| Asyra Ltd | Extraterritorial | 2025 |
| ATF Properties Limited | Real estate | 2023 |
| Athabasca Engineering Ltd | Professional & scientific | 2022 |
| Atire Pro Clean Pressure Washing Ltd | Administrative & support | 2025 |
| Atom Fabrications Limited | Manufacturing | 1997 |
| Attas Investments Limited | Real estate | 2021 |
| Atum Ltd | Construction | 2018 |
| Autobond (Body Shop) Limited | Wholesale & retail | 2005 |
| Autocentres Limited | Wholesale & retail | 2000 |
| Avondale Exhibitions Limited | Construction | 2009 |
| Avondale Group Holdings Ltd | Real estate | 2021 |
| Avondale Motorpark Ltd | Wholesale & retail | 2014 |
| Avondale Service Station Ltd | Wholesale & retail | 2007 |
| Avondale Storage Ltd | Transport & logistics | 2022 |
| Avondale Vehicle Hire Limited | Administrative & support | 2025 |
| Awaken Group Limited | Education | 2015 |
| Awenydd Business Consultancy Ltd | Professional & scientific | 2014 |
| Awesational Ltd | Information & communication | 2026 |
| Axis Controls Limited | Information & communication | 1997 |
| Azlan & Minsa Ltd | Wholesale & retail | 2025 |
| Aztec Property Tredegar Ltd | Construction | 2024 |
| Aztech Environmental Services (UK) Limited | Water & waste | 1998 |
| Aztech Fuel Services UK Ltd | Wholesale & retail | 2020 |
| B E Baker and Sons Limited | Agriculture & fishing | 2005 |
| B LET Ltd | Real estate | 2026 |
| B Roberts Services Ltd | Administrative & support | 2019 |
| B.A.S Limited | Manufacturing | 1982 |
| Badz Collectables Limited | Wholesale & retail | 2025 |
| Badzgaming Ltd | Wholesale & retail | 2022 |
| Balaam Limited | Construction | 2012 |
| Baltic Ponds Limited | Households | 2026 |
| Barrian Claims Ltd | Financial services | 2011 |
| Bbyz Ltd | Hospitality | 2026 |
| BD King Ltd | Hospitality | 2019 |
| Be:Vito Limited | Manufacturing | 2020 |
| Beacon Energy Ltd | Construction | 2025 |
| Bear Front Limited | Wholesale & retail | 2025 |
| Beaufort Property Development Limited | Construction | 2001 |
| Beckett Medico Legal Services Ltd | Professional & scientific | 2026 |
| Belle Partnership (Construction) Limited | Construction | 2023 |
| Belle VUE (Cwmbran) Limited | Real estate | 2012 |
| Belle VUE Nursery Limited | Education | 2002 |
| Besni Food Ltd | Hospitality | 2025 |
| Bespoke Laser UK Ltd | Professional & scientific | 2018 |
| Best in Business Limited | Wholesale & retail | 2023 |
| Beta Lettings Ltd | Real estate | 2024 |
| Bibi Estate Agents Limited | Real estate | 2025 |
| Big Game Sports Limited | Wholesale & retail | 2024 |
| Big Mouse Productions Ltd | Information & communication | 2010 |
| Bineezy Ltd | Administrative & support | 2024 |
| Bitpipe Solutions Ltd | Information & communication | 2011 |
| BITS4VANS Ltd | Wholesale & retail | 2018 |
| Black Mountain Property Services Limited | Construction | 2021 |
| Black PEPPER6 Ltd | Hospitality | 2025 |
| Blaen Bran Community Woodland | Agriculture & fishing | 2004 |
| Blaenavon Motor Company Limited | Wholesale & retail | 1961 |
| Blaenbran Consulting Ltd | Professional & scientific | 2021 |
| Blazecraft Construction Limited | Construction | 2011 |
| Bloc Group Limited | Financial services | 2020 |
| Blue Mountain Air Conditioning Ltd | Construction | 2006 |
| Bluebird Motor Company Ltd | Wholesale & retail | 2026 |
| Blueprint Energy Ltd | Administrative & support | 2016 |
| Board Assist Ltd | Professional & scientific | 2022 |
| Boiler Burner Maintenance Limited | Manufacturing | 1998 |
| Bookme Agency Ltd | Arts & recreation | 2019 |
| Boroughsafe Ltd | Administrative & support | 2025 |
| Boss EMY Limited | Construction | 2026 |
| Boycott Properties Ltd | Real estate | 2021 |
| Bradford-Smith Homes Ltd | Real estate | 2020 |
| Brainstates Inc. Ltd | Professional & scientific | 2023 |
| Brandon Lewis Eco Kitchenware Limited | Wholesale & retail | 2024 |
| Brandon Loder Limited | Transport & logistics | 2025 |
| Brecon Pet and Garden Centre Limited | Wholesale & retail | 2015 |
| Breeze Accountants Ltd | Professional & scientific | 2025 |
| Brewed Futures CIC | Other services | 2026 |
| Bright Ember Consultancy Limited | Professional & scientific | 2025 |
| Brist Drive Systems UK Ltd | Manufacturing | 2024 |
| Bristol Traffic & Analytics Surveys Limited | Professional & scientific | 2026 |
| Broadway Property Rentals Ltd | Real estate | 2024 |
| Brockweir Clinic Ltd | Health & social care | 2019 |
| Broomfield Oates Investments Ltd | Real estate | 2021 |
| Brown Davies Accountants Limited | Professional & scientific | 2018 |
| Brown Davies Limited | Extraterritorial | 2018 |
| BRW Data Solutions Ltd | Information & communication | 2025 |
| Bryn Digital Ltd | Information & communication | 2026 |
| Brynglas Limited | Financial services | 2015 |
| BSN Automotive Solutions Ltd | Wholesale & retail | 2026 |
| Buckland Group Holdings Ltd | Financial services | 2025 |
| Buffy BBQ Ltd | Hospitality | 2025 |
| Building Bloc Limited | Construction | 2020 |
| Bulmer Properties Ltd | Hospitality | 2016 |
| Bundlesofjoy Ltd | Wholesale & retail | 2026 |
| Bush Pepper Events Ltd | Hospitality | 2024 |
| Business With RHI Ltd | Professional & scientific | 2026 |
| Butch JRS Ltd | Hospitality | 2025 |
| Buy and Sell Properties Limited | Real estate | 2025 |
| Bvaah Limited | Wholesale & retail | 2024 |
| Bwyd DA Catering Ltd | Hospitality | 2022 |
| C J Carpentry Services Ltd | Manufacturing | 2024 |
| C Reid Carpentry Ltd | Construction | 2026 |