| Abertawe Carpentry & Construction Ltd | Construction | 2011 |
| Abertawe Chiropractic Clinic Ltd | Health & social care | 2022 |
| Abertawe Cleaning Services Ltd | Other services | 2024 |
| Abertawe Combat Club Ltd | Arts & recreation | 2023 |
| Abertawe Electrical Solutions Limited | Construction | 2025 |
| Abertawe Exterior Cleaning Limited | Administrative & support | 2025 |
| Abertawe Handyman Ltd | Construction | 2024 |
| Abertawe Heating & Plumbing Ltd | Construction | 2013 |
| Abertawe Interiors Ltd | Administrative & support | 2024 |
| Abertawe Metal Recycling Limited | Water & waste | 2014 |
| Abertawe Property Services Limited | Real estate | 2014 |
| Abertawe Residential Care Ltd | Health & social care | 2019 |
| Abertawe Roofing & Building Ltd | Construction | 2025 |
| Abertawe Roofing Ltd | Construction | 2026 |
| Abertawe Sectional Buildings Limited | Construction | 2013 |
| Abertawe Systemic Therapy / Swansea Family Therapy Limited | Health & social care | 2022 |
| Abertawe Travel Ltd | Transport & logistics | 2024 |
| Abest Services Limited | Professional & scientific | 2013 |
| ABG Group Limited | Financial services | 2026 |
| Abgardens Ltd | Administrative & support | 2024 |
| ABI Fabrication and Engineering Ltd | Manufacturing | 2020 |
| ABI MAC Ltd | Education | 2025 |
| ABI Snow Limited | Other services | 2018 |
| Abieduc Ltd | Education | 2022 |
| Abigails Hair Studio Ltd | Other services | 2018 |
| Abington Law Ltd | Professional & scientific | 2020 |
| ABL Change Ltd | Information & communication | 2023 |
| ABL14 Limited | Financial services | 2014 |
| Able Hands Exhibition Services (UK) Ltd | Administrative & support | 2013 |
| Able Property (Swansea) Ltd | Real estate | 2018 |
| About Drains Ltd | Construction | 2024 |
| Above Roofing Ltd | Construction | 2024 |
| ABR Electrical Services (South Wales) Ltd | Construction | 2014 |
| Abrahams Consulting Engineers Limited | Professional & scientific | 2025 |
| Abrowe Property Ltd | Real estate | 2021 |
| Abruras Limited | Health & social care | 2020 |
| Absent Limited | Health & social care | 2016 |
| Absolute Accountancy Services Limited | Professional & scientific | 2017 |
| Absolute Events Management Limited | Arts & recreation | 2025 |
| Absolutely ALL Ltd | Construction | 2003 |
| ABT Property Maintenance Ltd | Construction | 2025 |
| ABU Property Ltd | Real estate | 2015 |
| Abundant Travel Consult Ltd | Administrative & support | 2025 |
| ABW Executive Travel Ltd | Transport & logistics | 2025 |
| ABX Slate and Stone Limited | Wholesale & retail | 2004 |
| ABZ Carpentry Ltd | Construction | 2004 |
| AC Box Ltd | Hospitality | 2018 |
| AC DC Builders Ltd | Construction | 2025 |
| AC Electrical Engineers Ltd | Construction | 2019 |
| AC Electricals Swansea Ltd | Wholesale & retail | 2024 |
| AC Jenkins Limited | Transport & logistics | 1999 |
| AC RIG Ltd | Transport & logistics | 2022 |
| Acaciatastefully Ltd | Manufacturing | 2019 |
| Academic UK Global Centre CIC | Education | 2023 |
| Academic-Uk Ltd | Education | 2016 |
| Academy of Sinology UK | Education | 2016 |
| Acadinn Limited | Education | 2025 |
| Access 4 Life Ltd | Health & social care | 2010 |
| Access Awards Ltd | Education | 2025 |
| Access MED Ltd | Professional & scientific | 2025 |
| Access Training (Digital) Ltd | Education | 2025 |
| Access Training (Infrastructure) Ltd | Education | 2025 |
| Access Training (Innovations) Ltd | Administrative & support | 2025 |
| Access Training (Trades) Ltd | Education | 2025 |
| Access Training (Wales) Limited | Education | 2003 |
| Access Training (Wellbeing) Ltd | Education | 2025 |
| Access Training Enterprises Ltd | Financial services | 2024 |
| Access Training Works Ltd | Education | 2025 |
| Access Works Ltd | Education | 2025 |
| Accessibility Powys Ltd | Information & communication | 2005 |
| Accounts and Payroll Limited | Professional & scientific | 2002 |
| Accounts Consulting Ltd | Professional & scientific | 2020 |
| Accsellerate Ltd | Professional & scientific | 2025 |
| Ace Accident Repair Centre Ltd | Wholesale & retail | 2009 |
| Ace Alloy Diamond Cutting Limited | Wholesale & retail | 2019 |
| Ace ARC Properties Ltd | Real estate | 2024 |
| Ace Brasseries Holdings Limited | Hospitality | 2018 |
| Ace Brasseries Limited | Hospitality | 2010 |
| Ace Business Solutions Group Ltd | Professional & scientific | 2020 |
| Ace Buy-To-Let Ltd | Real estate | 2018 |
| Ace Cleaning & Hoarding Services Ltd | Administrative & support | 2025 |
| Ace Clwb Nofio Llanelli Ltd | Education | 2026 |
| Ace of Fades Barber Ltd | Other services | 2021 |
| Ace Roofing & Scaffolding Ltd | Construction | 2025 |
| Ace Swim School Ltd | Education | 2018 |
| Ace's Desserts Ltd | Hospitality | 2021 |
| Aceo Properties Limited | Real estate | 2010 |
| Ace’S Desserts 2 Ltd | Hospitality | 2023 |
| Achieved Compliance Advocacy Limited | Professional & scientific | 2017 |
| ACJ Housing Ltd | Real estate | 2024 |
| Ackland Professional Ltd | Hospitality | 2021 |
| ACL Mobile Repairs Ltd | Other services | 2018 |
| Acmel Security and Shipping Consultancy Ltd | Professional & scientific | 2025 |
| ACO Training Limited | Education | 2007 |
| Acoma Real Estate (UK) Limited | Real estate | 2021 |
| Aconsultingi Limited | Information & communication | 2025 |
| Acorn Construction & Concrete Ltd | Construction | 2020 |
| Acorn Nursery Limited | Health & social care | 2020 |
| Acorn Properties & Developments Ltd | Hospitality | 2025 |
| Acornrise Limited | Arts & recreation | 2001 |