| Sonogram LDN Ltd | Information & communication | 2017 |
| Sonoscape Medical Corp Limited | Professional & scientific | 2009 |
| Soul Spa Ltd. | Professional & scientific | 2013 |
| SOUND4VISION Ltd | Information & communication | 2007 |
| South Bucks Tree Surgeons Ltd | Agriculture & fishing | 2009 |
| Sovereign Copy Ltd | Extraterritorial | 2023 |
| Specialised Latex Services Limited | Manufacturing | 1973 |
| Spice Lounge 1 Limited | Real estate | 2008 |
| Spice of India (Oxon) Ltd | Hospitality | 2024 |
| Spink Steam Cleaning Ltd | Administrative & support | 2020 |
| Spirit Rise Ltd | Real estate | 2025 |
| Springfield Finance and Accounting Services Limited | Professional & scientific | 2014 |
| Spruced-Up Limited | Administrative & support | 2003 |
| Spybey Digital Ltd | Professional & scientific | 2021 |
| Squidge Inc Ltd | Administrative & support | 2009 |
| SS Enterprise Limited | Professional & scientific | 1999 |
| SSA Property Holdings Ltd | Real estate | 2021 |
| Stagg Property Holdings Ltd | Real estate | 2023 |
| Standapart Limited | Wholesale & retail | 2014 |
| Stargage Limited | Information & communication | 2005 |
| Startup Logistics Limited | Transport & logistics | 2020 |
| Staycool Refrigeration Services Limited | Manufacturing | 2014 |
| Stenn Inns Ltd. | Hospitality | 2021 |
| Step UP Bucks Limited | Administrative & support | 2023 |
| Stereomet Limited | Other services | 2012 |
| Steve Watmore Limited | Financial services | 2016 |
| Stevo's Servo Limited | Wholesale & retail | 2007 |
| Stirrup Computing Services Limited | Professional & scientific | 2016 |
| Stone Ecology Limited | Information & communication | 2026 |
| Stonebridge Holdings Limited | Professional & scientific | 2004 |
| Stonebridge UK Limited | Manufacturing | 1961 |
| Storage Media Limited | Information & communication | 2025 |
| Strategic Direction Performance Management Limited | Professional & scientific | 2005 |
| Strathmore UK Investments Limited | Professional & scientific | 2014 |
| Stratisal Ltd | Professional & scientific | 2025 |
| Stratton Chase Ltd | Construction | 1980 |
| Stuart Groves Furniture Limited | Manufacturing | 2002 |
| Studio Cheval Ltd | Professional & scientific | 2021 |
| Studio Creme Ltd | Professional & scientific | 2015 |
| Studio George Ltd | Professional & scientific | 2020 |
| Studio Griff Ltd | Administrative & support | 2017 |
| Studio LM Ltd | Professional & scientific | 2018 |
| Studio RGL Partnership LLP | | 2017 |
| Suepet Limited | Health & social care | 2019 |
| Sumby Care Limited | Health & social care | 2021 |
| Sumbystore Limited | Wholesale & retail | 2022 |
| Summit Coaching Limited | Other services | 2023 |
| Sunglow Group UK Limited | Administrative & support | 2024 |
| Sunset Village Veterinary Ltd | Professional & scientific | 2026 |
| Super Razor Ltd | Other services | 2021 |
| Supernova Tech Limited | Professional & scientific | 2014 |
| Supersan Ltd | Professional & scientific | 2023 |
| Supersede Ltd | Information & communication | 2013 |
| Supreme PH Ltd | Transport & logistics | 2021 |
| Surman Softly Properties Limited | Real estate | 2022 |
| Surve Limited | Real estate | 2014 |
| Swan Place (Tetsworth) Management Company Limited | Real estate | 2014 |
| Swannybrook Solar Limited | Energy | 2026 |
| Sweet Yourself Ltd. | Wholesale & retail | 2020 |
| Swellsound Technical Services Limited | Arts & recreation | 2021 |
| SWG Investments Ltd | Real estate | 2023 |
| Syderek Holdings Limited | Real estate | 2021 |
| Syderek Limited | Professional & scientific | 2020 |
| Sygensys Ltd | Other services | 2011 |
| Sylo Beyond HR. Limited | Administrative & support | 2010 |
| Szokz Ltd | Wholesale & retail | 2021 |
| T J Rose Design & Build Limited | Construction | 2008 |
| T&L Holdco Limited | Administrative & support | 2024 |
| T.C.E. Wheller Holdings Limited | Professional & scientific | 2024 |
| T.J. Young PM Services Ltd | Professional & scientific | 2022 |
| Tactical Direct Mailing Limited | Administrative & support | 2006 |
| Tactical Fulfilment Solutions Ltd | Administrative & support | 2005 |
| Tais Sirote Limited | Professional & scientific | 2021 |
| Take Note Book Limited | Wholesale & retail | 2017 |
| Tally UP Limited | Professional & scientific | 2012 |
| Tamefire Limited | Construction | 1986 |
| Targa Holdings Ltd | Financial services | 2024 |
| Tata Couriers Ltd | Transport & logistics | 2026 |
| Tate & Clayburn Ltd | Extraterritorial | 2020 |
| TCS Engineering Ltd | Professional & scientific | 2014 |
| TDM Estate Management Limited | Real estate | 2025 |
| Techelec Installations Ltd | Construction | 2007 |
| Technology Transfer Innovation Ltd | Professional & scientific | 2017 |
| Teknik Ltd | Professional & scientific | 2025 |
| Telecoms Advisor Limited | Information & communication | 2010 |
| Telemachus Limited | | 1977 |
| Telematicus Services Limited | Information & communication | 2020 |
| Telling Stories Limited | Extraterritorial | 2012 |
| TEN Mile Menu Limited | Wholesale & retail | 2012 |
| Tetsworth Estate Limited | Real estate | 2004 |
| Thame and London Limited | Administrative & support | 2012 |
| Thame Aromas Ltd | Wholesale & retail | 2022 |
| Thame Bathroom Solutions Ltd | Construction | 2019 |
| Thame Builders Limited | Construction | 2019 |
| Thame Chiropractic Clinic Ltd | Health & social care | 2021 |
| Thame Chop Ltd | Other services | 2025 |
| Thame Clinic Holdings Ltd | Real estate | 2024 |
| Thame Community Pride CIC | Hospitality | 2024 |
| Thame Cycles Limited | Wholesale & retail | 2021 |
| Thame Food Festival C.I.C. | Professional & scientific | 2012 |