| Bassett Property Holdings Ltd | Real estate | 2009 |
| Bassetts (South Wales) Ltd | Wholesale & retail | 2010 |
| Bassetts (Swansea) Ltd | Wholesale & retail | 1991 |
| Bassetts (Wales) Ltd | Wholesale & retail | 1995 |
| Bassom Moore Limited | Professional & scientific | 2015 |
| Bastek Management Ltd | Administrative & support | 2020 |
| BAT Electrics Limited | Construction | 2025 |
| Bath Liberty Ltd | Hospitality | 2017 |
| Batty Adventures Ltd | Extraterritorial | 2021 |
| Bauket and Sons Limited | Education | 2022 |
| Bault Cabs Ltd | Transport & logistics | 2025 |
| Bay Aesthetics Ltd | Other services | 2019 |
| Bay Apartments Limited | Professional & scientific | 2004 |
| Bay Carpentry Ltd | Construction | 2023 |
| Bay Cleaning Limited | Administrative & support | 2023 |
| Bay Counselling Services Ltd | Health & social care | 2020 |
| Bay Decorating Services Limited | Construction | 2013 |
| Bay Digital and Data Services Ltd | Information & communication | 2023 |
| Bay Estate Agents Limited | Real estate | 2000 |
| Bay Film Studios Ltd | Extraterritorial | 2015 |
| Bay Insulation and Loft Boarding Ltd | Construction | 2026 |
| Bay Landscapes Limited | Administrative & support | 2006 |
| Bay Psychotherapy & Supervision Limited | Health & social care | 2021 |
| Bay Quantity Surveyors Ltd | Construction | 2022 |
| Bay Sanctuary Group Limited | Other services | 2025 |
| Bay Sanctuary Ltd | Other services | 2025 |
| Bay Security Ltd | Administrative & support | 2018 |
| Bay Surgical Limited | Wholesale & retail | 2025 |
| Bay Tree Enterprises Limited | Wholesale & retail | 1971 |
| Bay View Court (Tycoch) Management Company Limited | Households | 2018 |
| Bay View Management Limited | Real estate | 2015 |
| Bay View Retreats LLP | | 2016 |
| Bay VUE Property Management Ltd | Real estate | 2025 |
| Baya Consulting Ltd | Information & communication | 2018 |
| Bayland Motors Ltd | Wholesale & retail | 2015 |
| Bayliss Brickwork Ltd | Construction | 2020 |
| Bayonne Limited | Construction | 2015 |
| Baypark Properties Limited | Professional & scientific | 2000 |
| Bayside Building Ltd | Construction | 2026 |
| Bayside Construction (Swansea) Ltd | Construction | 2024 |
| Baysoft Software Development Limited | Information & communication | 1998 |
| Baystays Limited | Hospitality | 2018 |
| Baysu Ltd | Real estate | 2025 |
| Bayswater Properties (Swansea) Limited | Real estate | 1952 |
| Baytan Limited | Other services | 2022 |
| Bayue Ecommerce Services Ltd | Administrative & support | 2017 |
| Bayview Gower Collection Limited | Hospitality | 2023 |
| Bayview Oxwich Holdings Limited | Financial services | 2026 |
| Baywifi (UK) Limited | Manufacturing | 2019 |
| BB List Limited | Other services | 2003 |
| BB2 Ltd | Construction | 2006 |
| BB3 Limited | Administrative & support | 2009 |
| Bbht Propco Ltd | Hospitality | 2025 |
| Bbsa Propco Ltd | Financial services | 2021 |
| BC 99 Ltd | Other services | 2015 |
| BCD Props CYF | Real estate | 2021 |
| BDF OPS UK Ltd | Hospitality | 2019 |
| Bdfsa Propco Ltd | Financial services | 2021 |
| BDH Solutions CYF | Health & social care | 2021 |
| BDS Supermarket Ltd | Wholesale & retail | 2025 |
| BE23 Coffee & Kitchen Ltd | Hospitality | 2020 |
| Beach Dogs Ltd | Other services | 2025 |
| Beachtree Builders Ltd | Construction | 2024 |
| Beacon Rivers Music and Publishing Ltd | Information & communication | 2014 |
| Beacons Electrical Engineering Ltd | Construction | 2016 |
| Beacons Tactical Cyber Ltd | Professional & scientific | 2025 |
| Beaconsfield Court Residents Association Limited | Households | 1982 |
| Beak @ 28 Ltd | Health & social care | 2013 |
| Bear Essentials Limited | Extraterritorial | 2013 |
| Bear Hair Ltd | Health & social care | 2025 |
| Bearhouse Logistics Limited | Transport & logistics | 2019 |
| Bearing Suppliers (Clydach) Limited | Administrative & support | 2007 |
| Beat Boulevard Ltd | Wholesale & retail | 2025 |
| Beau Monde Outlooks Limited | Education | 2021 |
| Beauden B Rail Ltd | Construction | 2023 |
| Beaumont FOX & Partners Ltd | Information & communication | 2025 |
| Beaumont Pensions Limited | Financial services | 2020 |
| Beaumont-Heritage Ltd | Professional & scientific | 2016 |
| Beauty by Amanda Ltd | Other services | 2024 |
| Beauty by Lucy Ltd. | Other services | 2024 |
| Beauty Centre & Training Swansea Ltd | Other services | 2022 |
| Beauty Therapy Suite Limited | Other services | 2006 |
| Beauty UN Limited | Extraterritorial | 2014 |
| Beauty-Licious Hair and Beauty Limited | Other services | 2017 |
| Beauview Properties Limited | Real estate | 2016 |
| Bebeautifulbeauty Ltd | Other services | 2023 |
| Bedminster Takeaway Ltd | Hospitality | 2023 |
| Bedrich Homes Holdings Ltd | Financial services | 2026 |
| Bedrich Homes Ltd | Construction | 2024 |
| BEE Clean SA3 Ltd | Administrative & support | 2024 |
| BEE Independent Limited | Hospitality | 2012 |
| Beechcroft Technologies Limited | Information & communication | 2023 |
| Beechdene Engineering Limited | Professional & scientific | 2015 |
| Beechwood Road Limited | Hospitality | 2026 |
| Beehive Homes Ltd | Real estate | 2021 |
| Beejaay Traders Limited | Wholesale & retail | 2013 |
| Beejays Property Limited | Real estate | 2025 |
| Beelong Ltd | Administrative & support | 2026 |
| Being the Best of YOU Ltd | Professional & scientific | 2022 |
| Belasco Holdings Limited | Financial services | 2025 |