| Amphiform UK Ltd | Professional & scientific | 2026 |
| Amplify Intelligence Limited | Information & communication | 2016 |
| AMR Publishing Limited | Professional & scientific | 1996 |
| Amrahs Projects Ltd | Construction | 2025 |
| Amro Class Limited | Administrative & support | 2026 |
| AMT Consulting Ltd | Professional & scientific | 2022 |
| AN & SN Partners LLP | | 2025 |
| An-Nafe PVT Ltd | Wholesale & retail | 2024 |
| Anakata Wind Power Resources Ltd | Professional & scientific | 2012 |
| Anando Limited | Hospitality | 2019 |
| Anchor Financial Solutions Ltd | Financial services | 2025 |
| Anchor Investment Europe LLP | | 2011 |
| Anchor Management Europe Ltd | Real estate | 2011 |
| Anconia Limited | Information & communication | 2010 |
| AND MEN Ltd | Other services | 2017 |
| AND SO Design Ltd | Professional & scientific | 2024 |
| Anderson & Hamilton Limited | Financial services | 2017 |
| Anderson Business Media Limited | Professional & scientific | 2011 |
| Anderson IT Consulting Limited | Information & communication | 2008 |
| Andreas Coffee Iffley Road Ltd | Hospitality | 2025 |
| Andrew JOB Plumbing & Heating Limited | Construction | 2007 |
| Andrew John Roscoe Limited | Health & social care | 2007 |
| Andrew Munns Tree Surgery Ltd | Agriculture & fishing | 2020 |
| Andrews Electrical & Energy Services Limited | Construction | 2025 |
| Andromeda Software Solutions Ltd | Administrative & support | 2015 |
| Andy Layug Limited | Health & social care | 2018 |
| Andycars Taxis ( Cheltenham ) Limited | Transport & logistics | 2018 |
| Anesbarber Ltd | Other services | 2026 |
| Angel N1 Limited | Real estate | 2007 |
| Angel Sharp Media Limited | Professional & scientific | 2014 |
| Angela Munro CBT Ltd | Health & social care | 2011 |
| Angevins House Management Company Limited | Households | 2011 |
| Angly's Trading & Investment Ltd | Financial services | 2024 |
| Angridthai Limited | Hospitality | 2025 |
| Angry Bear Machinery Ltd | Professional & scientific | 2009 |
| Angus Frazer Limited | Professional & scientific | 2022 |
| Anidam Market Place Limited | Wholesale & retail | 2025 |
| Anigma Housing Limited | Real estate | 2014 |
| Animals at Home (Oxford) Ltd | Other services | 2015 |
| Animals in Science - Education Trust | Education | 2009 |
| Animarum Properties Limited | Construction | 2013 |
| Anjost Investment Advisory Ltd | Professional & scientific | 2019 |
| Ann's Munchies Limited | Hospitality | 2003 |
| Anna's Guest House Ltd | Hospitality | 2023 |
| Annabellejoycbt Ltd | Health & social care | 2024 |
| Anne Donald Limited | Professional & scientific | 2018 |
| Anne Veck Limited | Other services | 2010 |
| Annie Sloan Interiors Ltd | Manufacturing | 2010 |
| Antalia Traditional Turkish Barber Ltd | Other services | 2024 |
| Antares Homes Ltd | Real estate | 2023 |
| Antares Productions Ltd | Arts & recreation | 2023 |
| Antep Cafe 27 Ltd | Hospitality | 2025 |
| Anthony Antonis Investments Limited | Other services | 2016 |
| Anthony Berendt Consulting Limited | Professional & scientific | 2018 |
| Anthony Larcombe Limited | Health & social care | 2014 |
| Anthony Ward Partnership Limited | Professional & scientific | 1999 |
| Antigone Properties Ltd | Real estate | 2017 |
| Antonia James Limited | Health & social care | 2025 |
| Antonia Lloyd Limited | Information & communication | 2008 |
| Antonia Logistics 2025 Ltd | Transport & logistics | 2025 |
| Antonis IT Solutions Ltd | Information & communication | 2015 |
| Antony Turner Limited | Professional & scientific | 2006 |
| Antorise Ltd | Wholesale & retail | 2026 |
| Antrups Limited | Administrative & support | 2012 |
| ANY Group Ltd | Information & communication | 2021 |
| Anyvision Group Ltd | Professional & scientific | 2024 |
| AON Auto Consultant Limited | Professional & scientific | 2010 |
| AP Damp Solutions Ltd | Construction | 2025 |
| AP Lims and Regulatory Consulting Limited | Professional & scientific | 2026 |
| APA Consultants Limited | Professional & scientific | 2009 |
| APE Movements Limited | Transport & logistics | 2025 |
| Apel Holdings Limited | Real estate | 1972 |
| Aperio DP Ltd | Information & communication | 2026 |
| Apex 18 Limited | Information & communication | 2024 |
| Apex BN Ltd | Hospitality | 2019 |
| Apex Direct Limited | Wholesale & retail | 2020 |
| APH Construction Limited | Construction | 2017 |
| Aphis Security Limited | Administrative & support | 2019 |
| API Photographic Services Limited | Professional & scientific | 2003 |
| APL Gillows Lettings Limited | Hospitality | 2018 |
| APL Gillows Limited | Construction | 2013 |
| APL Reading Lettings Limited | Hospitality | 2017 |
| APL Reading Limited | Hospitality | 2016 |
| Apogee Bioautomation Ltd | Professional & scientific | 2025 |
| Apollo Attire Ltd | Wholesale & retail | 2026 |
| Apollo Trade Window Store Limited | Wholesale & retail | 2007 |
| Aporia Ltd | Manufacturing | 2018 |
| App Accommodation Ltd | Hospitality | 2017 |
| Appa Mount Pleasant Limited | Professional & scientific | 2003 |
| Appa Property Ltd | Real estate | 2005 |
| Appaccomm Ltd | Hospitality | 2017 |
| Appleinter.Net UK Limited | Professional & scientific | 2000 |
| Appleton Enterprises Limited | Professional & scientific | 2011 |
| Applewood Garden Services Limited | Administrative & support | 2012 |
| Applied Actuarial Systems Limited | Financial services | 2011 |
| Applied Spatial Research Ltd | Information & communication | 2019 |
| Appn Limited | Wholesale & retail | 2022 |
| Appollo Solutions Limited | Real estate | 2004 |
| Approved Building Control Services Limited | Other services | 2014 |
| Apptapas Ltd | Hospitality | 2024 |