| Big FAT Links Limited | Information & communication | 2018 |
| Big Presence Ltd | Professional & scientific | 2021 |
| BIKE9 Ltd | Wholesale & retail | 2022 |
| Billy Catering Co Ltd | Hospitality | 2025 |
| Bimbax Ltd | Construction | 2019 |
| Binbusters of Cheshire Limited | Administrative & support | 2020 |
| Biology Plus Limited | Education | 2026 |
| Biome Fit Limited | Health & social care | 2021 |
| Birbia Sports Limited | Wholesale & retail | 2025 |
| Bird Rock Property Limited | Real estate | 2023 |
| Birdi Dental Limited | Health & social care | 2018 |
| Birdsong Spear Consultancy Ltd | Professional & scientific | 2026 |
| Birkenhead Smile Centre Ltd | Health & social care | 2026 |
| Birmingham Prostate Specialists LLP | | 2025 |
| Biswas EYE Care Limited | Health & social care | 2012 |
| Bitsco Ltd | Information & communication | 2021 |
| BJH Designs Limited | Professional & scientific | 2021 |
| BKM Exports Limited | Wholesale & retail | 2023 |
| BKM Marketing Limited | Extraterritorial | 2016 |
| BL Realisations 2024 Limited | Professional & scientific | 2021 |
| Black Adder BNG Ltd | Professional & scientific | 2024 |
| Black Cat HR Software Consultancy Ltd | Professional & scientific | 2022 |
| Black Knight Security Limited | Real estate | 1998 |
| Black Sand Medical Limited | Health & social care | 2024 |
| Blackbuck Capital Limited | Professional & scientific | 2009 |
| Blackden Estates Limited | Administrative & support | 2019 |
| Blackden Walk 1962 Limited | Extraterritorial | 2014 |
| Blackford ASH Dogs Limited | Agriculture & fishing | 2017 |
| Blackpool Road (Kirkham) Management Company Limited | Households | 2021 |
| Blakenham Finance Limited | Financial services | 1994 |
| Blantyre Developments Limited | Professional & scientific | 1999 |
| BLB Freight Limited | Financial services | 2024 |
| Blessed Caring Community Interest Company | Health & social care | 2023 |
| Blessedcaringpartnership Ltd | Administrative & support | 2022 |
| BLH Hotel Management Ltd | Professional & scientific | 2018 |
| BLH Management Services LLP | | 2016 |
| BLJ Holdings Limited | Financial services | 2020 |
| Block Teknology Ltd | Information & communication | 2023 |
| Blockexit Limited | Real estate | 1999 |
| Blockrocket Limited | Information & communication | 2018 |
| Bloem Direct Limited | Wholesale & retail | 2021 |
| Bloomea Solution Ltd | Wholesale & retail | 2025 |
| Blrv Ltd | Financial services | 2023 |
| Blue Angel Construction Limited | Construction | 2019 |
| Blue IVY Property Developments Ltd | Real estate | 2022 |
| Blue River Wealth Management Limited | Professional & scientific | 2008 |
| Blue Rivers Asset Management Limited | Financial services | 2023 |
| Blue Star Grocery Ltd | Wholesale & retail | 2026 |
| Blueberry Medical Limited | Health & social care | 2019 |
| Bluechip Aviation Consulting Limited | Administrative & support | 2006 |
| Bluesoc Limited | Information & communication | 2020 |
| Blush Aerial Fitness Limited | Health & social care | 2019 |
| Blush Dance Kids Ltd | Arts & recreation | 2025 |
| Blush Dance Limited | Arts & recreation | 2012 |
| Blushing Susie Ltd | Wholesale & retail | 2021 |
| Bmbm Ltd | Real estate | 2023 |
| Bmck Projects Limited | Professional & scientific | 2024 |
| BMR Maintenance Limited | Construction | 2014 |
| Boardman Wills Limited | Professional & scientific | 2026 |
| Bodhi Wellbeing Rooms Ltd | Health & social care | 2025 |
| Body Smart Coaching Ltd | Arts & recreation | 2020 |
| Bodyhubcore Limited | Arts & recreation | 2022 |
| Bodylines Holdings Ltd | Financial services | 2025 |
| Bodylines Limited | Wholesale & retail | 2000 |
| Bohdi Legacy Ltd | Information & communication | 2022 |
| Bollin Construction Limited | Construction | 2019 |
| Bollin Data Services Limited | Information & communication | 2016 |
| Bollin Logistics Ltd | Transport & logistics | 2024 |
| Bollin Nominees Limited | Financial services | 2001 |
| Bollindene Limited | Households | 2000 |
| Bolton Community Practice C.I.C. | Health & social care | 2011 |
| Bolton Volunteer Artillery Association Limited(The) | Health & social care | 1886 |
| Bombus Property Investment Limited | Real estate | 2022 |
| Boodles Dental Limited | Health & social care | 2026 |
| Boone Henry Limited | Professional & scientific | 1998 |
| Borup Property Limited | Real estate | 2025 |
| BOS Aerospace Ltd | Manufacturing | 2012 |
| Bosden Close Management Company Limited | Households | 2005 |
| Bosworth Manor (Stoke Golding) Management Company Limited | Households | 2016 |
| Bott and Co EOT Limited | Financial services | 2025 |
| Bott and Co Solicitors Ltd | Professional & scientific | 2013 |
| Boudicca Boutique Limited | Wholesale & retail | 2016 |
| Boutique Financial Limited | Financial services | 2017 |
| Bowdon Cafe Group Ltd | Hospitality | 2020 |
| Bowers Restaurants (Newcastle) Limited | Financial services | 1953 |
| Bowler Medcomms Ltd | Administrative & support | 2016 |
| BOX21 Fitness Ltd | Arts & recreation | 2021 |
| Boxworks Storage Ltd | Transport & logistics | 2025 |
| Boyco UK (Holdings) Ltd | Administrative & support | 2014 |
| BR Surveying Services Ltd | Professional & scientific | 2015 |
| Brabner FOX Limited | Administrative & support | 2025 |
| Bracey Overseas Ltd | Wholesale & retail | 2012 |
| Bracken Education Consultants Ltd | Education | 2014 |
| Bracken Ground Limited | Hospitality | 2025 |
| Brackenboro Medical Company Limited | Real estate | 2001 |
| Braddy-Green Services Ltd | Health & social care | 2025 |
| Bradford Curry House Limited | Hospitality | 2019 |
| Bragg FIC Limited | Financial services | 2025 |
| Brain Health Consultancy Ltd | Health & social care | 2023 |
| Bramall Investment Company Limited | Real estate | 2003 |