| APN Construction Consultants Limited | Professional & scientific | 2023 |
| Apochi Haulage Limited | Transport & logistics | 2014 |
| Apogee Promotions Ltd | Arts & recreation | 2018 |
| Apohtams Ltd | Information & communication | 2017 |
| Apollo Health Consulting Limited | Professional & scientific | 2023 |
| Apollo Healthcare Analytics Ltd | Information & communication | 2025 |
| Apollo Island Investments Ltd | Real estate | 2010 |
| Apostille Solutions Ltd | Professional & scientific | 2022 |
| App Composites Ltd | Manufacturing | 2026 |
| Appara Technologies Limited | Wholesale & retail | 2023 |
| Appex Group Limited | Transport & logistics | 2017 |
| Appledown Properties Limited | Construction | 1991 |
| Applegarth Accounting Services Limited | Professional & scientific | 2005 |
| Applevertex Ltd | Wholesale & retail | 2026 |
| Appliance Direct (Morecambe) Limited | Wholesale & retail | 2002 |
| Appliance Repair Services Ltd | Other services | 2022 |
| Applicita Holdings Ltd | Financial services | 2021 |
| Applied Component Technology Limited | Manufacturing | 2012 |
| Applied Perception Ltd | Information & communication | 2025 |
| Applied Systems Integration Limited | Professional & scientific | 2000 |
| Appload Limited | Information & communication | 2012 |
| Appropriate Design Solutions Ltd | Professional & scientific | 2003 |
| Apps Logica Ltd | Information & communication | 2013 |
| Appstack X Ltd | Information & communication | 2025 |
| Appteq Limited | Information & communication | 2014 |
| APR Contracts Ltd | Construction | 2014 |
| APR Property Renovation and Management Ltd | Construction | 2026 |
| Apricity Play Therapy Ltd | Health & social care | 2025 |
| Apricot Consulting Ltd | Professional & scientific | 2023 |
| Apricot Services Ltd | Construction | 2026 |
| Apricus Advisory Ltd | Professional & scientific | 2023 |
| April Recruitment Limited | Administrative & support | 2019 |
| Apsam Consulting Ltd | Professional & scientific | 2026 |
| Apsrt Limited | Real estate | 2024 |
| APT Global Solutions Ltd | Information & communication | 2018 |
| Aptitech Limited | Construction | 1988 |
| Aptsyssolutions Ltd | Information & communication | 2024 |
| Aqbey Express Ltd | Transport & logistics | 2024 |
| Aqir Ltd | Hospitality | 2021 |
| Aqua Clean Services Limited | Administrative & support | 2018 |
| Aqua GAS Protocol AC Ltd | Construction | 2023 |
| Aqua GAS Protocol Ltd | Construction | 2013 |
| Aqua Parcs MK Limited | Arts & recreation | 2025 |
| Aqua Parcs Stevenage Limited | Arts & recreation | 2020 |
| Aquaden Housing Solutions Community Interest Company | Real estate | 2024 |
| Aquarius Music Limited | Other services | 1970 |
| Aquatech Irrigation Systems Limited | Administrative & support | 2017 |
| Aquatic Passions Ltd | Agriculture & fishing | 2019 |
| Aquavitaevodka Limited | Wholesale & retail | 2018 |
| Aquazoom Ltd | Manufacturing | 2018 |
| Aqube Solutions Limited | Information & communication | 2015 |
| Aquila Leisure Limited | Arts & recreation | 2009 |
| Aquila Nera Ltd | Wholesale & retail | 2024 |
| Aquios Labs Ltd | Manufacturing | 2022 |
| Aqureshi Educational Center Limited | Education | 2021 |
| AR Collezione Ltd | Information & communication | 2025 |
| AR Construction Group Ltd | Construction | 2026 |
| AR Renewable Energy Ltd | Wholesale & retail | 2026 |
| AR Rental Ltd | Wholesale & retail | 2019 |
| AR Security Solutions Ltd | Information & communication | 2023 |
| AR Windows Ltd | Construction | 2023 |
| Ar-Razzaq Foods Ltd | Hospitality | 2025 |
| AR4S Consulting Limited | Transport & logistics | 2024 |
| ARA Iseda Limited | Construction | 2025 |
| ARA Project Services Limited | Administrative & support | 2019 |
| Araa IT Services Ltd | Information & communication | 2022 |
| Araba Property Investment Ltd | Real estate | 2019 |
| Aradela Limited | Hospitality | 2023 |
| Aram Private Limited | Information & communication | 2015 |
| Aramas Trading Ltd | Wholesale & retail | 2021 |
| Aramco Group Ltd | Professional & scientific | 2026 |
| Arany Limited | Real estate | 2025 |
| Arapsys Limited | Information & communication | 2010 |
| Aras Caterers and Hospitality Solutions Ltd | Hospitality | 2014 |
| Aratrans Limited | Transport & logistics | 2016 |
| Arazak Services Ltd | Transport & logistics | 2018 |
| Arbilink Ltd | Wholesale & retail | 2025 |
| Arbor Technology (UK) Ltd | Information & communication | 1994 |
| ARC Arboricultural Solutions Limited | Administrative & support | 2019 |
| ARC Ddlonuk, Limited | Real estate | 2015 |
| ARC Exotics Ltd | Agriculture & fishing | 2019 |
| ARC HR Solutions Limited | Administrative & support | 2020 |
| ARC Hybrid Ltd | Education | 2026 |
| ARC Runclub Ltd | Education | 2026 |
| Arca Labs Ltd | Information & communication | 2026 |
| Arcana MK Ltd | Other services | 2017 |
| Arcane Cloud Services Ltd | Information & communication | 2021 |
| Arcane Investments Limited | Financial services | 2017 |
| ARCARS4U Ltd | Wholesale & retail | 2021 |
| Arceio Limited | Financial services | 2024 |
| Arch and Lens Limited | Information & communication | 2025 |
| Arch UK Consult Ltd | Other services | 2021 |
| ARCH5IVE Ltd | Manufacturing | 2026 |
| Archaeologica Limited | Professional & scientific | 1997 |
| Archangels Recruitment Limited | Health & social care | 2016 |
| Archea Spaces Ltd | Construction | 2020 |
| Archer-Hemsworth Consulting Limited | Professional & scientific | 2014 |
| Archetype Strategy Limited | Professional & scientific | 2016 |
| Archibold Property Holdings Limited | Real estate | 2015 |
| Archie.Pi Ltd | Financial services | 2023 |