| Blossom Hill Care Group Ltd | Health & social care | 2025 |
| Blossom Homes Limited | Construction | 2016 |
| Bloxham Holdings Limited | Financial services | 2017 |
| BLU Mount Ltd | Professional & scientific | 2011 |
| Blue Box Products Limited | Wholesale & retail | 2015 |
| Blue Chip Collectibles Limited | Wholesale & retail | 2025 |
| Blue GEM Corporate Services Limited | Real estate | 2013 |
| Blue GEM Holdings Limited | Financial services | 2023 |
| Blue GEM Management Services Limited | Financial services | 2023 |
| Blue Mango Enterprises Limited | Hospitality | 2017 |
| Blue Roman Services Limited | Other services | 2009 |
| Blue Wisdom Software Innovations Limited | Information & communication | 2017 |
| Bluebird Boats Limited | Wholesale & retail | 1998 |
| Blueflame Environmental Ltd | Construction | 2014 |
| Bluehouse Hardwoods Limited | Wholesale & retail | 2005 |
| Blueline Property Group Ltd | Real estate | 2024 |
| Blueprint Acquisitions Limited | Financial services | 2009 |
| Blueprint AV Limited | Wholesale & retail | 2024 |
| Blueprint Design and Build Limited | Construction | 2023 |
| Blueprint Devons Wharf Limited | Construction | 2020 |
| Blueprint Devons Wharf Residential Limited | Real estate | 2023 |
| Blueprint Estate Agents Brentwood Limited | Real estate | 2018 |
| Blueprint Investments (London) Limited | Extraterritorial | 2012 |
| Blueprint Lettings and Management Brentwood Limited | Real estate | 2024 |
| Blueprint Logistics London Limited | Wholesale & retail | 2025 |
| Blueprint Residential Limited | Real estate | 2021 |
| Bluestone Property Limited | Real estate | 2016 |
| Bluestripe Limited | Construction | 1998 |
| Blunreach Properties Limited | Construction | 1998 |
| Blythswood Management Limited | Households | 1989 |
| Bmba Ltd | Administrative & support | 2012 |
| Bmcp Group Ltd | Health & social care | 2022 |
| BME Business Consultant Ltd | Professional & scientific | 2020 |
| BMG Agency Limited | Wholesale & retail | 2003 |
| BMV Auto Expert Ltd | Wholesale & retail | 2025 |
| BNL Digital Solutions Ltd | Information & communication | 2025 |
| BOA Education Ltd | Extraterritorial | 2023 |
| Boardroom Dialogue Group Ltd | Professional & scientific | 2016 |
| Boathouse Events Ltd | Hospitality | 2013 |
| BOB Terry Haulage Limited | Transport & logistics | 2007 |
| Bobbys Girl 2019 Ltd | Wholesale & retail | 2019 |
| Bobby’S Bodywork Ltd | Wholesale & retail | 2024 |
| Bocs Construction Limited | Construction | 2017 |
| Bodywash Bathrooms Limited | Wholesale & retail | 2002 |
| Bohan Capital Limited | Real estate | 2022 |
| Bois Hall Barns Management Limited | Real estate | 2016 |
| Bold and Beautiful Services Ltd | Health & social care | 2025 |
| BOLD+291 Limited | Transport & logistics | 2026 |
| Bolder Product Ltd | Information & communication | 2017 |
| Boleyn Financial Services Ltd | Professional & scientific | 2018 |
| Bolt-On Creative Limited | Professional & scientific | 2015 |
| Bomb Noodle Productions Ltd | Information & communication | 2019 |
| Bonds of Brentwood Limited | Wholesale & retail | 2015 |
| Bonham Properties Limited | Real estate | 1993 |
| Boocar Limited | Wholesale & retail | 2004 |
| Bookenz UK Limited | Wholesale & retail | 2011 |
| Booth Accountants Ltd | Professional & scientific | 2004 |
| Bornso LLP | | 2015 |
| Bosscor Limited | Information & communication | 2025 |
| Bosse Ltd | Hospitality | 2019 |
| Bossie's Ice Creams Ltd | Hospitality | 2023 |
| Botella Imports Ltd | Wholesale & retail | 2016 |
| Bottega Beauty Ltd | Construction | 2019 |
| Bounce Marketing Limited | Information & communication | 2023 |
| Bowcan Ltd | Hospitality | 2022 |
| Bowen Advisory Limited | Professional & scientific | 2026 |
| Bowring Solutions Limited | Financial services | 2025 |
| Box Clothing Limited | Wholesale & retail | 2015 |
| Boxd LDN Ltd | Transport & logistics | 2017 |
| Boyle Group Limited | Other services | 2016 |
| Boyle Highways TM Limited | Education | 2014 |
| Boys Gym Wear Ltd | Wholesale & retail | 2026 |
| BPC Consultants Limited | Information & communication | 2021 |
| BPL Estates Ltd | Real estate | 2011 |
| BPL Property Management Ltd | Real estate | 2012 |
| Braavos Rivers Limited | Construction | 2021 |
| Brac Contracts Limited | Construction | 2006 |
| Bracken House Services Limited | Professional & scientific | 2023 |
| Bracknell Forest Cambium Partnership LLP | | 2020 |
| Brad Rigging Limited | Construction | 2023 |
| Bradley Jones Ltd | Financial services | 2007 |
| Bradshaw Equity Limited | Other services | 2013 |
| Bradshaw Gate Barbers(Leigh) Ltd | Other services | 2019 |
| Bradshaw Luxury Appliances Limited | Wholesale & retail | 2016 |
| Bradstone Construction Limited | Construction | 2025 |
| Bradybunch Design Ltd | Professional & scientific | 2018 |
| Brain Bridge Technology Limited | Information & communication | 2014 |
| Brampton Kids Club Ltd | Education | 2010 |
| Brand NEU Ltd | Wholesale & retail | 2023 |
| Brand Packaging Solutions Limited | Administrative & support | 2009 |
| Brandbox Agency Ltd | Professional & scientific | 2024 |
| Brandlistry Ltd | Wholesale & retail | 2020 |
| Brands House Freehold Ltd | Real estate | 2018 |
| Brandsbox Ltd | Wholesale & retail | 2023 |
| Braqi Property Ltd | Real estate | 2023 |
| Brava Windows and Doors Ltd | Construction | 2012 |
| Brazy Limited | Manufacturing | 2023 |
| BREAK4U Ltd | Hospitality | 2025 |
| Breakout Interiors-Uk Ltd | Wholesale & retail | 2016 |
| Brechin Corporate Consultants Limited | Financial services | 2015 |