| Supergrass (UK) Limited | Wholesale & retail | 2000 |
| Superior Edge Ltd | Professional & scientific | 2026 |
| Supernova Pubs Ltd | Hospitality | 2024 |
| Superpal Limited | Wholesale & retail | 2019 |
| Superwolf Limited | Health & social care | 2010 |
| Support for the Sick Newborn and Their Parents | Health & social care | 2011 |
| Surevest Oxford Ltd | Real estate | 2025 |
| Surgex Medicolegal Limited | Professional & scientific | 2009 |
| Surgro Commercial Ltd | Information & communication | 2026 |
| Surman Agriculture Limited | Agriculture & fishing | 2017 |
| Surman Land Limited | Agriculture & fishing | 2024 |
| Surrey Hills Park Limited | Real estate | 2025 |
| Survival Instincts Ltd | Wholesale & retail | 2019 |
| Susan Liautaud & Associates Limited | Other services | 2012 |
| Sussex Self Store Limited | Real estate | 2019 |
| Sustainable Apparel Services Ltd | Information & communication | 2020 |
| Sustainable Investment Management Limited | Financial services | 2018 |
| Sustainable Investment Platform Limited | Extraterritorial | 2024 |
| Sustainable Refurbs Ltd | Construction | 2023 |
| Sustainable Wedding Alliance Ltd | Professional & scientific | 2020 |
| Sutton Kaizen Consulting Limited | Professional & scientific | 1999 |
| SVC Consultancy Ltd | Professional & scientific | 2016 |
| Sved Fernandez Limited | Information & communication | 2017 |
| Svetlo Ltd | Wholesale & retail | 2020 |
| Svlb Limited | Manufacturing | 2024 |
| Svmk Limited | Administrative & support | 2007 |
| SW Benham Limited | Health & social care | 2009 |
| Swale Technologies Limited | Wholesale & retail | 1990 |
| Swan Management Co. Ltd | Real estate | 2007 |
| Swan Noble Ltd | Administrative & support | 2014 |
| Swan Street Freehold Management Company Limited | Households | 2025 |
| Swanee River Investments | Financial services | 2017 |
| Swanee River Limited | Real estate | 2017 |
| Swanee River Residential Ltd | Real estate | 2025 |
| Sweet Center Limited | Hospitality | 2023 |
| Sweetcroft Homes Limited | Construction | 1972 |
| Swell Wold Farm LLP | | 2010 |
| Swift Wheel Services PVT. Ltd | Wholesale & retail | 2025 |
| Swiftbuyzone Limited | Wholesale & retail | 2025 |
| Swiftcraft Ltd | Wholesale & retail | 2025 |
| Swiftest Ltd | Information & communication | 2023 |
| Swiftrax Logistics Ltd | Transport & logistics | 2026 |
| Swim School of Oxfordshire Ltd | Arts & recreation | 2016 |
| Swindon Speedway 2013 Limited | Arts & recreation | 2013 |
| Swing Records Limited | Arts & recreation | 2010 |
| Swissstem Consulting Ltd | Information & communication | 2025 |
| Swista Ltd | Manufacturing | 2025 |
| SWJ Technology UK Limited | Professional & scientific | 2023 |
| Sword Food Limited | Hospitality | 2011 |
| Swordfish International Ltd | Professional & scientific | 2020 |
| SY777 Ltd | Transport & logistics | 2023 |
| Sya'Adah Aesthetic Limited | Other services | 2026 |
| Sycamore Online Business Management Ltd | Administrative & support | 2021 |
| Sycamore Property Limited | Real estate | 2024 |
| SYD Oxford Limited | Hospitality | 2005 |
| Sylogist (UK) Limited | Information & communication | 1998 |
| Sylva Consultancy Limited | Agriculture & fishing | 2009 |
| Sylva Trees Limited | Agriculture & fishing | 2009 |
| Sylvia House Freehold Limited | Extraterritorial | 2012 |
| Sylvia Sideris Consulting Limited | Professional & scientific | 2026 |
| Sylvie Zannier Literary Scouting Limited | Information & communication | 2013 |
| Symbyont UK Ltd | Wholesale & retail | 2019 |
| Synaptixbio Ltd | Professional & scientific | 2021 |
| Synchronicity Technology Services Ltd | Professional & scientific | 2011 |
| Synchronicity Technology Solutions Limited | Information & communication | 2011 |
| Synergistic Solutions Consultancy Limited | Professional & scientific | 2014 |
| Synergy (Mepr) Limited | Professional & scientific | 2025 |
| Synergy Global Consulting Ltd | Professional & scientific | 1999 |
| Synergy Global Group Limited | Financial services | 2020 |
| Synergy Nutrition Limited | Health & social care | 2016 |
| Synox Therapeutics UK Limited | Professional & scientific | 2021 |
| Synterra Ventures Limited | Financial services | 2025 |
| SYR Oxford Ltd | Real estate | 2025 |
| Syria the Glorious History Ltd | Professional & scientific | 2018 |
| Syrian Community Oxford and Oxfordshire Syrcox Ltd | Health & social care | 2020 |
| SYS8 Holding Limited | Energy | 2008 |
| System C Healthcare Limited | Information & communication | 1983 |
| Systematic Equity Partners Ltd | Information & communication | 2015 |
| Systematic Learning Limited | Education | 2014 |
| Systematic Review Consultants Ltd | Arts & recreation | 2016 |
| Systemic Link Consulting Ltd | Professional & scientific | 2022 |
| SYX Art Ltd | Professional & scientific | 2019 |
| Szymon Trans Limited | Transport & logistics | 2016 |
| T & F Trading Solutions Ltd | Wholesale & retail | 2023 |
| T & KJ Company Limited | Health & social care | 2022 |
| T & V Building and Construction Limited | Construction | 2021 |
| T 12 Ltd | Arts & recreation | 2002 |
| T Alabaster Construction Limited | Construction | 2010 |
| T J Hall & SON Limited | Wholesale & retail | 2006 |
| T Morrow Ltd | Information & communication | 2011 |
| T State Limited | Administrative & support | 2012 |
| T&H Property Construction (Oxford) Ltd | Extraterritorial | 2015 |
| T(Art) Productions C.I.C. | Arts & recreation | 2021 |
| T-Crown Holdings Ltd | Real estate | 2019 |
| T-Sharp Systems Limited | Information & communication | 2007 |
| T. Robins (Services) Limited | Real estate | 1976 |
| T.J.S Landscapes Limited | Administrative & support | 2023 |
| T113 Ltd | Health & social care | 2021 |
| T5 Interactive Limited | Information & communication | 2025 |
| TA Property Maintenance Oxford Ltd | Construction | 2025 |