| Biopharm Technical Solutions Limited | Professional & scientific | 2000 |
| Birmingham City International College Ltd | Education | 2010 |
| BJ Powell Properties Ltd | Real estate | 2025 |
| BJ Powell Racing Ltd | Arts & recreation | 2014 |
| BJ Robinson Developments Ltd | Construction | 2019 |
| BJ Robinson Limited | Construction | 2014 |
| Black Sheep Pro Ltd | Professional & scientific | 2019 |
| Black Star Riders Limited | Arts & recreation | 2019 |
| Black Wire Music Limited | Arts & recreation | 2013 |
| Blackrdp Ltd | Wholesale & retail | 2026 |
| Blackrock Electrical Ltd | Construction | 2015 |
| Blackwood FM Ltd | Administrative & support | 2022 |
| Blank White Page Limited | Professional & scientific | 2015 |
| Blazeone Limited | Information & communication | 2022 |
| Blearred London Ltd | Arts & recreation | 2017 |
| Bleed Ltd | Arts & recreation | 2020 |
| Blends & Burgers Ltd | Hospitality | 2023 |
| Blondemoney Ltd | Information & communication | 2020 |
| Bloombox Media Limited | Professional & scientific | 2024 |
| Bloomers Bespoke Catering Ltd | Hospitality | 2021 |
| Blue Door Content Limited | Professional & scientific | 2025 |
| Blue Fingertips Ltd | Wholesale & retail | 2026 |
| Bluku Music Limited | Arts & recreation | 2018 |
| Blukuwear Limited | Wholesale & retail | 2018 |
| Bluskye Integrated Consult Ltd | Professional & scientific | 2024 |
| BM Digital Media Limited | Information & communication | 2023 |
| Boarding in UK Ltd | Education | 2019 |
| Boardman, Hawkins & Osborne LLP | | 2015 |
| Boastful Ltd | Manufacturing | 2024 |
| Bognor Braces Limited | Real estate | 2018 |
| Bojen Electrical Limited | Construction | 2005 |
| Bolton Mews Management Limited | Real estate | 2024 |
| BON Record Limited | Professional & scientific | 2021 |
| Bonar Construction Limited | | 1993 |
| Bondchen Ltd | Wholesale & retail | 2021 |
| Bonema Property Limited | Construction | 2023 |
| Boogooyamma Limited | Arts & recreation | 1996 |
| Booway Limited | Wholesale & retail | 2025 |
| BOR Hull Limited | Other services | 2023 |
| Borders Framing Limited | Professional & scientific | 2006 |
| Born Again Concerts Limited | Arts & recreation | 2018 |
| Borodino Limited | Professional & scientific | 2009 |
| Botley Road Sushi Ltd | Wholesale & retail | 2024 |
| Boulevard Brasseries Limited | Hospitality | 1993 |
| Bounce Biomedical Limited | Professional & scientific | 2008 |
| Bounce-Coaching Ltd. | Education | 2018 |
| Bowman International Limited | Manufacturing | 1992 |
| Boxed UP Events Limited | Administrative & support | 2016 |
| BPK Distributions Ltd | Wholesale & retail | 2026 |
| Bpms (Oxford) Limited | Construction | 2025 |
| BR Design Ltd | Construction | 2019 |
| Brad Ellis Ltd | Arts & recreation | 2021 |
| Brana Ltd | Hospitality | 2022 |
| Brave Brewing Company Limited | Manufacturing | 2025 |
| Brazilians Partners Dotcom Limited | Professional & scientific | 2024 |
| Breakaway Tennis Ltd | Other services | 2023 |
| Breakspear Metal & Scrap Ltd | Water & waste | 2024 |
| Brew Tower Condominium Limited | Real estate | 2024 |
| Brian O'Rourke Bloodstock Limited | Arts & recreation | 2014 |
| Brick and Urban Architecture Ltd | Professional & scientific | 2024 |
| Briggs Associates Property Services Limited | Real estate | 2022 |
| Briggs Plumbing & Heating Services Limited | Construction | 2019 |
| Bright Contracting Solutions Ltd | Other services | 2025 |
| Bright Sparks Events Limited | Education | 2011 |
| Bright Sparks Science C.I.C. | Education | 2011 |
| Brighton Car Key Services Limited | Other services | 2024 |
| Brilliant in Excellence (UK) Limited | Arts & recreation | 2016 |
| Briony Geekie Limited | Health & social care | 2020 |
| Briscoe Advisory Ltd | Professional & scientific | 2023 |
| Britannica Homes Ltd | Financial services | 2023 |
| British Honey Importers & Packers Association Limited | Other services | 1989 |
| Brkd Group Limited | Other services | 2024 |
| Brook House 48 Limited | Real estate | 2025 |
| Brook View (Abingdon) Management Company Limited | Real estate | 2014 |
| Brooke Real Estate Limited | Real estate | 2020 |
| Brooke Williams Transport Limited | Transport & logistics | 2004 |
| Brookmead Services Limited | Other services | 2026 |
| Brooks Alexander Limited | Real estate | 2011 |
| Brookwood Property Services Ltd | Real estate | 2002 |
| Brosba Ltd | Health & social care | 2025 |
| Browns Classics LLP | | 2018 |
| Browns Traditional Butchers Ltd | Wholesale & retail | 2026 |
| Brunstad Christian Church Didcot | Other services | 2008 |
| BSA Heritage Limited | Other services | 2011 |
| Bsdr 20111 Limited | Financial services | 2011 |
| BSG International Ltd | Professional & scientific | 2020 |
| Bubbles Cleaning Abingdon Limited | Administrative & support | 2016 |
| Bubs Barbers Limited | Other services | 2023 |
| Buckingham Court (Bicester) Management Company Limited | Households | 2005 |
| Builthealth Limited | Health & social care | 2025 |
| Bullen Hall Farm Ltd | Real estate | 2019 |
| Burning Throne Limited | Information & communication | 2024 |
| Business by Design Ltd | Administrative & support | 2021 |
| Business Financial Consultants Ltd | Professional & scientific | 2026 |
| Business Optics Solutions Ltd | Administrative & support | 2012 |
| Busom Ltd | Wholesale & retail | 2025 |
| Butler and Hannington Property Renovations Limited | Construction | 2023 |
| Butterflies 8Y8 Limited | Other services | 2024 |
| Buy to Buyer Ltd | Wholesale & retail | 2018 |
| Buzz Campers Ltd | Administrative & support | 2024 |