| Blackwyne Ltd | Information & communication | 2023 |
| Blade Communications (Leamington Spa) Limited | Professional & scientific | 1994 |
| Blaze Charging Limited | Energy | 2025 |
| Bliss Data Consulting Limited | Information & communication | 2014 |
| Bliss Data Investments Limited | Real estate | 2023 |
| Bloc Software Ltd | Information & communication | 2026 |
| Blockreg Advisors Ltd | Professional & scientific | 2020 |
| Blossom Beauty Room Limited | Other services | 2016 |
| Blossom Belle Ltd | Professional & scientific | 2020 |
| BLU Wingu Ltd | Information & communication | 2014 |
| Blue Computers Limited | Information & communication | 1989 |
| Blue Crystal Capital Limited | Other services | 2026 |
| Blue Dude Limited | Wholesale & retail | 2023 |
| Blue Gemini Consulting Limited | Information & communication | 2015 |
| Blue Kite Recruitment Ltd | Administrative & support | 2016 |
| Blue Peak Consulting Limited | Professional & scientific | 2016 |
| Blue Peak Group Limited | Financial services | 2023 |
| Blue Peak International Payments Ltd | Administrative & support | 2023 |
| Blue Robin Consulting Ltd | Information & communication | 2022 |
| Blue Sea Financial Limited | Professional & scientific | 2011 |
| Blue Thinking Consulting Ltd | Professional & scientific | 2018 |
| Blue Works Consulting Limited | Information & communication | 2015 |
| Bluehoop Marketing Ltd | Administrative & support | 2011 |
| Bluepipe Services Limited | Construction | 2026 |
| Blueprint Fitted Furniture Limited | Manufacturing | 2014 |
| Blueprint Holdings Limited | Financial services | 2017 |
| Bluesky Certification Ltd | Extraterritorial | 2016 |
| Bluesky Test Laboratories Limited | Professional & scientific | 2017 |
| Blush Beauty Reading Ltd | Other services | 2025 |
| BM Beauty & Health Media Limited | Manufacturing | 2026 |
| BM Grande Marques Ltd | Wholesale & retail | 2019 |
| BMF Scaffolding Ltd | Construction | 2025 |
| Bn-Eweka Limited | Financial services | 2016 |
| BNA Plumbing & Heating Ltd | Construction | 2019 |
| BNA Properties Ltd | Real estate | 2019 |
| BOB Fish & Chips Ltd | Hospitality | 2018 |
| BOB Moore Models Limited | Manufacturing | 2003 |
| Boba Bloom Ltd | Hospitality | 2021 |
| Bobs F&C Ltd | Hospitality | 2024 |
| Boce Developments Ltd | Construction | 2021 |
| Body+Art Limited | Arts & recreation | 2026 |
| Boltblue Limited | Real estate | 2017 |
| Bombay Story Group Limited | Hospitality | 2025 |
| Bond Brews Ltd | Manufacturing | 2015 |
| Bond Metaltek Ltd | Wholesale & retail | 2021 |
| Bonham Gate Management Company Limited | Real estate | 2007 |
| Bonham House Management Company Limited | Real estate | 2007 |
| Booked Images Limited | Manufacturing | 2006 |
| Bookkeeping Legends Limited | Professional & scientific | 2026 |
| Boom Pole Media Ltd | Information & communication | 2021 |
| Borer Data Systems Limited | Administrative & support | 1975 |
| Boston Golf TEE Company Limited(The) | Arts & recreation | 1987 |
| Bouleversant Limited | Professional & scientific | 2024 |
| Bouwer & Co Limited | Information & communication | 2022 |
| Bowage Limited | Education | 2009 |
| Bowerbird Property Renovations Ltd | Construction | 2022 |
| Bowman Investments Limited | Real estate | 2018 |
| Box Tart Productions Ltd | Information & communication | 2020 |
| Boxblade Limited | Information & communication | 1997 |
| BP Techserv Ltd | Information & communication | 2015 |
| BPG Property Services Ltd | Real estate | 2024 |
| Bracesoft Ltd | Information & communication | 2025 |
| Bracknell Gymnastics Club | Arts & recreation | 2009 |
| Bracknell Railway Society | Other services | 2004 |
| Brackworth Management Limited | Households | 2022 |
| Bradcutts LLP | | 2024 |
| Braille Forge Ltd | Manufacturing | 2025 |
| Braintree Consulting Ltd. | Information & communication | 2013 |
| Brainvita Ltd | Information & communication | 2018 |
| Brainwave Technologies Ltd | Information & communication | 2025 |
| Brambles and Bloom Ltd | Education | 2025 |
| Bramley Park Developments Limited | Construction | 2017 |
| Brandsentinel.Ai Ltd | Information & communication | 2025 |
| Brannan Carpentry and Building Limited | Manufacturing | 2014 |
| Brass for Africa | Education | 2012 |
| Bravilor Limited | Wholesale & retail | 1978 |
| Braybank Estates Limited | Households | 1998 |
| Braybrook Management Company Limited | Real estate | 2005 |
| Breensco Limited | Extraterritorial | 2022 |
| Brendon Forbes Carpentry Limited | Manufacturing | 2024 |
| Brensim Limited | Health & social care | 2013 |
| Brian Hamblin Limited | Wholesale & retail | 2007 |
| Brian Ives & Co Ltd | Professional & scientific | 2006 |
| Bridges International Coaching Ltd | Other services | 2020 |
| Bridges Property and Investments LLP | | 2018 |
| Bridgewater Intl Ltd | Professional & scientific | 2014 |
| Brighter Living Care Ltd | Health & social care | 2019 |
| Brightfutures Living Ltd | Other services | 2024 |
| Brightstar Research Ltd. | Information & communication | 2023 |
| Brightwell 25 Limited | Hospitality | 2025 |
| Brightwell Healthcare Ltd | Wholesale & retail | 2010 |
| Briklyne Ltd | Real estate | 2025 |
| Bril Group LLP | | 2026 |
| Brilliant Builds UK Ltd | Real estate | 2024 |
| Brisworthy Limited | Agriculture & fishing | 2022 |
| Britchford Export Limited | Health & social care | 1988 |
| British Azerbaijani Community (BAC) CIC | Education | 2024 |
| Brix Engineering Limited | Manufacturing | 2025 |
| Broad House RMC Ltd | Real estate | 2024 |
| Brockenhurst Homes Limited | Construction | 2014 |