| Aaron Foong Ltd | Other services | 2019 |
| AB & LB FIC Limited | Real estate | 2023 |
| AB FAB Properties Limited | Construction | 2008 |
| Abbey Farm Limited | Hospitality | 2025 |
| Abbey Roofing Contractors Limited | Construction | 1998 |
| Abbeyfields Residents Company Limited | Extraterritorial | 2001 |
| Abbott Diabetes Care Limited | Manufacturing | 1990 |
| Abelwood Limited | Manufacturing | 2019 |
| Aberhodge Limited | Real estate | 2021 |
| Abilitynexus Ltd | Other services | 2024 |
| Abingdon Gymnastics Club (Properties) Limited | Other services | 2023 |
| Abingdon Marina (Oxford) Limited | Transport & logistics | 2000 |
| Absaroka Consulting Limited | Information & communication | 2025 |
| Absolute Climate Solutions Ltd | Energy | 2016 |
| Absolutely Holdings Ltd | Professional & scientific | 2008 |
| ACB Management Services Ltd | Professional & scientific | 2025 |
| Access ALL Property Ltd | Extraterritorial | 2022 |
| Accident Solution Centre Limited | Wholesale & retail | 2006 |
| Accounts & Tax Sorted Ltd | Professional & scientific | 2023 |
| Ace Assets Holding Limited | Real estate | 2023 |
| Ace Productions Limited | Real estate | 2012 |
| ACH Plastering Ltd | Construction | 2015 |
| Achanak Limited | Hospitality | 2025 |
| Achc Ltd | Professional & scientific | 2020 |
| Ackerman & Niece Limited | Wholesale & retail | 2002 |
| ACL Computer Services Limited | Information & communication | 2003 |
| Acom Aviation Ltd | Information & communication | 2021 |
| Acre END Close Management Ltd | Households | 2022 |
| Acre Hill Garage Limited | Real estate | 2002 |
| Acre Mews Long Hanborough Limited | Households | 2020 |
| Acrona Engineering Limited | Manufacturing | 2001 |
| Adair's FBA Ltd | Wholesale & retail | 2023 |
| Adali Healthcare Ltd | Health & social care | 2015 |
| Adam's Mower Services Ltd | Manufacturing | 2019 |
| Adaptix Animal Care UK Limited | Extraterritorial | 2022 |
| Adaptix IDT UK Limited | Extraterritorial | 2022 |
| Adaptix Medical UK Limited | Extraterritorial | 2022 |
| Adaptix NDE UK Limited | Extraterritorial | 2022 |
| Addicus Property Ltd | Real estate | 2017 |
| Adept Graphics Limited | Manufacturing | 2015 |
| Adept Group Holdings Limited | Financial services | 2026 |
| Adgomo Limited | Information & communication | 2018 |
| ADH Limited | Wholesale & retail | 2023 |
| ADJ Golf Ltd | Wholesale & retail | 2021 |
| Admincare Solutions Ltd | Professional & scientific | 2024 |
| Admiral Developments (Abingdon) Ltd | Construction | 2018 |
| Admiral Property Management Ltd | Construction | 2018 |
| ADR Service & Repairs Limited | Wholesale & retail | 2005 |
| Adrian Foggett Limited | Professional & scientific | 2025 |
| Adrian Property Limited | Real estate | 2022 |
| Adriane Dias Interiors Ltd | Construction | 2019 |
| Adroit Staffing Limited | Administrative & support | 2023 |
| Advanta Digital Limited | Professional & scientific | 2026 |
| Advencha Ltd | Information & communication | 2025 |
| Advent Research Materials Limited | Wholesale & retail | 1988 |
| Adverti Digital Limited | Information & communication | 2021 |
| ADW Autos Ltd | Wholesale & retail | 2023 |
| Adyton Global Ltd | Real estate | 2015 |
| AE Financial Limited | Financial services | 2023 |
| Aegis Management Services Limited | Professional & scientific | 2003 |
| Aeia Ltd | Arts & recreation | 2025 |
| AEJ Consulting Engineers Ltd | Professional & scientific | 2025 |
| Aeon Labs Limited | Health & social care | 2026 |
| Aero Surface Design Ltd | Professional & scientific | 2024 |
| Aesop Arts and Society Limited | Health & social care | 2009 |
| Aesthetics by Amanda Jane Ltd | Other services | 2021 |
| AF Automation Ltd | Professional & scientific | 2023 |
| AG Rotor Support Ltd | Manufacturing | 2026 |
| Agency Digital Limited | Administrative & support | 2017 |
| Agent in One Ltd | Professional & scientific | 2024 |
| Agile Scaffolding Contractors Ltd | Construction | 2010 |
| Agnp Limited | Real estate | 2014 |
| Agri Sport Leisure Limited | Agriculture & fishing | 2004 |
| Agricompas Limited | Agriculture & fishing | 2016 |
| Agrivert Limited | Water & waste | 1994 |
| Agrivert Operations Limited | Other services | 2019 |
| Agrivert Renewables Limited | Financial services | 2018 |
| AH Projects (Oxford) Limited | Construction | 2022 |
| AH Windows (Oxford) Limited | Construction | 2025 |
| AI Cyber Solutions Ltd | Information & communication | 2023 |
| AI Search Labs Ltd | Information & communication | 2025 |
| Aikman Heating Limited | Construction | 2012 |
| Air Power Europe Limited | Transport & logistics | 2025 |
| AJ 4WD Outfitters Limited | Wholesale & retail | 2015 |
| AJ Catering (Oxfordshire) Limited | Hospitality | 2013 |
| AJ Prestige Travel Limited | Transport & logistics | 2026 |
| AJB Accountancy & Tax Ltd | Professional & scientific | 2021 |
| AJB Technical Services Limited | Professional & scientific | 2013 |
| AJC Medical Limited | Health & social care | 2017 |
| AJF Wills Ltd | Professional & scientific | 2024 |
| AK Autos Witney Ltd | Wholesale & retail | 2022 |
| AK Joinery Ltd | Manufacturing | 2005 |
| Akira's Tales Ltd | Agriculture & fishing | 2025 |
| Akoca Ltd | Professional & scientific | 2017 |
| Akrb Ltd | Professional & scientific | 2014 |
| Akyurek Limited | Hospitality | 2018 |
| Al-Modina Association West Oxfordshire | Administrative & support | 2013 |
| Alan Lever GAS Services Limited | Construction | 2002 |
| Alan Morgan Ltd | Professional & scientific | 2018 |
| ALB Flooring Ltd | Construction | 2010 |