| 08863636 Limited | Other services | 2014 |
| 11 Glebe Road Didcot Limited | Households | 2013 |
| 152 Elgin Avenue Limited | Households | 1987 |
| 1ST Financial Direction Limited | Extraterritorial | 2008 |
| 2ABCD Conway Road Limited | Other services | 2007 |
| 30 ST Mary`S Street Management Limited | Real estate | 2006 |
| 321DIVE Limited | Administrative & support | 2007 |
| 36 ST Marys Management Company Limited | Households | 2003 |
| 3C Industries Ltd | Real estate | 2026 |
| 3SIXTY Flooring Limited | Construction | 2009 |
| 3Y&JK Ltd | Real estate | 2022 |
| A Bientot Ltd | Information & communication | 2004 |
| A Bober Ltd | Transport & logistics | 2018 |
| A FEW Miles South Ltd | Information & communication | 2023 |
| A Gallery Ltd | Extraterritorial | 2014 |
| A J Prior Plumbing and Heating Ltd | Construction | 2019 |
| A&A Garden Sevices Ltd | Construction | 2021 |
| A&M Bookkeeping Services LLP | | 2022 |
| A.A Bains Property Ltd | Real estate | 2025 |
| A.C. Lester & SON Limited | Transport & logistics | 1963 |
| A.J Takeway Ltd | Hospitality | 2023 |
| A.J.Hawkins Limited | Real estate | 1936 |
| A.N. Technology Limited | Manufacturing | 1987 |
| AA Morgan Accounting and Bookkeeping Ltd | Professional & scientific | 2025 |
| Abingdon Scanning Limited | Administrative & support | 2015 |
| Abpod Investments Limited | Real estate | 2024 |
| Academy Analytics Limited | Real estate | 2013 |
| ACG Automation Engineering Limited | Professional & scientific | 2011 |
| ACUMEN7 Limited | Other services | 2003 |
| ACV Limited | Administrative & support | 2017 |
| AD Medical Air Assist Ltd | Health & social care | 2019 |
| ADA Jusic Illustration Limited | Professional & scientific | 2015 |
| Adaptdementia Ltd | Health & social care | 2017 |
| ADR Carpentry Limited | Manufacturing | 2013 |
| Adumbration Arts Ltd | Arts & recreation | 2020 |
| Advisemethod Limited | Households | 1991 |
| AE & DH Jenkins Limited | Financial services | 2021 |
| AFP Security Limited | Other services | 2022 |
| Afraponix Ltd | Financial services | 2020 |
| Ag-Fixings Ltd | Wholesale & retail | 2018 |
| Agentantics Ltd | Information & communication | 2025 |
| Agentic Autonomy Ltd | Information & communication | 2025 |
| AGM Construction and Groundworks Ltd. | Construction | 2018 |
| Ahota Limited | Professional & scientific | 2024 |
| AHS Corporate Ltd | Construction | 2023 |
| AI Btob Marketing Ltd | Information & communication | 2023 |
| Ai-Cog Ltd | Information & communication | 2023 |
| AIG Limited | Arts & recreation | 1995 |
| AIQ Consulting Limited | Professional & scientific | 2013 |
| Airspaces Events Limited | Extraterritorial | 2020 |
| AJT Bizdev Consulting Limited | Professional & scientific | 2015 |
| AJW Asset Management Ltd | Financial services | 2018 |
| AJW Dental & Aesthetic Ltd | Health & social care | 2022 |
| AK Residential Investments Limited | Real estate | 2021 |
| Akay Cars Limited | Transport & logistics | 2025 |
| Alan Clark Consulting Ltd | Information & communication | 2022 |
| Albry Printing Company Limited | Manufacturing | 1987 |
| Alex Cresswell Planning Consultancy Ltd | Professional & scientific | 2024 |
| Alexander Advertising (International) Limited | Professional & scientific | 1970 |
| Alexander Interiors Limited | Wholesale & retail | 2008 |
| Alexander Scientific Maintenance Limited | Professional & scientific | 2008 |
| Alfamoja Limited | Administrative & support | 2022 |
| Alice House Creates Ltd | Arts & recreation | 2024 |
| Aligned Growth Capital LLP | | 2024 |
| ALL About Kidz N20 Limited | Health & social care | 2021 |
| ALL Sorts of Handyman Services Ltd | Other services | 2018 |
| Allcloud Networks Limited | Information & communication | 2009 |
| Allum's of Oxon Limited | Extraterritorial | 2022 |
| Allure Beauty Lounge Limited | Other services | 2025 |
| Ally Wines Ltd | Wholesale & retail | 2020 |
| ALM Geophysics Limited | Administrative & support | 2013 |
| Alpha Care Ambulance Service Limited | Health & social care | 2002 |
| Alpha PHI Limited | Transport & logistics | 2022 |
| ALPN24 Ltd | Wholesale & retail | 2026 |
| Alumedia Ltd | Information & communication | 2015 |
| Alwin Mechanical Solutions Ltd | Construction | 2018 |
| Amct Properties Ltd | Real estate | 2025 |
| Americano Limited | Real estate | 1990 |
| Amt-Sybex Limited | Information & communication | 1995 |
| Amwell Springs Brewery Company Limited | Manufacturing | 2017 |
| Anderson & Jarvis Engineering Co. Limited | Professional & scientific | 1960 |
| Anderson Law LLP | | 2011 |
| Andrew Lord Furniture Limited | Manufacturing | 2015 |
| Andrew Pearmund Architectural Design and Construction Limited | Construction | 2007 |
| Andy Walton & Co Oxford Accountant Ltd | Professional & scientific | 2010 |
| Ango Ltd | Professional & scientific | 2008 |
| Anna's Alchemy Ltd | Administrative & support | 2026 |
| Annets Enterprises Limited | Manufacturing | 2010 |
| Anvil Moth Ltd | Administrative & support | 2025 |
| AOC Web Solutions Limited | Information & communication | 2010 |
| Apex Housing & Renovation Limited | Real estate | 2021 |
| APL Scaffolding Limited | Construction | 2017 |
| Apple Building Property Solutions Ltd | Construction | 2021 |
| Aprtd Ltd | Professional & scientific | 2022 |
| Aquateck Systems Ltd | Manufacturing | 2025 |
| Aquatools Hygiene Limited | Manufacturing | 2024 |
| Aquaware Systems Limited | Professional & scientific | 1994 |
| Aquila Communications Limited | Information & communication | 2002 |
| Arbor-Nova (TT Transplanters) Limited | Administrative & support | 2009 |
| ARC Planning Associates Limited | Professional & scientific | 2021 |