| Square Foods Ltd | Hospitality | 2013 |
| Square Mile Associates Limited | Professional & scientific | 2011 |
| Square One Homes Limited | Real estate | 2022 |
| Squarey Ltd | Real estate | 2021 |
| Squib Media Limited | Professional & scientific | 2013 |
| Squid Content Ltd | Professional & scientific | 2024 |
| SR Flight Services Limited | Transport & logistics | 2013 |
| SR Kavin Ltd | Wholesale & retail | 2023 |
| Sr&G Holdings Ltd | Financial services | 2026 |
| SRM Software Ltd | Information & communication | 2025 |
| Sroka Property Services Ltd | Construction | 2016 |
| SS Beauty (Witney) Ltd | Other services | 2025 |
| SS FIC Ltd | Financial services | 2026 |
| SS Hair Ltd | Other services | 2025 |
| SS Plastering Ltd | Construction | 2024 |
| SS Selling Limited | Administrative & support | 2024 |
| Ssassy Property Ltd | Construction | 2017 |
| Ssassy Springfield Ltd | Construction | 2018 |
| SSH Civils Limited | Administrative & support | 2013 |
| ST Martin Holdings Limited | Financial services | 2019 |
| STA Management Services Ltd | Real estate | 2026 |
| Stacey and Mason LLP | | 2018 |
| Stachsystems Ltd | Construction | 2010 |
| Staff Members Ltd | Administrative & support | 2020 |
| Stancaster Holdings Ltd | Financial services | 2026 |
| Standlake Limited | Construction | 2021 |
| Standlake MOT & Repair Centre Limited | Wholesale & retail | 2025 |
| Standlake Vehicle Services Limited | Wholesale & retail | 2005 |
| Stanford Services Limited | Wholesale & retail | 2024 |
| Stanma Ltd | Extraterritorial | 2017 |
| Stanton Flooring Ltd | Construction | 2022 |
| Stanton House Enterprises Limited | Wholesale & retail | 2003 |
| Start Online Ltd | Professional & scientific | 2020 |
| Station Field Kidlington Ltd | Households | 2016 |
| Stavi's Way Ltd | Wholesale & retail | 2024 |
| Stay Farrier Ltd | Hospitality | 2021 |
| Stealthcampervans Ltd | Manufacturing | 2022 |
| Steed Group Ltd | Transport & logistics | 2022 |
| Stephen Hatton Limited | Construction | 2008 |
| Stephen Hodge Associates Limited | Professional & scientific | 2004 |
| Sterling Clinics Oxford Limited | Health & social care | 2016 |
| Sterling Renovations Ltd | Construction | 2022 |
| Steve Austen Flooring Limited | Construction | 2013 |
| Steve Benson Holdings Limited | Financial services | 2025 |
| Steve Fallows Game Farm Limited | Agriculture & fishing | 2011 |
| Steven J Sensecall Limited | Other services | 2012 |
| Still and Wild Limited | Other services | 2025 |
| Still Hunting Media Ltd | Professional & scientific | 2026 |
| Stockton Construction Consulting Ltd | Construction | 2025 |
| Stone City Consulting Ltd | Wholesale & retail | 2015 |
| Stone Gables Management Company Limited | Households | 1992 |
| Stonecopper Limited | Construction | 2010 |
| Stonecroft (Cornwall) Ltd | Real estate | 2020 |
| Stonesfield Garage LLP | | 2015 |
| Stoney Wood Holdings Limited | Financial services | 2021 |
| Storm Guard Roofing Limited | Construction | 2023 |
| Storm Guard Roofing Solutions Ltd | Construction | 2025 |
| Storm Internet Limited | Information & communication | 2004 |
| Storm Motors (Oxon) Ltd | Wholesale & retail | 2022 |
| Story Ninety-Four Ltd | Information & communication | 2019 |
| Storytelling Schools Ltd | Education | 2015 |
| Stow Gardens Ltd | Hospitality | 2023 |
| Strachan Medical Limited | Health & social care | 2020 |
| Strainge Investments Ltd | Real estate | 2020 |
| Strainge Stays Ltd | Hospitality | 2024 |
| Strategic Mentors Limited | Professional & scientific | 2010 |
| Strategic Proposals (ROJ) Ltd | Professional & scientific | 2009 |
| Stratfield Studios Limited | Education | 2018 |
| Stratzen Ltd | Administrative & support | 2021 |
| Stream Networks Limited | Information & communication | 2007 |
| Stream Technology and Mobile Ltd | Extraterritorial | 2020 |
| Striding Edge Advanced Engineering Limited | Professional & scientific | 2023 |
| Strike UX Ltd | Professional & scientific | 2018 |
| Stringer Properties Limited | Real estate | 2011 |
| Strivee Ltd | Wholesale & retail | 2020 |
| Strongbuild Properties Ltd | Real estate | 2021 |
| STS Trans Ltd | Construction | 2020 |
| Stuart Davis Roofing (Cotswold) Ltd | Construction | 2026 |
| Stuart Indge Carpentry Services Limited | Construction | 2012 |
| Stuart Young Training Ltd | Information & communication | 2024 |
| Studio Way (Borehamwood) Management Company Limited | Households | 1996 |
| Stylus Consulting Limited | Administrative & support | 2022 |
| Subairos Limited | Professional & scientific | 2024 |
| SUE Stockdale Limited | Professional & scientific | 2006 |
| Sumer Sorrel Residents Association Limited | Households | 2023 |
| Summit Trees Limited | Agriculture & fishing | 2020 |
| Sun Prime Land Property Ltd | Real estate | 2017 |
| Sundance Foods Ltd | Wholesale & retail | 2026 |
| Super S Properties Limited | Hospitality | 2025 |
| Superdogs Rescue CIC | Other services | 2024 |
| Supereight Studio Ltd | Information & communication | 2009 |
| Superyacht Partners Limited | Financial services | 2020 |
| Suppdrops Ltd | Extraterritorial | 2025 |
| Supportive Growth Limited | Administrative & support | 2024 |
| Suprr: Supporting Ukrainian Publishing Resilience and Recovery CIC | Information & communication | 2026 |
| Surge Technologies Ltd | Information & communication | 2025 |
| Surman & Horwood Funeral Services Limited | Other services | 2004 |
| Surmans Limited | Other services | 2004 |
| Sutherland Securities Limited | Financial services | 2014 |
| Suzanne's Ministries | Other services | 2006 |