| Bay Tree Fine Foods Limited | Hospitality | 2012 |
| Bayrock Limited | Information & communication | 1994 |
| Bayrock Projects Limited | Extraterritorial | 2016 |
| Baytree Projects Limited | Information & communication | 2005 |
| BC Electrical & Telecommunications Limited | Construction | 2021 |
| BD Biomedical Consulting Limited | Professional & scientific | 2021 |
| BDS Computers Limited | Administrative & support | 2003 |
| Bear Hotel Events Limited | Hospitality | 2021 |
| Beautiful Property Limited | Real estate | 2017 |
| Beechwood Insights Ltd | Professional & scientific | 2022 |
| Begreener Limited | Professional & scientific | 2003 |
| Belfair Ltd | Information & communication | 2022 |
| Belian.Earth Limited | Professional & scientific | 2024 |
| Bellapaise Lettings Limited | Real estate | 2019 |
| Belmont Property Management Limited | Other services | 1996 |
| BEN Hutchins Ltd | Information & communication | 2015 |
| BEN Smith & Sons(Wantage)Limited | Agriculture & fishing | 1958 |
| BEN Sutton Flooring Limited | Construction | 2019 |
| Benevia Limited | Professional & scientific | 2011 |
| Bentley Gilbert Associates Ltd | Professional & scientific | 2021 |
| Berkshire Roofing Limited | Construction | 2024 |
| Bespoke Ventilation Ltd | Energy | 2011 |
| Beyond Weddings Ltd | Information & communication | 2017 |
| Biaco Power Limited | Professional & scientific | 2020 |
| Biff Bang POW Limited | Information & communication | 2008 |
| Big Red Scaffolding Ltd. | Construction | 2018 |
| Bigger Brighter Bolder Ltd | Other services | 2009 |
| Bigger Brighter Bolder Publishing Ltd | Information & communication | 2018 |
| Billion Automotive Ltd | Wholesale & retail | 2025 |
| Bioholistix Ltd | Wholesale & retail | 2020 |
| Biolacuna Holdco 1 Limited | Financial services | 2021 |
| Biolacuna Holdco 2 Limited | Financial services | 2021 |
| Biolacuna Holdco 4 Ltd | Manufacturing | 2025 |
| Biolacuna Limited | Professional & scientific | 2017 |
| Biolacuna Management Co 1 Ltd | Financial services | 2026 |
| Biotrue Limited | Wholesale & retail | 2025 |
| Biston Healthcare Ltd | Health & social care | 2021 |
| BK Quality Consulting Ltd | Professional & scientific | 2022 |
| Black Barn GRP Ltd | Professional & scientific | 2024 |
| Blake Consultants Limited | Professional & scientific | 2010 |
| Blind Interiors Limited | Other services | 2019 |
| Blindspot Oxfordshire Limited | Real estate | 2016 |
| Block Capital Limited | Information & communication | 2000 |
| Blocksmart Capital Ltd | Financial services | 2022 |
| Blomley Investments Limited | Real estate | 2006 |
| Blossom Bridge Children's Services Ltd | Extraterritorial | 2026 |
| Blue Chip Technologies Ltd | Information & communication | 2019 |
| Blue Flag Pharma Limited | Wholesale & retail | 1997 |
| Blue Milestones Consulting Limited | Administrative & support | 2023 |
| Blue Neon Consulting Ltd | Professional & scientific | 2008 |
| Bluejay's Landscaping Ltd | Administrative & support | 2023 |
| Blueport Limited | Professional & scientific | 2021 |
| Bluestone Planning Ltd | Professional & scientific | 2006 |
| Bluestone Planning Partnership LLP | | 2010 |
| BNL Consulting Ltd | Professional & scientific | 2018 |
| Bogman Pizza Ltd | Hospitality | 2024 |
| Bolton Scaffolding Services Ltd | Construction | 2024 |
| Bookshop Limited | Wholesale & retail | 2022 |
| Bookworld Africa Limited | Information & communication | 2013 |
| Botley Town House Limited | Real estate | 2018 |
| Boxcom Ltd | Information & communication | 2024 |
| Boylan Integral Limited | Administrative & support | 2022 |
| BPJ Construction Limited | Construction | 1999 |
| Brainy Monkey Post Production Limited | Professional & scientific | 2012 |
| Brandasylum Group Ltd. | Professional & scientific | 2019 |
| Bridgehead International Agency Ltd | Wholesale & retail | 2019 |
| Brightwater Business Development Ltd | Administrative & support | 2010 |
| Brim Developments Limited | Construction | 2003 |
| Brindley Farm Estate Holdings Ltd | Financial services | 2022 |
| Bringing YOU the Blooms Ltd | Wholesale & retail | 2021 |
| Britina Limited | Education | 2017 |
| British Appaloosa Society | Agriculture & fishing | 2003 |
| British China International Consulting Limited | Education | 2007 |
| Brizeon Limited | Information & communication | 2016 |
| Broad Residential Ltd | Real estate | 2022 |
| Broadleaze Consulting Ltd | Professional & scientific | 2019 |
| Brock Properties Ltd | Real estate | 2020 |
| Brook Beech Limited | Financial services | 2022 |
| Broughton Design & Architecture Limited | Professional & scientific | 2023 |
| Brown Creative Limited | Professional & scientific | 2009 |
| Brycla Limited | Manufacturing | 2010 |
| Bryval (Holdings) Limited | Real estate | 2022 |
| BSM Restoration Ltd | Administrative & support | 2025 |
| Bstm Limited | Professional & scientific | 2009 |
| Buddee Ltd | Professional & scientific | 2012 |
| Building Information Systems Ltd | Information & communication | 2007 |
| Bushbuy Construction Ltd | Construction | 2016 |
| Bushbuy Limited | Construction | 1987 |
| Business Garage Limited | Professional & scientific | 2015 |
| Business Winning Services Limited | Professional & scientific | 2014 |
| Butler Technologies UK Limited | Professional & scientific | 2020 |
| Butlins Elite Enterprises Limited | Arts & recreation | 2026 |
| BWM Consultancy Ltd | Professional & scientific | 2024 |
| C & G Joinery Limited | Manufacturing | 2004 |
| C&A Stone Associates Limited | Professional & scientific | 2017 |
| C&D Property(Wantage) Ltd | Construction | 2008 |
| C&N Property Investments Ltd | Real estate | 2022 |
| C&R Garden Maintenance Ltd | Other services | 2025 |
| C.M.P. Decorators Limited | Construction | 1999 |
| C.S.V. Contracts Limited | Construction | 2025 |