| Bevans Carpets & Flooring Ltd | Wholesale & retail | 2022 |
| Big a Band Store Ltd | Professional & scientific | 2018 |
| Big Lemon Creative Limited | Information & communication | 2014 |
| Bike Hire UK Limited | Manufacturing | 2016 |
| Biocraft Ltd | Construction | 2025 |
| Biocraft South East Ltd | Construction | 2023 |
| Biocraft South West Limited | Construction | 2012 |
| Biospatial Insights Ltd | Information & communication | 2024 |
| Bishop House Properties Limited | Real estate | 2002 |
| Bishops Court West (Brecon) Limited | Administrative & support | 2013 |
| Black Knight Management Ltd | Health & social care | 2019 |
| Black Mountain Activities Limited | Arts & recreation | 2003 |
| Black Mountain Adventure Ltd | Administrative & support | 2025 |
| Black Mountain Bespoke Breaks Limited | Hospitality | 2021 |
| Black Mountain Forestry Ltd | Agriculture & fishing | 2018 |
| Black Mountains Acupuncture Limited | Other services | 2011 |
| Black Mountains College Project | Education | 2018 |
| Black Mountains Developments Ltd | Real estate | 2025 |
| Black Mountains Farm Services Ltd | Agriculture & fishing | 2020 |
| Black Mountains Gliding Club | Arts & recreation | 1996 |
| Black OX Inn Limited | Hospitality | 2011 |
| Blackwood Plumbing & Heating Limited | Construction | 2013 |
| Blaenycwm Estate Limited | Real estate | 2021 |
| Bludog Arts Ltd | Arts & recreation | 2017 |
| Blue Sky Equity Limited | Financial services | 2017 |
| Blues Matters Limited | Information & communication | 2013 |
| Bond Alarms Limited | Administrative & support | 2003 |
| Book Scaffolding Ltd | Construction | 2018 |
| Boughrood Harness Racing | Arts & recreation | 2005 |
| BPB Developments Limited | Construction | 2021 |
| Brecknock Farmers Market Limited | Wholesale & retail | 2001 |
| Brecon and District Mind | Health & social care | 2011 |
| Brecon Antiques Limited | Wholesale & retail | 2021 |
| Brecon Barrells Limited | Wholesale & retail | 2021 |
| Brecon Beacons Tourism | Other services | 2009 |
| Brecon Bowling Club Limited | Arts & recreation | 2016 |
| Brecon Buzz CIC | Other services | 2021 |
| Brecon Car Rentals Limited | Administrative & support | 1996 |
| Brecon Cathedral Tithebarn Company Limited | Wholesale & retail | 1995 |
| Brecon Chocolates Limited | Manufacturing | 2012 |
| Brecon Cinnamon Ltd | Hospitality | 2024 |
| Brecon Communication Services Limited | Information & communication | 2020 |
| Brecon Dust Busters Limited | Other services | 2024 |
| Brecon Jazz | Arts & recreation | 2023 |
| Brecon Jazz Festival Ltd. | Arts & recreation | 1996 |
| Brecon N HAY TAP Ltd | Hospitality | 2018 |
| Brecon Nail NM Ltd | Other services | 2023 |
| Brecon Properties Limited | Real estate | 2021 |
| Brecon Retreats Limited | Hospitality | 2026 |
| Brecon Rugby Football Club Limited | Arts & recreation | 2015 |
| Brecon Scaffolding Limited | Construction | 2001 |
| Brecon Self Storage Limited | Real estate | 2016 |
| Brecon Storage and Removals Ltd | Transport & logistics | 2018 |
| Brecon Take Aways Limited | Transport & logistics | 2026 |
| Brfc Rugby Ltd | Arts & recreation | 2023 |
| Brics Properties Ltd | Real estate | 2020 |
| Britannia Civil Reserve CIC | Administrative & support | 2026 |
| British Sarozal Limited | Other services | 1946 |
| Bronllys Estates Limited | Construction | 2018 |
| Brooks Property Strategy Ltd | Real estate | 2026 |
| Brooks-Lewis Construction Limited | Construction | 2017 |
| Brookside Care Home Limited | Health & social care | 2003 |
| Bryan Appleyard Ltd | Other services | 2013 |
| Brythonic Yachts Limited | Manufacturing | 2020 |
| BSL Express Service Limited | Other services | 1976 |
| Buckland Pet Resort Ltd | Agriculture & fishing | 2025 |
| Building Standards Consultancy Ltd | Professional & scientific | 2014 |
| Buildonmeta Ltd | Extraterritorial | 2022 |
| Builth Building Services Limited | Construction | 2002 |
| Burgess Land Ltd | Real estate | 2016 |
| Buttons Nursery Limited | Health & social care | 2014 |
| Bwlch Leisure Limited | Real estate | 2025 |
| Bywiog Limited | Professional & scientific | 2026 |
| C & T Bain Ltd | Construction | 2003 |
| C 2 J Design Limited | Professional & scientific | 2007 |
| C C Smiff Limited | Information & communication | 2011 |
| C.B. Flats Limited | Real estate | 2002 |
| C.H.Marlow Limited | Wholesale & retail | 1960 |
| CA Development Consultants Limited | Professional & scientific | 2007 |
| CAE Pentre Limited | Households | 2014 |
| Caelais Welsh Foods Limited | Manufacturing | 2009 |
| Calch TY Mawr Lime Limited | Extraterritorial | 2009 |
| Calibre Connections IT Limited | Administrative & support | 2015 |
| Camden Court Residents Management Limited | Households | 1990 |
| Camperholics Limited | Wholesale & retail | 2022 |
| Canbury Interiors Contracting Ltd | Construction | 2023 |
| Cannon Campers UK Limited | Other services | 2023 |
| Capel Y Maen Ltd | Real estate | 2024 |
| Captain Brown's Pizza's Ltd | Wholesale & retail | 2019 |
| Card Property Developments Ltd | Construction | 2020 |
| Cardiff Biologicals Limited | Extraterritorial | 2006 |
| Cardiff Protides Limited | Extraterritorial | 2005 |
| Cariads Local Ltd | Information & communication | 2014 |
| Carla Rapoport Art Network CIC | Health & social care | 2024 |
| Cartrefi TY Mawr CYF | Construction | 2019 |
| Castle Farm Feeds Ltd | Wholesale & retail | 2017 |
| Castle Hotel Llandovery Limited | Hospitality | 2010 |
| Castle WYE Limited | Real estate | 2017 |
| Catherine Etchell Associates Limited | Professional & scientific | 2008 |
| CBS Distribution Ltd | Wholesale & retail | 2010 |