| Asia Feast Ltd | Hospitality | 2015 |
| ASJ Capital Ltd | Real estate | 2021 |
| Aspect Business Communications Ltd | Information & communication | 2008 |
| Asphalt Infrastructure Limited | Construction | 2025 |
| Aspire Mrcog Ltd | Extraterritorial | 2022 |
| Aspire Property Improvements Ltd | Construction | 2025 |
| Asset and Infrastructure Design Ltd | Professional & scientific | 2018 |
| Asset and Infrastructure Engineering Ltd | Construction | 2015 |
| Assist Air Limited | Extraterritorial | 2010 |
| Assisted Project Solutions Limited | Real estate | 2023 |
| Associated Consultants Limited | Information & communication | 1989 |
| Assure Home Surveys Ltd | Professional & scientific | 2025 |
| Assured Legal Services Limited | Professional & scientific | 2024 |
| Asterbrook Limited | Real estate | 2007 |
| Aston and Willson LLP | | 2021 |
| Astrans Motors Ltd | Wholesale & retail | 2012 |
| Astro QP Solutions Ltd | Professional & scientific | 2022 |
| Atex Properties Limited | Real estate | 2006 |
| ATG Site Services Limited | Transport & logistics | 2014 |
| Athena Abode Ltd | Real estate | 2024 |
| Athina Art Ltd | Wholesale & retail | 2023 |
| ATJ Healthcare Limited | Health & social care | 2021 |
| Atksa Traders Ltd | Wholesale & retail | 2023 |
| Atlanta Building & Developments Ltd | Construction | 2019 |
| Atlantic Machinery Limited | Manufacturing | 1994 |
| Atlantic Plastics Limited | Manufacturing | 1974 |
| Atts Training Limited | Transport & logistics | 2014 |
| AU Ventures Ltd | Wholesale & retail | 2026 |
| Audi VW Specialist Bridgend Ltd | Wholesale & retail | 2025 |
| Audio Connect Limited | Information & communication | 2025 |
| Aune Consulting Ltd | Professional & scientific | 2015 |
| Aura Barns Ltd | Real estate | 2026 |
| Aurora Staffing Solutions Limited | Administrative & support | 2022 |
| Auroran CHI CIC | Hospitality | 2025 |
| Auspi UK Limited | Manufacturing | 2017 |
| Authentic Connections Limited | Professional & scientific | 2022 |
| Autosecure Technologies Limited | Administrative & support | 2009 |
| Autostop Tyre & Autocare Centre Limited | Wholesale & retail | 2000 |
| Autotrak Portable Roadways Limited | Administrative & support | 1994 |
| Autovia Motors Ltd | Wholesale & retail | 2020 |
| Autumn Peak Limited | Administrative & support | 1996 |
| Autumn Walks Ltd | Information & communication | 2024 |
| AV Traders Ltd | Wholesale & retail | 2025 |
| Avia Sports Cars Limited | Wholesale & retail | 2000 |
| AW Business Consultancy Limited | Information & communication | 2014 |
| Awen Consult Limited | Professional & scientific | 2025 |
| Awen Cultural Trust | Health & social care | 2015 |
| Awen Trading Limited | Other services | 2015 |
| Axiom Structural Design Ltd | Construction | 2020 |
| AYI Animations Limited | Arts & recreation | 2016 |
| Azeca Properties Limited | Real estate | 2018 |
| Azool Media Limited | Information & communication | 2023 |
| Aztec Glass and Balustrade Ltd | Manufacturing | 2019 |
| Azura Trading Ltd | Financial services | 2023 |
| B & M Accommodation Limited | Hospitality | 2017 |
| B & W Specialist Tunnelling Contractors Limited | Construction | 2004 |
| B END Leisure Ltd | Hospitality | 2021 |
| B G Pubs Ltd | Hospitality | 2025 |
| B IS for Buff Ltd | Manufacturing | 2025 |
| B P Blasting Solutions Limited | Administrative & support | 2007 |
| B V S (Wales) Limited | Wholesale & retail | 2003 |
| B. and W. Tunnelling Limited | Construction | 1985 |
| B.D.S Logistics Ltd | Transport & logistics | 2018 |
| B.G.S Motors & Mowers Ltd. | Manufacturing | 1994 |
| B.M.R. (Holdings) Limited | Real estate | 1954 |
| Baby Swimming Bristol LLP | | 2015 |
| Baby Swimming Duckling Dive LLP | | 2017 |
| Baby Swimming Glamorgan LLP | | 2013 |
| Back & Neck Chiropractic Clinic Ltd | Health & social care | 2006 |
| Back to My Roots Limited | Professional & scientific | 2009 |
| Backcote Limited | Extraterritorial | 2026 |
| Backfray Limited | Extraterritorial | 2026 |
| Backmoor Limited | Extraterritorial | 2025 |
| Backvale Limited | Extraterritorial | 2026 |
| Backwatch Safety Products Limited | Transport & logistics | 1998 |
| Badgerholt Holdings Ltd | Financial services | 2025 |
| BAE Coffi - Cymru Ltd | Wholesale & retail | 2013 |
| Bakers Television & Electrical Ltd | Wholesale & retail | 2013 |
| Baldiverse Ltd | Other services | 2025 |
| Ballitarsin Limited | Hospitality | 2021 |
| Bamf Trades Ltd | Construction | 2026 |
| Bang-On Brewery Limited | Manufacturing | 2016 |
| Bano Recycling UK Limited | Manufacturing | 2013 |
| Baobab Bach CIC | Hospitality | 2021 |
| Bar 16 CIC | Hospitality | 2021 |
| Bara Cafe and Curry House Limited | Hospitality | 2025 |
| Bara Takeaway Limited | Hospitality | 2024 |
| Baraka Traders Ltd | Hospitality | 2019 |
| Barc (Bridgend Adult Resource Centre) Community Outreach Centre Community Interest Company | Health & social care | 2018 |
| Bare Squared Ltd | Professional & scientific | 2017 |
| Barguz Foods Ltd | Hospitality | 2025 |
| Bark With Pride Limited | Other services | 2024 |
| Barkers Lodge Ltd | Other services | 2020 |
| Barkmere Limited | Extraterritorial | 2026 |
| Barnmill Consultancy Ltd | Professional & scientific | 2022 |
| Baronfray Limited | Construction | 2025 |
| Baronlea Limited | Extraterritorial | 2026 |
| Baronmay Limited | Administrative & support | 2025 |
| Baronoak Limited | Extraterritorial | 2026 |
| Barry Keene Limited | Other services | 2006 |