| Bargoed Homes Limited | Real estate | 2025 |
| Bargoed RFC Facilities Limited | Other services | 2026 |
| Barhen Property Management Limited | Households | 2025 |
| Bari Holdings Ltd | Real estate | 2017 |
| Bari Property Group Limited | Real estate | 2020 |
| Bariis & Hilib Buzzing Ltd | Hospitality | 2026 |
| Barion Solutions Limited | Wholesale & retail | 2025 |
| Barista Culture Ltd | Manufacturing | 2025 |
| Baritex Trade LP | | 2017 |
| Barix Ltd | Wholesale & retail | 2026 |
| Bark Boyz Ltd | Agriculture & fishing | 2023 |
| Barkat Citi Estates Limited | Real estate | 2024 |
| Barker Wilson Limited | Extraterritorial | 2026 |
| Barkingmad TV Limited | Information & communication | 2017 |
| Barkworks Limited | Professional & scientific | 2024 |
| Barleyfields Residential Limited | Real estate | 2015 |
| Barlow Systems Limited | Information & communication | 2018 |
| Barn Media Limited | Information & communication | 2010 |
| Barnes and Balham Limited | Construction | 2015 |
| Barnes Corporate Strategies Ltd | Professional & scientific | 2018 |
| Barnett White Ltd | Construction | 2026 |
| Barney Corp Ltd | Professional & scientific | 2023 |
| Barney Developments (Suffolk) Ltd | Construction | 2019 |
| Barnfield Road (Flat Management) Limited | Households | 1978 |
| Barnhaus Limited | Professional & scientific | 2013 |
| Barnton Enterprise Ltd | Administrative & support | 2026 |
| Barod Broadcast CYF. | Extraterritorial | 2023 |
| Barola Asset Management Limited | Real estate | 2016 |
| Barola Property Investments LLP | | 2013 |
| Baron Perfume Limited | Wholesale & retail | 2025 |
| Baron Street Management Company Limited | Households | 2026 |
| Baron VON Bohlen UND Halbach | Administrative & support | 2023 |
| Baron's Books Ltd | Wholesale & retail | 2024 |
| Baronfleet Limited | Information & communication | 2025 |
| Barons Cardiff Limited | Hospitality | 2025 |
| Barons Court Cardiff Limited | Real estate | 2019 |
| Barqo Ltd | Wholesale & retail | 2025 |
| Barracuda Energy Storage Limited | Mining & quarrying | 2020 |
| Barrada Alltrade Ltd | Other services | 2020 |
| Barrel Pools Ltd | Wholesale & retail | 2025 |
| Barrel Sauna UK Ltd | Manufacturing | 2026 |
| Barrel to Bottles Ltd | Wholesale & retail | 2022 |
| Barret Niel Ltd | Wholesale & retail | 2023 |
| Barrett Granger Limited | Extraterritorial | 2021 |
| Barri Davies Electric Payroll 01 Ltd | Administrative & support | 2018 |
| Barri Davies Electric Payroll Ltd | Administrative & support | 2022 |
| Barri Davies Electrics Payroll Limited | Administrative & support | 2021 |
| Barrians Way Residents Management Company Limited | Households | 1990 |
| Barrington Business Consultants Limited | Wholesale & retail | 2015 |
| Barron Design Limited | Professional & scientific | 2006 |
| Barrow Property Management Services Ltd | Real estate | 2018 |
| Barry & Rebecca Jones Ltd. | Health & social care | 2013 |
| Barry Computer Centre Ltd | Extraterritorial | 2016 |
| Barry Confections Ltd | Manufacturing | 2018 |
| Barry Cosslett Ltd | Construction | 1993 |
| Barry Dock Town Syndicate Limited(The) | Real estate | 1889 |
| Barry House Clearance (Vale) Ltd | Other services | 2018 |
| Barry Properties Ltd | Real estate | 2022 |
| Barry Rubbish Removals Limited | Other services | 2006 |
| Barry Smith Education Ltd | Education | 2021 |
| Barry TEW Consulting Ltd | Professional & scientific | 2008 |
| Barry Wheel Centre Ltd | Wholesale & retail | 2026 |
| Barryaservice Limited | Manufacturing | 2025 |
| Barryberry Ltd | Wholesale & retail | 2024 |
| Bart 78 Ltd | Transport & logistics | 2016 |
| Bart Management Limited | Construction | 2019 |
| Bart Retail Solutions Limited | Wholesale & retail | 2024 |
| Barth Orthodontics Limited | Health & social care | 2008 |
| Bartholdi Limited | Manufacturing | 1961 |
| Bartholomew Hawkins Limited | Financial services | 2005 |
| Bartle Homes Ltd | Real estate | 2021 |
| Barton Greenwood and SON Limited | Agriculture & fishing | 2018 |
| Bartopia Ltd | Wholesale & retail | 2017 |
| Baruchglobal Limited | Wholesale & retail | 2022 |
| Barukh Enterprises Limited | Professional & scientific | 2012 |
| Barvion Ltd | Wholesale & retail | 2026 |
| Barwaaqo Care Ltd | Health & social care | 2024 |
| BAS Property Management Ltd | Real estate | 2025 |
| Basair Academy Ltd | Education | 2025 |
| Basarabia Group Ltd | Financial services | 2019 |
| Basdconsultancy Ltd | Information & communication | 2020 |
| Base 7 Ltd | Health & social care | 2026 |
| Base Accommodation & Property Services Ltd | Hospitality | 2016 |
| Base Properties (Cardiff) Limited | Real estate | 2016 |
| Base Silver Tech Ltd | Information & communication | 2025 |
| Base Strength and Fitness Ltd | Arts & recreation | 2020 |
| Base Support Services Ltd | Public administration | 2011 |
| Baseball Softball Gwalia CIC | Education | 2019 |
| Basebid Limited | Arts & recreation | 2012 |
| Basecamp Banquet CYF | Hospitality | 2026 |
| Baseline Software Ltd | Information & communication | 2015 |
| Basemart Limited | Wholesale & retail | 2025 |
| Basement Trims Ltd | Other services | 2026 |
| Basetheme Limited | Real estate | 2005 |
| Baseworx Technologies UK Limited | Information & communication | 2023 |
| Bash Dining Company Limited | Manufacturing | 2023 |
| Bash Private Limited | Information & communication | 2022 |
| Bash Wheatley Arts Limited | Wholesale & retail | 2017 |
| Basha Accounting Ltd | Professional & scientific | 2017 |
| Basi United Ltd | Wholesale & retail | 2025 |