| Apex Print & Promotion Limited | Manufacturing | 2000 |
| Apex Properties Norfolk Ltd | Real estate | 2026 |
| Apex Revolution Health & Beauty Ltd | Manufacturing | 2023 |
| Apex Signs & Engraving Limited | Manufacturing | 1996 |
| Apex Signs Limited | Extraterritorial | 2012 |
| Apexx Services Limited | Construction | 2025 |
| API Capacitors Ltd | Manufacturing | 2006 |
| API Cognition Ltd | Extraterritorial | 2021 |
| API Engineering (O&G) Ltd | Professional & scientific | 2018 |
| API Fusion Technologies Ltd | Extraterritorial | 2018 |
| API Holdings Limited | Professional & scientific | 2014 |
| API Norwich Ltd | Professional & scientific | 2017 |
| API Stone Holdings Limited | Financial services | 2021 |
| API Stone Limited | Professional & scientific | 2010 |
| Apidx Limited | Professional & scientific | 2021 |
| Apitherapy Skincare Limited | Manufacturing | 2010 |
| APJ Holdings Limited | Financial services | 2017 |
| APK Building & Civil Engineering Ltd | Construction | 2020 |
| Apoaps Ltd | Professional & scientific | 2024 |
| Apogee Engineering Analysis Solutions Limited | Professional & scientific | 2008 |
| Apollo Composites Engineering Ltd | Professional & scientific | 2013 |
| Apollo Freight Logistics Ltd | Transport & logistics | 2025 |
| Apollo Health & Medical Limited | Health & social care | 2023 |
| Apollo Investment Management Ltd | Financial services | 2022 |
| Apollo Property Solutions Ltd | Construction | 2014 |
| Apollo's Garden Ltd | Manufacturing | 2025 |
| Apolloonepower Ltd | Professional & scientific | 2022 |
| Aporia Pictures Ltd | Information & communication | 2024 |
| Apostolos Kourtis Ltd | Professional & scientific | 2020 |
| App 101 Ltd | Professional & scientific | 2024 |
| App Advisory Plus Ltd | Professional & scientific | 2018 |
| App Tech Development Limited | Information & communication | 2016 |
| Apparatus Consulting Limited | Information & communication | 2012 |
| Appetite 4 Data Ltd | Professional & scientific | 2026 |
| Apple Box Films Limited | Administrative & support | 2008 |
| Apple Green Consultancy Ltd | Other services | 2017 |
| Apple Homecare Limited | Health & social care | 2015 |
| Apple Juice and Chocolate Ltd | Wholesale & retail | 2023 |
| Appleby Park Ltd | Real estate | 2022 |
| Applegarth Actuarial Services Limited | Professional & scientific | 2019 |
| Applegate Business Services Ltd | Professional & scientific | 2010 |
| Applegate Legal Services Ltd | Professional & scientific | 2023 |
| Applegate Property Holdings Ltd | Real estate | 2017 |
| Appleline Consulting & Marketing Solutions Ltd | Wholesale & retail | 2026 |
| Appleton's Bar & Restaurant Ltd | Hospitality | 2018 |
| Appletree Consultancy Limited | Professional & scientific | 2015 |
| Applexus Infotech Ltd | Information & communication | 2022 |
| Appliance Sales Limited | Other services | 2013 |
| Applied Genomics Ltd | Information & communication | 2014 |
| Applied Radiologic Limited | Health & social care | 2020 |
| Applied Studios Limited | Information & communication | 2009 |
| Appreciating Classics Ltd | Wholesale & retail | 2013 |
| Appswit Limited | Information & communication | 2017 |
| Appygrove Ltd | Information & communication | 2026 |
| Apraco Limited | Other services | 2025 |
| Aprhjr Limited | Financial services | 2024 |
| APS 2020 Limited | Real estate | 2020 |
| APS Care Ltd | Health & social care | 2002 |
| APS Care Trading Ltd | Administrative & support | 2017 |
| APS FH Ltd | Real estate | 2021 |
| APS Health Limited | Health & social care | 2006 |
| APS Leisure Upholstery Ltd | Other services | 2016 |
| APS Plastic Surgery Ltd | Health & social care | 2018 |
| APS SC Ltd | Real estate | 2021 |
| APS Telecom Solutions Ltd | Wholesale & retail | 2026 |
| Apsis Limited | Information & communication | 1996 |
| Apsl Group Limited | Construction | 2021 |
| Apsley Court Residents Association Limited | Households | 1977 |
| Aptsa Property Ltd | Real estate | 2020 |
| APY Productions Ltd | Arts & recreation | 2014 |
| AQ24 Ltd | Hospitality | 2024 |
| AQA Telecom Limited | Information & communication | 2014 |
| AQB Group Limited | Other services | 2024 |
| AQM International Ltd | Wholesale & retail | 2007 |
| Aqua Environmental Commissioning Ltd | Water & waste | 2023 |
| Aqua Pars Limited | Wholesale & retail | 2023 |
| Aqua VEG Ltd | Agriculture & fishing | 2023 |
| Aqua-Bell Limited | Extraterritorial | 1971 |
| Aqua-Dri Damp & Condensation Ltd | Construction | 2018 |
| Aqualush Limited | Wholesale & retail | 2016 |
| Aquamaintenance & Services Ltd | Administrative & support | 2022 |
| Aquanautia Limited | Professional & scientific | 2018 |
| Aquanique Plumbing Limited | Construction | 2024 |
| Aquapure Filtration Systems Ltd | Manufacturing | 2025 |
| Aquarate Limited | Administrative & support | 2017 |
| Aquarius Associates Limited | Professional & scientific | 1998 |
| Aquarius Healthcare Ltd | Health & social care | 2014 |
| Aquasola Ltd | Manufacturing | 2011 |
| Aquaterra Energy (Holdings) Limited | Professional & scientific | 2015 |
| Aquaterra Energy Group Limited | Financial services | 2017 |
| Aquaterra Energy Limited | Manufacturing | 2005 |
| Aquatherm Heating Limited | Construction | 2018 |
| Aquatic Complex Ltd | Extraterritorial | 2022 |
| Aquavate Safety Solutions Ltd | Information & communication | 2025 |
| Aqueduto | Public administration | 2015 |
| Aquillah Care Limited | Health & social care | 2014 |
| Aquisita Developments Limited | Construction | 2016 |
| Aquisita Legal Limited | Professional & scientific | 2025 |
| Aquisita Limited | Real estate | 2020 |
| Aquisita Property Holdings Limited | Real estate | 2017 |