| Apollo Blinds S.W. Ltd | Wholesale & retail | 2017 |
| Apollo Builders Group Ltd | Construction | 2019 |
| Apollo Cars Ltd | Wholesale & retail | 2014 |
| Apollo Digital Ltd | Information & communication | 2015 |
| Apollo Etouch Limited | Information & communication | 2016 |
| Apollo Healthcare Limited | Professional & scientific | 2016 |
| Apollo Minibus & Coach Hire Limited | Transport & logistics | 2004 |
| Apollo Pizza Cardiff Ltd | Hospitality | 2026 |
| Apollo Property Sourcing Ltd | Real estate | 2019 |
| Apollo Tide Limited | Administrative & support | 2021 |
| Apollo UK Contracts Ltd | Administrative & support | 2019 |
| Apollo's Llanedeyrn & Pentwyn Amateur Boxing Club CIC | Arts & recreation | 2021 |
| Apollon Holding Ltd | Financial services | 2024 |
| Apoo UK PVT Limited | Wholesale & retail | 2025 |
| Apostle Films Ltd | Information & communication | 2016 |
| Apotix Services Ltd | Wholesale & retail | 2021 |
| Apotoma Services Ltd | Wholesale & retail | 2021 |
| App Management Cardiff Ltd | Professional & scientific | 2025 |
| App Vista Limited | Information & communication | 2025 |
| Appaisle Ltd | Wholesale & retail | 2024 |
| Appandtap Limited | Information & communication | 2024 |
| Appanna Healthcare Ltd | Health & social care | 2019 |
| Appatyzers Urban Cuisine Ltd | Hospitality | 2019 |
| Appcompat Limited | Information & communication | 2018 |
| Appcycle Ltd | Information & communication | 2025 |
| Appeggio Ltd | Information & communication | 2015 |
| Appella Sparkle Limited | Administrative & support | 2021 |
| Appeltech Ltd | Other services | 2023 |
| Appetise Marketing Limited | Wholesale & retail | 2017 |
| Appfairly Ltd | Information & communication | 2025 |
| Apphance Limited | Information & communication | 2025 |
| Apple Orchard Estates Ltd | Real estate | 2018 |
| Apple PM Limited | Real estate | 2025 |
| Apple Tomato Pear and Peach Limited | Arts & recreation | 2021 |
| Apple Vehicles Ltd | Wholesale & retail | 2018 |
| Applecade Limited | Health & social care | 2024 |
| Applepine Limited | Health & social care | 2014 |
| Applepine Property Ltd | Real estate | 2025 |
| Appleshoes Ltd | Wholesale & retail | 2021 |
| Applewest Limited | Health & social care | 2011 |
| Applewood Consultancy Limited | Professional & scientific | 2012 |
| Applewood Development (Southwest) Ltd | Real estate | 2023 |
| Applewood PM Ltd | Real estate | 2019 |
| Appleyard Farm Ltd | Agriculture & fishing | 2017 |
| Application Data Limited | Information & communication | 2018 |
| Application Resource Management Limited | Information & communication | 2019 |
| Applied Business Resources Ltd | Information & communication | 2007 |
| Applied Perspective Limited | Information & communication | 2013 |
| Applied Psychology Limited | Health & social care | 2008 |
| Applied Success Limited | Information & communication | 2019 |
| Applied Torque Ltd | Construction | 2009 |
| Applied Torque Systems Limited | Construction | 2001 |
| Appnity Ltd | Information & communication | 2026 |
| Appoint Personnel Limited | Administrative & support | 2001 |
| Appolon LLP | | 2024 |
| Apprentices for Business Limited | Administrative & support | 2011 |
| Apprenticeship Learning Solutions Limited | Education | 2001 |
| Approach Biotech Corporation Limited | Professional & scientific | 2010 |
| Approved Powder Coating Limited | Manufacturing | 2019 |
| Approx PC | | 2018 |
| Appspring Studio Ltd | Manufacturing | 2024 |
| Appvalanche Digital Ltd | Information & communication | 2026 |
| Appventure Limited | Information & communication | 2025 |
| April Avenue Ltd | Information & communication | 2020 |
| April Interiors Limited | Construction | 2003 |
| APS (Advanced Plumbing Solutions) Limited | Construction | 2009 |
| APS Building Services and Maintenance Limited | Construction | 2015 |
| APS PVT Ltd | Real estate | 2024 |
| Apsara Cateing Ltd | Wholesale & retail | 2022 |
| Apsara Holding Group Ltd | Financial services | 2022 |
| Apscap Ltd | Information & communication | 2020 |
| Apsg Limited | Wholesale & retail | 2021 |
| APT Building & Maintenance Ltd | Construction | 2018 |
| APT Management Limited | Information & communication | 1991 |
| Aptacare Limited | Health & social care | 2022 |
| Apulian Street Food Ltd | Hospitality | 2023 |
| Apus Energy Limited | Energy | 2014 |
| APW Productions Ltd | Arts & recreation | 2022 |
| APX Coaching Ltd | Health & social care | 2022 |
| APX Holdings Ltd | Financial services | 2025 |
| APZ Electronics Ltd | Other services | 2019 |
| AQA (Cardiff) Limited | Water & waste | 2012 |
| Aqil Goods Limited | Wholesale & retail | 2025 |
| Aqsashakeel Trading Limited | Wholesale & retail | 2025 |
| Aqua Alarm UK Ltd | Professional & scientific | 2021 |
| Aqua Development Services Ltd | Construction | 2018 |
| Aqua Fashions Apparel Ltd | Wholesale & retail | 2012 |
| Aqua House Trading Limited | Wholesale & retail | 2025 |
| Aqua Plumbing and Heating Specialists Ltd | Construction | 2016 |
| Aqua Terra Consultants Ltd | Professional & scientific | 2024 |
| Aquagrow Ltd | Wholesale & retail | 2025 |
| Aqualure Ltd | Wholesale & retail | 2026 |
| Aquamacs (UK) Ltd | Agriculture & fishing | 2011 |
| Aquamacs T/A Aquamacs Ltd | Health & social care | 2013 |
| Aquamarin Ltd | Wholesale & retail | 2025 |
| Aquamarine Shipping Consultants Limited | Administrative & support | 1999 |
| Aquaped Limited | Professional & scientific | 2010 |
| Aquaplanter Ltd | Wholesale & retail | 2022 |
| Aquarius Counselling Ltd | Health & social care | 2019 |
| Aquarius I.S. Consultancy Limited | Information & communication | 1998 |