| Antrobus (Boldmere) Limited | Health & social care | 2011 |
| Anvietech Consulting Limited | Information & communication | 2025 |
| AO Construction Services Ltd | Professional & scientific | 2020 |
| Aotd Ltd | Real estate | 2025 |
| AP & VP Ltd | Real estate | 2020 |
| AP Crossings Ltd | Administrative & support | 2023 |
| AP Nagar Limited | Administrative & support | 2023 |
| Apache Indian Music (A.I.M) Academy Ltd | Health & social care | 2015 |
| APC Boldmere Limited | Real estate | 2013 |
| Apex & Co. Cleaning and Maintenance Limited | Administrative & support | 2025 |
| Apex Biker Safety Ltd | Manufacturing | 2026 |
| Apex BLU Ltd | Professional & scientific | 2023 |
| Apex Delivery Services Ltd | Transport & logistics | 2021 |
| Apex Express Limited | Transport & logistics | 2024 |
| Apex Height Safety Limited | Construction | 2012 |
| Apex Prime Investments Ltd | Real estate | 2026 |
| Apex Private Finance Limited | Financial services | 2019 |
| Apex Sourcing Ltd | Professional & scientific | 2024 |
| Apex Surveying Solutions Ltd | Professional & scientific | 2024 |
| Apex Therapies Ltd | Health & social care | 2018 |
| APH Property Limited | Real estate | 2018 |
| Apocalypse Medical Limited | Health & social care | 2022 |
| Apollo Music Management Limited | Arts & recreation | 2017 |
| Apollo Property Lettings Ltd | Real estate | 2026 |
| Apollo Realty Ltd | Real estate | 2020 |
| Apothica Health Limited | Wholesale & retail | 2026 |
| Appcentric Ltd | Information & communication | 2013 |
| Apple Catcher Ltd | Professional & scientific | 2005 |
| Apple Gardens Management Company Limited | Households | 2018 |
| Appleton-Gate Fish Bar Ltd | Hospitality | 2024 |
| APPRENTICESHIPS4EDUCATION Ltd | Education | 2021 |
| Approved Land Limited | Real estate | 2019 |
| Appsta Limited | Information & communication | 2019 |
| Apres Aviation Limited | Extraterritorial | 2025 |
| Apres Furniture Limited | Wholesale & retail | 2008 |
| Apres Group Limited | Wholesale & retail | 2009 |
| Apres Interiors Limited | Extraterritorial | 2009 |
| APS Central Limited | Education | 2022 |
| Aptel Logistics Ltd | Transport & logistics | 2021 |
| Apto-Gen Limited | Manufacturing | 2019 |
| APX Automotive Ltd | Wholesale & retail | 2024 |
| Aquar Consultancy Ltd | Professional & scientific | 2021 |
| Aquascape Fish Imports Limited | Agriculture & fishing | 2003 |
| Aquila Roofing Limited | Construction | 2018 |
| AR Dreamz Ltd | Real estate | 2021 |
| AR Dubb Ltd | Health & social care | 2014 |
| Arako Limited | Health & social care | 2023 |
| Aran Properties (UK) Limited | Real estate | 2020 |
| Araya Louise Ltd | Hospitality | 2022 |
| Araybee Limited | Professional & scientific | 2007 |
| ARB Building Limited | Construction | 2019 |
| ARB Drive Limited | Households | 2022 |
| ARB20 Ltd | Construction | 2020 |
| ARC Building Design Ltd | Professional & scientific | 2004 |
| Archers Acres Ltd | Administrative & support | 2013 |
| Architectural Design Consultancy Limited | Professional & scientific | 2002 |
| Arctic 1 Developments Limited | Financial services | 2020 |
| Arden Architectural Limited | Wholesale & retail | 2009 |
| Arden House Developments Limited | Real estate | 2015 |
| Ardentia Care Limited | Health & social care | 2025 |
| Ardroe Investments Limited | Real estate | 2024 |
| Arena Printing Limited | Manufacturing | 2024 |
| Argo Healthcare Limited | Health & social care | 2015 |
| Argonaut Capital Ltd | Real estate | 2022 |
| Argyle Crest Limited | Professional & scientific | 2019 |
| Aric Accountants Ltd | Professional & scientific | 2012 |
| Aries Communications Limited | Information & communication | 2023 |
| Arimas RZ Ltd | Professional & scientific | 2025 |
| Arise Housing Group Ltd | Education | 2023 |
| Arista Restaurants Limited | Hospitality | 2013 |
| Arizac Limited | Real estate | 2025 |
| Arizona Multi-Media Limited | Information & communication | 2006 |
| Arjun Patel Ltd | Health & social care | 2025 |
| Arjun's Catering Ltd | Hospitality | 2026 |
| ARK Foundation | Information & communication | 2016 |
| ARK Media Productions Limited | Information & communication | 2009 |
| ARK Media Studios Limited | Real estate | 2023 |
| ARK Solutions Midlands Limited | Other services | 2024 |
| Arkaa Services Limited | Other services | 2010 |
| Arkere Limited | Health & social care | 2023 |
| ARL Parcels Limited | Transport & logistics | 2019 |
| Arlo Legal Ltd | Professional & scientific | 2025 |
| ARM Project Solutions Limited | Professional & scientific | 2013 |
| Arma Property Ltd | Real estate | 2017 |
| Armed Car Security Limited | Administrative & support | 2020 |
| Armfield Angling Ltd | Administrative & support | 2010 |
| Armitage (Funeral Directors) Limited | Extraterritorial | 1998 |
| Armscote Limited | Transport & logistics | 2018 |
| Aromaa Commodities Ltd | Extraterritorial | 2025 |
| Arotan Ltd | Real estate | 2025 |
| Arpino Food and B&B Ltd | Hospitality | 2026 |
| Arron Roofing Systems Limited | Construction | 2003 |
| Arsh Derma Ltd | Health & social care | 2025 |
| Arshu Properties Ltd | Real estate | 2017 |
| Arta Selly Oak Ltd | Administrative & support | 2018 |
| Artemis Talent Solutions Limited | Administrative & support | 2024 |
| Arthur Denyer Limited | Extraterritorial | 1945 |
| Arthur G. Whitehead (Westminster) Limited | Extraterritorial | 1937 |
| Arthur J. Nash Limited | Extraterritorial | 2012 |
| Artisan Construction (B'Ham) Limited | Construction | 2018 |