| BGC England Ltd | Information & communication | 2018 |
| Biatna Limited | Administrative & support | 2026 |
| Big BAD Wolf Limited | Professional & scientific | 2011 |
| Big Grass Investments Ltd | Financial services | 2024 |
| Bikesentry Ltd | Information & communication | 2025 |
| BIN & Gone Ltd | Water & waste | 2024 |
| Biskit Productions Limited | Arts & recreation | 2020 |
| Black Star Homes Ltd | Construction | 2017 |
| Black Tulip Flowers (UK) Limited | Wholesale & retail | 2023 |
| Blackline Fitness Ltd | Other services | 2023 |
| Blackmoor Wood Limited | Real estate | 2024 |
| Blakedew 833 Limited | Professional & scientific | 2015 |
| Blakemay Ltd | Real estate | 2024 |
| Blakes Luxury Furniture Limited | Manufacturing | 2018 |
| Blend ‘N’ Brew Ltd | Hospitality | 2024 |
| Blindscape Limited | Wholesale & retail | 2005 |
| Blue India Consultancy Limited | Professional & scientific | 2021 |
| Blue Planet Systems Limited | Information & communication | 1997 |
| Blue Storm Media Ltd | Information & communication | 2001 |
| Blue Summerwood Limited | Professional & scientific | 2014 |
| Blueberry Financial Ltd | Financial services | 2008 |
| Bluebrixx UK Limited | Wholesale & retail | 2026 |
| Bluejay Properties Limited | Real estate | 2007 |
| Bluestar Property Management Ltd | Administrative & support | 2020 |
| Bluestar Property Services Ltd | Administrative & support | 2017 |
| BM Management (Langley) LLP | | 2022 |
| BM Property (Langley) Limited | Financial services | 2020 |
| BMH Fire Protection Limited | Professional & scientific | 2020 |
| BNS Construction Ltd | Construction | 2017 |
| BNS Extensions Specialists Limited | Construction | 2023 |
| BNS Holdings Ltd | Financial services | 2025 |
| BNS Homes Limited | Real estate | 2023 |
| BNS Lofts Specialists Limited | Construction | 2023 |
| Boat Race House Limited | Construction | 2016 |
| BOE Trading Ltd | Real estate | 2024 |
| Bold Precision Ltd | Professional & scientific | 2025 |
| Bolder Projects Limited | Administrative & support | 2026 |
| Bondoo Baby Ltd | Manufacturing | 2011 |
| Bonnicut Court Management Company Limited | Real estate | 1994 |
| Border Telecom International Limited | Information & communication | 1993 |
| Borderlinx Limited | Transport & logistics | 2006 |
| Borsodi Ltd | Information & communication | 2016 |
| Both Lifestyle Limited | Professional & scientific | 2025 |
| Boudica Properties Ltd | Real estate | 2019 |
| Bowerbank Corporate Services Limited | Professional & scientific | 2013 |
| BP2015 (HCT) LLP | | 2017 |
| Braaiwood UK Limited | Wholesale & retail | 2017 |
| Bradly Associates Limited | Information & communication | 1988 |
| Brady Searle Consulting Limited | Professional & scientific | 2022 |
| Brady Searle Limited | Real estate | 2019 |
| Brain Jump AI Ltd | Information & communication | 2025 |
| Brainhope Ltd | Health & social care | 2024 |
| Bramham Hall Capital LLP | | 2013 |
| Bramham Properties (HCT) Eight Ltd | Construction | 2021 |
| Brand Box Limited | Professional & scientific | 1986 |
| Brand Equity Asset Management Limited | Professional & scientific | 2015 |
| Brandleaf Strategic Marketing & Communications Ltd | Professional & scientific | 2025 |
| Brandphotoshoots Ltd | Professional & scientific | 2020 |
| Bravo Zulu Property Limited | Real estate | 2017 |
| Breakform Consulting Limited | Professional & scientific | 2025 |
| Breakup & Divorce Global Limited | Other services | 2026 |
| Brent Owens Consulting Ltd | Professional & scientific | 2025 |
| Brewin JV Limited | Real estate | 2014 |
| Brickrash Limited | Wholesale & retail | 2017 |
| Bridge Care Residential Limited | Health & social care | 2000 |
| Bright Crib New Generation Limited | Real estate | 2007 |
| Brightpath Learning Home Ltd | Education | 2025 |
| Brignell Health Limited | Health & social care | 2023 |
| Brill Clean Ltd | Professional & scientific | 2019 |
| Bring OUT the Best Ltd | Professional & scientific | 2015 |
| Brit Anya Ltd | Real estate | 2024 |
| British Champions' Series Limited | Arts & recreation | 2010 |
| Broadham Limited Partnership | | 2005 |
| Brockenhurst Care Services Ltd | Health & social care | 2023 |
| Brohi-Lee Properties Ltd | Real estate | 2026 |
| Brooklong Ltd | Health & social care | 2003 |
| Broomfield Park (Sunningdale) Roads Limited | Professional & scientific | 1989 |
| Brownfield Construction Services Limited | Construction | 2020 |
| Browning Architects Limited | Professional & scientific | 2013 |
| Brymad Data Integrity Ltd | Professional & scientific | 2026 |
| Brymad Limited | Professional & scientific | 2002 |
| Bryn Court Properties Limited | Real estate | 2000 |
| BTL Elite Ltd | Professional & scientific | 2023 |
| Buck Star Managed Services Limited | Information & communication | 2024 |
| Buckhurst Construction Ltd | Construction | 2022 |
| Bukad Ltd | Wholesale & retail | 2024 |
| Bulldog Barbers Ltd | Other services | 2026 |
| Burleigh Healthcare Limited | Health & social care | 2023 |
| Burley Wood Management Company Limited | Other services | 1993 |
| Buxton Developments Ltd. | Construction | 2015 |
| Bydpol Trans Ltd | Transport & logistics | 2018 |
| Bytecare+ Ltd | Other services | 2025 |
| Byway Care Limited | Health & social care | 2003 |
| C.A.S.A Carpentry & Construction Ltd | Construction | 2021 |
| Cadmium Design Consultants Limited | Professional & scientific | 2000 |
| Caip Holdings Limited | Information & communication | 2026 |
| Calder Consulere Limited | Professional & scientific | 2021 |
| Cameron Jones Planning Limited | Professional & scientific | 2016 |
| Camlann Ltd | Information & communication | 2026 |
| Campbell Hooper & Co (2001) Limited | Professional & scientific | 1996 |