| BG Commercial Cleaning Ltd | Administrative & support | 2025 |
| BG Creations Ltd | Wholesale & retail | 2023 |
| BG Leisure Group Ltd | Hospitality | 2023 |
| Bgrs Global UK Limited | Administrative & support | 1992 |
| BGS Contracting Ltd | Construction | 2018 |
| BH RTM Company Ltd | Households | 2024 |
| Bhandilam Ltd | Information & communication | 2025 |
| Bhartiya Consultancy Services Limited | Information & communication | 2015 |
| Bhcs Limited | Real estate | 1999 |
| Bhcs Property Group Limited | Financial services | 2017 |
| Bher Limited | Real estate | 2024 |
| BHP Motors Swindon Ltd | Wholesale & retail | 2026 |
| BHP Selfdrive Ltd | Administrative & support | 2023 |
| BI Trendz Limited | Information & communication | 2015 |
| Bianca Poara Ltd | Manufacturing | 2024 |
| Biancardi Legal Services Ltd | Professional & scientific | 2022 |
| BIB Quality Care Limited | Health & social care | 2026 |
| Bible Society Resources Limited | Information & communication | 2005 |
| Bibzenterprises Ltd | Wholesale & retail | 2025 |
| Bifrosha Ltd | Wholesale & retail | 2025 |
| Big Barn Media Group Limited | Information & communication | 2025 |
| Big Battles Ltd | Manufacturing | 2019 |
| Big C Kitchen Ltd | Hospitality | 2026 |
| Big House Care Limited | Health & social care | 2022 |
| Big LOZ Official Ltd | Arts & recreation | 2020 |
| Big Red Kite Ltd | Manufacturing | 2002 |
| Big Tech Careers Ltd | Information & communication | 2024 |
| Big Yellow Marketing Communications Ltd | Information & communication | 2014 |
| Bigbellyjerkman Ltd | Hospitality | 2025 |
| Bigdatasoft Limited | Information & communication | 2018 |
| Bigshop Ltd | Wholesale & retail | 2025 |
| Bigtime Global Ltd | Information & communication | 2016 |
| Bigtime Radio, TV & Entertainment Group Ltd | Arts & recreation | 2016 |
| Bigtimeamp Ltd | Information & communication | 2025 |
| Bike PIT T/A Moto Cave Limited | Wholesale & retail | 2020 |
| Bike Treads Motorcycle Centre Ltd | Wholesale & retail | 2026 |
| Biker Emporium Ltd | Wholesale & retail | 2015 |
| Bikers Stop Ltd | Information & communication | 2026 |
| Bilbster Wind Farm Limited | Energy | 2006 |
| Billet Precision Ltd | Manufacturing | 2024 |
| BIM Consultancy Services Ltd | Information & communication | 2024 |
| BIM Fusion Limited | Professional & scientific | 2020 |
| Bims Consulting Ltd | Information & communication | 2024 |
| BIN BAG Productions Limited | Information & communication | 2024 |
| BINARY10 Ltd | Information & communication | 2018 |
| Bingham Rose Communications Limited | Administrative & support | 2013 |
| BIO Systems Assure Limited | Manufacturing | 2017 |
| Bioground Ltd | Administrative & support | 2026 |
| Bios-Footprint Ltd | Financial services | 2020 |
| Biovation Biological Solutions Limited | Wholesale & retail | 2023 |
| Bioviron International Limited | Manufacturing | 2007 |
| Biplob Restaurant Ltd | Hospitality | 2026 |
| Biplob Services Limited | Hospitality | 1993 |
| BIR Consultancy Limited | Professional & scientific | 2025 |
| Birakos Ltd | Health & social care | 2023 |
| Birch Construction Services Limited | Construction | 2024 |
| Bircherproperties Limited | Real estate | 2024 |
| Birchstone Construction Limited | Construction | 2025 |
| Birmingham Business Park Management Limited | Real estate | 1988 |
| Bishop Scenic Arts Ltd | Arts & recreation | 2026 |
| Bite Factory Ltd | Hospitality | 2025 |
| Bites & Banquets Ltd | Hospitality | 2026 |
| Bites 4 ALL Ltd | Construction | 2026 |
| Bivo Travel Ltd | Transport & logistics | 2019 |
| Bizcorp Group Ltd | Information & communication | 2019 |
| Bizvid Ltd | Real estate | 2022 |
| BJD Power Ltd | Construction | 2024 |
| BJM Engineering Limited | Professional & scientific | 2022 |
| BK Private Ltd | Hospitality | 2024 |
| BKI Projects Limited | Construction | 2017 |
| BKM Swindon Construction Ltd | Construction | 2025 |
| Black and White Management Limited | Real estate | 2011 |
| Black Arrow Space Technologies Ltd | Manufacturing | 2017 |
| Black Barns Management Ltd | Households | 2022 |
| Black Cactus Media Ltd | Information & communication | 2021 |
| Black Cat Archery Ltd | Arts & recreation | 2008 |
| Black Cats Developer Limited | Information & communication | 2018 |
| Black Heart INK LLP | | 2024 |
| Black Horse Joinery Ltd | Manufacturing | 2026 |
| Black N White Events Transport Ltd | Transport & logistics | 2018 |
| Black Oak Brickwork Limited | Construction | 2024 |
| Black Telos Capital Limited | Financial services | 2024 |
| Blackburn Interiors Limited | Construction | 2022 |
| Blackdogpurchasing Ltd | Administrative & support | 2010 |
| Blackford's Turf & Topsoil Limited | Wholesale & retail | 1996 |
| Blacklands Organics Ltd | Agriculture & fishing | 2021 |
| Blackler Railton Limited | Construction | 2003 |
| Blackpool Karate LLP | | 2013 |
| Blackstrad Limited | Wholesale & retail | 2025 |
| Blackwing Networks Ltd | Information & communication | 2024 |
| Blade Design Limited | Professional & scientific | 2004 |
| Blake House RTM Company Ltd | Households | 2020 |
| Blakes IT Consultancy Limited | Information & communication | 2009 |
| Blanco-Noor Limited | Health & social care | 2011 |
| Blank Canvas Consulting Limited | Professional & scientific | 2025 |
| Blazecourt Limited | Construction | 2007 |
| Blazed Store Limited | Wholesale & retail | 2022 |
| BLB Kilminster Beer LLP | | 2011 |
| BLD Betters Limited | Wholesale & retail | 2025 |
| Blenheim Management Company Limited | Households | 2008 |