| B.W. Male & Sons Limited | Real estate | 1974 |
| BAF Property Management Ltd | Real estate | 2023 |
| Baffin Technology Systems Limited | Wholesale & retail | 2016 |
| Baileys Bales Ltd | Agriculture & fishing | 2024 |
| Baker Thompson (Daventry) Limited | Manufacturing | 1994 |
| Bamboo Fresh Restaurants UK Ltd | Hospitality | 2022 |
| Bantock Close Flats Management Limited | Households | 1995 |
| Barberia Group Ltd | Other services | 2019 |
| Bare Basics International Limited | Wholesale & retail | 2021 |
| Barnard & Barnard Ltd | Real estate | 2015 |
| BARNUS06 Ltd | Extraterritorial | 2018 |
| Baroque Acoustics LAB (UK) Limited | Professional & scientific | 2011 |
| Barronco Engineering Solutions Ltd | Professional & scientific | 2023 |
| Barton Psychology Ltd | Health & social care | 2025 |
| Bartora Limited | Information & communication | 2007 |
| Basy Trans Ltd | Transport & logistics | 2011 |
| Bates Composites Ltd | Manufacturing | 2018 |
| Bati Limited | Other services | 2018 |
| Battle Barn Ltd | Information & communication | 2025 |
| Battle in on Ltd | Professional & scientific | 2023 |
| Battlefield Hobbies Limited | Wholesale & retail | 2015 |
| BBM Sport Ltd | Arts & recreation | 2024 |
| BC Ceilings & Partitions Limited | Construction | 2025 |
| BC Extensions Limited | Construction | 2011 |
| BC Health Consulting Ltd | Wholesale & retail | 2022 |
| BDB Itam Consulting Limited | Information & communication | 2017 |
| BDS Design Studio Ltd | Professional & scientific | 2020 |
| BE Curious Tutoring Ltd | Education | 2023 |
| BE Well Wellness Centre Ltd | Health & social care | 2025 |
| Be-Mar Ltd | Manufacturing | 2023 |
| Bear & Bell Investments Ltd | Financial services | 2025 |
| Beckthorne Limited | Information & communication | 2016 |
| Beech Property Investments Limited | Real estate | 2002 |
| Beff and ROB Enterprises Ltd | Health & social care | 2013 |
| Beglow Limited | Professional & scientific | 2016 |
| Bellus SFM Beauty Trainings LLP | | 2023 |
| Belmar Technologies Ltd | Water & waste | 2012 |
| BEN Smith Pubs Ltd | Hospitality | 2025 |
| Benefit Savings Company Ltd | Professional & scientific | 2009 |
| Benefits Plus Ltd | Professional & scientific | 2024 |
| Benzib Ltd | Transport & logistics | 2017 |
| Beowulf Diagnostics Limited | Information & communication | 2026 |
| Bernard RG Ltd | Transport & logistics | 2023 |
| Berryfields Farms Limited | Agriculture & fishing | 1963 |
| Berrystock Feeds Limited | Financial services | 2012 |
| Bespoke Handmade Creations Limited | Wholesale & retail | 2026 |
| Best Before It's Gone Ltd. | Wholesale & retail | 2004 |
| Best Garden Investment Limited | Extraterritorial | 2010 |
| Betemy Ltd | Transport & logistics | 2020 |
| Beverley Polo Investment and Development Co., Ltd | Professional & scientific | 2011 |
| BGK Financial Planning Ltd | Financial services | 2019 |
| BHB Electrical Limited | Construction | 2025 |
| Biaius Ltd | Transport & logistics | 2025 |
| Biavoi Limited | Transport & logistics | 2024 |
| Bidco 8787 Limited | Professional & scientific | 2019 |
| Big Bear Kustoms Ltd | Wholesale & retail | 2016 |
| Big Fulfilment Limited | Transport & logistics | 2024 |
| Big Safety Ltd | Wholesale & retail | 2021 |
| Biko Engineering UK Limited | Wholesale & retail | 2016 |
| Bioblue Ltd | Wholesale & retail | 2025 |
| Bioblue UN Limited | Wholesale & retail | 2026 |
| Biolab Automation Designs Ltd | Professional & scientific | 2021 |
| Biologica Solutions Ltd | Wholesale & retail | 2020 |
| Biotech Solutions (UK) Ltd | Wholesale & retail | 2010 |
| Biotherm Co., Ltd | Professional & scientific | 2016 |
| Birchwood Management & Consulting Ltd | Professional & scientific | 2023 |
| Birsanu Land & Property Limited | Real estate | 2020 |
| Bitservices Ltd | Information & communication | 2017 |
| BJ Trans Ltd | Transport & logistics | 2015 |
| Black Bear Group Limited | Professional & scientific | 2005 |
| Black Rose Barber Co. Ltd | Other services | 2020 |
| Black Sheep Transport Ltd | Transport & logistics | 2018 |
| Black Swan Architecture Ltd | Professional & scientific | 2020 |
| Blackbird Psychology Ltd | Health & social care | 2026 |
| Blacksilo Projects Ltd | Information & communication | 2024 |
| Blackthorn Financial Services Ltd | Financial services | 2021 |
| Blackthorn Wills & Estate Planning Ltd | Professional & scientific | 2024 |
| Blackwing Corporation Ltd | Wholesale & retail | 2026 |
| Blakesley & District Agricultural Show Ltd | Other services | 2011 |
| Blenheim Books Limited | Professional & scientific | 1997 |
| Blooming Trade Co., Limited | Professional & scientific | 2020 |
| Blu-Ray Technology Co., Ltd | Professional & scientific | 2022 |
| Blue # Studio Ltd | Information & communication | 2021 |
| Blue EYE International Limited | Wholesale & retail | 2010 |
| Bluebell Technology Ltd | Manufacturing | 2005 |
| Bluefair Limited | Other services | 2012 |
| BMK Consulting Services Ltd | Other services | 2023 |
| Board Rapport Ltd | Information & communication | 2024 |
| Bobify AI Ltd | Information & communication | 2025 |
| Boddington Barn Developments Limited | Real estate | 2016 |
| Body Equilibrium Ltd | Administrative & support | 2016 |
| Body Shop Solutions Limited | Wholesale & retail | 2004 |
| Bodyguard Daventry Ltd | Other services | 2019 |
| Bodyshop Solutions Holdings Limited | Wholesale & retail | 2013 |
| Bokman Ltd | Professional & scientific | 2021 |
| Boleyn Properties Limited | Professional & scientific | 2004 |
| Boman Cove Ltd | Other services | 2026 |
| Bondwolfe Holdings Limited | Construction | 1991 |
| Boost Hunters Engineering Ltd | Professional & scientific | 2021 |
| Boundless Intercontinental Group Co., Limited | Extraterritorial | 2013 |