| Buildflex Limited | Construction | 2022 |
| Building Blocks and Bridges Limited | Health & social care | 2024 |
| Building Materials Direct Limited | Wholesale & retail | 2006 |
| Buildleap Ltd | Construction | 2018 |
| Buildleap Projects Ltd | Construction | 2026 |
| Buildstore Buying Group Limited | Wholesale & retail | 2025 |
| Buildstore Limited | Professional & scientific | 2013 |
| Buldok Limited | Transport & logistics | 2012 |
| Bulgarian School Prosveta Ltd | Education | 2014 |
| Bumbleb Ltd | Administrative & support | 2024 |
| Bunce (Ashbury) Limited | Manufacturing | 1971 |
| Bunce Court Management Limited | Households | 2013 |
| Bunce Dowling Ltd | Construction | 2024 |
| Bunce Restaurants Limited | Hospitality | 2018 |
| Bunkie Bakes Ltd | Hospitality | 2021 |
| Buratta Property Limited | Real estate | 2019 |
| Burderop Barns Management Company Limited | Households | 2011 |
| Burderop Bombers Softball Ltd | Arts & recreation | 2024 |
| Burderop Farming Company Limited | Agriculture & fishing | 2009 |
| Burderop Limited | Real estate | 2022 |
| Burdett Clinical Solutions Ltd | Professional & scientific | 2016 |
| Burgar Hill Wind Farm Limited | Extraterritorial | 1994 |
| Burger Land Limited | Manufacturing | 2025 |
| Burj at Harp and Crown Ltd | Hospitality | 2024 |
| Burj Swindon Restaurant Limited | Hospitality | 2016 |
| Burren Consulting Ltd | Information & communication | 2022 |
| Burton & Sons Electrical Ltd | Construction | 2023 |
| Burton Wells Trading Limited | Hospitality | 2019 |
| Bury South Management Company Limited | Real estate | 2013 |
| Bushton Ferris Limited | Construction | 1985 |
| Business Communication Consultants Ltd | Information & communication | 2015 |
| Business Declares Network | Other services | 2019 |
| Business LRY Ltd | Health & social care | 2018 |
| Business Solutions Delivery Limited | Information & communication | 2008 |
| Businesswebsite.Com Limited | Information & communication | 1993 |
| Busson's Elite Kickboxing Ltd | Arts & recreation | 2024 |
| Busson's Holdings Ltd | Financial services | 2024 |
| Busy LIL’ Motorhome Company Ltd | Administrative & support | 2016 |
| Butler & Brothers Limited | Information & communication | 2024 |
| Butler Toll Limited | Financial services | 2005 |
| Buysellswing Ltd | Other services | 2025 |
| Buzdu Speed Ltd | Transport & logistics | 2026 |
| Buzo Nexa Ltd | Manufacturing | 2026 |
| Buzz Cars(Swindon) Ltd | Transport & logistics | 2024 |
| Buzzsology Ltd | Information & communication | 2024 |
| BV Energy Limited | Professional & scientific | 2008 |
| BVG Associates Limited | Professional & scientific | 2006 |
| Bvlr HR Consultancy Ltd | Administrative & support | 2024 |
| BVR Yachting Ltd | Other services | 2022 |
| BXM Expeditions Limited | Arts & recreation | 2015 |
| BXM Holding Limited | Financial services | 2026 |
| BXM Media Limited | Information & communication | 2021 |
| BY Beauty Training Ltd | Other services | 2021 |
| By-The-Book Accounting Ltd | Professional & scientific | 2012 |
| BYE Design Builder Ltd | Construction | 2023 |
| Byericajane Ltd | Manufacturing | 2022 |
| Byford Glamping Limited | Hospitality | 2015 |
| Bynoor Ltd | Wholesale & retail | 2025 |
| Byte Codex Ltd | Transport & logistics | 2023 |
| Byzantine Recycling Ltd | Water & waste | 2025 |
| Bzodal Limited | Construction | 2010 |
| C & C Purton Limited | Other services | 2024 |
| C & C Reporting Solutions Limited | Professional & scientific | 2026 |
| C & C Software Solutions Limited | Extraterritorial | 2014 |
| C & Co Woodwork Limited | Construction | 2019 |
| C & G Concrete Pumping Ltd | Wholesale & retail | 2018 |
| C & G Electrical Services Limited | Construction | 2017 |
| C & H Healthcare Services Ltd | Health & social care | 2019 |
| C & R Boiler Services Limited | Manufacturing | 2018 |
| C & S PUB Holdings Limited | Hospitality | 2020 |
| C B I Systems Limited | Administrative & support | 2013 |
| C Brown Contracting Limited | Construction | 2022 |
| C Canto Ltd | Professional & scientific | 2025 |
| C D Bevan Limited | Other services | 2010 |
| C D Consultancy (Surrey) Limited | Administrative & support | 2018 |
| C H Enviro Ltd | Water & waste | 2024 |
| C H Jones Limited | Wholesale & retail | 1935 |
| C H Land & Property Ltd | Real estate | 2019 |
| C Hardie Mortgage & Protection Services Ltd | Financial services | 2020 |
| C Hortins Limited | Construction | 2025 |
| C Ince Systems Limited | Information & communication | 2014 |
| C L Shine Limited | Other services | 2018 |
| C M Locksmiths Limited | Administrative & support | 2023 |
| C P R Roofing Ltd | Construction | 2012 |
| C S Paving Limited | Construction | 2007 |
| C SLY Plumbing & Heating Limited | Construction | 2024 |
| C the K Afro Caribbean Limited | Wholesale & retail | 2016 |
| C&A Trading Ltd | Transport & logistics | 2023 |
| C&C Decontamination Services Limited | Administrative & support | 2025 |
| C&C Scenery Factory Ltd | Construction | 2012 |
| C&E K Ltd | Hospitality | 2025 |
| C&K Gardiner (Holdings) Limited | Manufacturing | 2025 |
| C&L Cleaning Solution Ltd | Administrative & support | 2025 |
| C&M Transilvania Food Ltd | Hospitality | 2022 |
| C-Change (Project) Limited | Health & social care | 2013 |
| C-Change Empowerment Ltd | Education | 2025 |
| C. H. Flats NO. 1 (Wootton Bassett) Limited | Hospitality | 1977 |
| C. H. Flats NO. 2 (Wootton Bassett) Limited | Households | 1977 |
| C. Wilson Contracting Ltd | Construction | 2023 |
| C.C.M.K. Limited | Hospitality | 1997 |