| Badon Hill Technologies Ltd | Information & communication | 2022 |
| Bahar Barbers Ltd | Other services | 2024 |
| Bahrem Ltd | Wholesale & retail | 2026 |
| Bailey Commercial Consulting Limited | Professional & scientific | 2012 |
| Baird Medcomms Ltd | Professional & scientific | 2024 |
| Bakehouse Lane (Marcham) Management Company Limited | Households | 2016 |
| Balkan Haulage Ltd | Transport & logistics | 2019 |
| Balkan Housing Ltd | Real estate | 2025 |
| Ball & Co Decorating Ltd | Construction | 2024 |
| Ballerkit Ltd | Wholesale & retail | 2025 |
| Balloontastic Limited | Arts & recreation | 2002 |
| Baltic Kitchen Ltd | Information & communication | 2021 |
| Balyan Dijital Urun Servisleri Ltd | Wholesale & retail | 2025 |
| Bamboo Culture Limited | Professional & scientific | 2020 |
| Banbury Water Softeners Ltd. | Manufacturing | 2003 |
| Banning Investments Limited | Health & social care | 2009 |
| Bannister Homes Limited | Construction | 2025 |
| Barber Vehicle Services Limited | Wholesale & retail | 2002 |
| Barileze Cleaning Services Ltd | Administrative & support | 2025 |
| Bark + Bubbles UK Limited | Transport & logistics | 2026 |
| Barker & Broad Ltd | Financial services | 2003 |
| Barn 2011 (Property) Limited | Financial services | 2011 |
| Barry Graham Product Management Limited | Information & communication | 2008 |
| Baseline Business Consulting Limited | Professional & scientific | 2026 |
| Basildon Chemical Co. Limited | Manufacturing | 1971 |
| Bassen Ltd | Wholesale & retail | 2018 |
| Bastiwin Solutions Limited | Other services | 2025 |
| Batesco Ltd | Administrative & support | 2025 |
| Battle & Mack Trading Limited | Wholesale & retail | 2026 |
| BAU Nova Properties Ltd | Real estate | 2024 |
| Baudelaire Dental Clinic Ltd | Health & social care | 2023 |
| Baudelaire Swindon Limited | Health & social care | 2026 |
| Baxter Young Orthotics Ltd | Health & social care | 2021 |
| Bay House (Looe) Limited | Real estate | 2024 |
| Bayard Estates Limited | Professional & scientific | 1991 |
| Baysto Entertainment LLP | | 2017 |
| Bayworth Limited | Real estate | 1997 |
| BAZ1 Ltd | Other services | 2023 |
| BBC Haulage Ltd | Transport & logistics | 2025 |
| BC Properties (South) Limited | Construction | 2022 |
| Bcjd Properties Ltd | Real estate | 2021 |
| BD Thoroughbreds Ltd | Agriculture & fishing | 2026 |
| BDC Healthcare & Education Ltd | Health & social care | 2017 |
| BE Ambient Limited | Wholesale & retail | 2026 |
| BE Brave BE Bold Ltd | Professional & scientific | 2024 |
| BE Solutions Limited | Professional & scientific | 2015 |
| Beacon Financial Services Limited | Financial services | 2002 |
| Beauty Craze Commerce Limited | Administrative & support | 2019 |
| Beazfx Ltd | Financial services | 2025 |
| Beclean Oxford Limited | Administrative & support | 2017 |
| BEE Health and Fitness Ltd | Other services | 2021 |
| BEE Homes & Properties Ltd | Real estate | 2025 |
| Beechwood Electrical Contracting (Hagbourne) Limited | Construction | 1999 |
| Beema Solutions Ltd | Information & communication | 2026 |
| Beertapp Limited | Information & communication | 2025 |
| Beesting and Stone Limited | Manufacturing | 2011 |
| Beezy Systems Ltd | Wholesale & retail | 2020 |
| Begeti Limited | Information & communication | 2021 |
| Beishuang Tongxindao Tongxianghui UK Ltd | Other services | 2019 |
| Bella Napoli (Abingdon) Limited | Hospitality | 2015 |
| BEN Elcock Farriers Limited | Other services | 2009 |
| BEN Jones Racing Limited | Arts & recreation | 2024 |
| BEN Kelsey Ltd | Construction | 2021 |
| BEN Lay's Free Range Ltd | Agriculture & fishing | 2009 |
| Bendel Consulting Ltd | Real estate | 2018 |
| Benedykt Building Ltd | Construction | 2026 |
| Bennett Building Services (Minster Lovell) Ltd | Construction | 2014 |
| Bennett-Lacey Limited | Information & communication | 2012 |
| Berks and Bucks Football Association Limited | Arts & recreation | 2000 |
| Bermuda Bloodstock Limited | Agriculture & fishing | 2021 |
| Berry Consultants LLP | | 2014 |
| Beskar AI Ltd | Professional & scientific | 2024 |
| Bespoke Betsy & Co Ltd | Hospitality | 2023 |
| Besselsleigh Management Company Limited | Households | 1998 |
| Best in Horticulture Limited | Education | 2015 |
| Best in Horticulture NON Active Ltd | Education | 2011 |
| Betweenclock Ltd | Information & communication | 2023 |
| Beurre Noisette Ltd | Hospitality | 2021 |
| BGR Property Services Ltd | Construction | 2024 |
| BHR Farrier Limited | Other services | 2015 |
| BI22 I.T Consultancy Ltd | Information & communication | 2016 |
| Bice Investments Ltd | Financial services | 2022 |
| Bickerton Limited | Professional & scientific | 1988 |
| Bidworker Limited | Information & communication | 2003 |
| Biesterfeld Petroplas Limited | Wholesale & retail | 2002 |
| Big Brain Global Limited | Wholesale & retail | 2024 |
| Big Game Hunters Limited | Manufacturing | 2020 |
| Big Ginger TOM Music Limited | Arts & recreation | 2017 |
| Big Naia LLP | | 2025 |
| Big Scary Monsters Recording Company Limited | Information & communication | 2015 |
| Bigbox (London) Ltd | Arts & recreation | 2013 |
| Biggles Handyman Limited | Construction | 2004 |
| Bigmouthentertainment Limited | Information & communication | 2009 |
| Biletapp Ltd | Information & communication | 2024 |
| Bilgehan Tekstil Ltd | Wholesale & retail | 2025 |
| Bilhos Online Services Ltd | Wholesale & retail | 2021 |
| Billiworx Ltd | Administrative & support | 2024 |
| Bilo AGA Ltd | Other services | 2019 |
| Bind Body & Mind Ltd | Arts & recreation | 2026 |
| Bio-Techne Ltd | Wholesale & retail | 1990 |