Investment Services Ltd | Real estate | 2020 |
| Blue Iris Consulting Limited | Professional & scientific | 2016 |
| Blue Jasmin Property Limited | Real estate | 2021 |
| Blue Moon UVC Limited | Wholesale & retail | 2021 |
| Blue Oyster Engineering Ltd | Information & communication | 2023 |
| Blue Sabina Ltd | Professional & scientific | 2023 |
| Blue Shield Advanced Exterior Solutions Ltd | Professional & scientific | 2003 |
| Blue Shield Group Limited | Extraterritorial | 2020 |
| Blue Square Property Holdings Limited | Real estate | 2008 |
| Blue Stone Management Services Limited | Professional & scientific | 2017 |
| Blue Yonder Partnership Ltd | Real estate | 2013 |
| Bluebelle Properties Ltd | Real estate | 2021 |
| Bluebird Software Limited | Information & communication | 2009 |
| Bluebrickz Ltd | Wholesale & retail | 2018 |
| Bluecroft - IPE Jubilee Limited | Real estate | 2016 |
| Bluego Ltd | Administrative & support | 2022 |
| Bluemont Developments (Newton Road) Limited | Construction | 2021 |
| Blueprint Electrical Ltd | Construction | 2022 |
| Bluerock Housing CIC | Hospitality | 2026 |
| Bluesky Construction Services Ltd | Construction | 2025 |
| Blueway Capital Ltd | Real estate | 2022 |
| BM Bar and Grill Limited | Hospitality | 2024 |
| BM Core Ltd | Real estate | 2019 |
| Bmal Ltd | Real estate | 2021 |
| BME Solutions Limited | Information & communication | 2003 |
| BMG Protocol Limited | Information & communication | 2010 |
| BMS Consulting Ltd | Health & social care | 2024 |
| Bmsw Limited | Administrative & support | 2011 |
| BMV Alliance Ltd | Wholesale & retail | 2021 |
| BNA Housing CIC | Health & social care | 2024 |
| BNC Foods Limited | Hospitality | 2016 |
| Boacle Ltd | Information & communication | 2024 |
| Board Perspectives Ltd | Professional & scientific | 2024 |
| Boardrite Properties Limited | Construction | 1997 |
| Boardwalk Associates Limited | Health & social care | 2006 |
| Bobby J Ltd | Wholesale & retail | 2023 |
| Bobby J Properties Ltd | Real estate | 2024 |
| Boci Construction Ltd | Construction | 2024 |
| Bodies and Balance PT Ltd | Arts & recreation | 2024 |
| Bodmin Barbers Ltd | Other services | 2021 |
| Bodpair Limited | Information & communication | 2014 |
| Body by ME Pilates Ltd | Arts & recreation | 2025 |
| Bodyhaq Ltd | Health & social care | 2025 |
| Bodylogics Colindale Ltd | Health & social care | 2025 |
| Bodylogics Partners Ltd | Health & social care | 2024 |
| Bodylogics Sports Therapy Clinic Ltd | Health & social care | 2018 |
| Bodylogics Whetstone Ltd | Health & social care | 2025 |
| Bodylogics Winchmore Hill Ltd | Health & social care | 2025 |
| Bodywell Group Ltd | Wholesale & retail | 2023 |
| Boham Aerospace Limited | Professional & scientific | 2018 |
| Boilers and Flow Ltd | Construction | 2025 |
| Boilers Correct Limited | Construction | 2025 |
| Bolfar Limited | Health & social care | 2018 |
| Bolingbroke Management Co. Ltd | Households | 2016 |
| Bon-Phynn Limited | Administrative & support | 2017 |
| Bond Glow Limited | Health & social care | 2006 |
| Bondcent Limited | Health & social care | 2009 |
| Bonner Business Development Ltd | Administrative & support | 2015 |
| Bonneyhome Limited | Professional & scientific | 1994 |
| Bonnycroft Limited | Real estate | 2002 |
| Bonta' Italia Ltd | Wholesale & retail | 2002 |