| Spence's Property Limited | Real estate | 2024 |
| Spencer Higgins Limited | Real estate | 2025 |
| Spice and Sunshine Ltd | Manufacturing | 2025 |
| Spiers & Pond Limited | Professional & scientific | 2011 |
| Split Second Security Ltd | Administrative & support | 2026 |
| Spratley Bloom Ltd | Professional & scientific | 2024 |
| Springhill Construction Limited | Construction | 2018 |
| Sprite Song Interactive Ltd | Information & communication | 2022 |
| Spruce Ltd | Other services | 2020 |
| Squared-Apples Ltd. | Administrative & support | 2014 |
| Sreekrupa Life Sciences Ltd | Professional & scientific | 2026 |
| SRI Investments Ltd | Real estate | 2018 |
| SS Cleaning Ltd | Administrative & support | 2026 |
| SS Quality Resources Limited | Information & communication | 2015 |
| ST Helen Properties Limited | Professional & scientific | 2004 |
| ST Hughs Rise Management Company Limited | Real estate | 2011 |
| ST James Terrace Limited | Households | 2020 |
| ST Mary Fields Managements Limited | Households | 1987 |
| Stageflight Supplements Ltd | Wholesale & retail | 2024 |
| Stallard Smith Limited | Administrative & support | 2024 |
| State of Mind Limited | Wholesale & retail | 2010 |
| Status Computer Appointments (Maidstone) Limited | Administrative & support | 1979 |
| Stay Dench Limited | Wholesale & retail | 2009 |
| Steen's Property Enterprise Ltd | Real estate | 2023 |
| Stephanie Mills Finance Limited | Professional & scientific | 2019 |
| Steptoe Partnership LLP | | 2025 |
| Steve Payne Limited | Wholesale & retail | 2002 |
| Stevens Product Services Limited | Financial services | 2012 |
| Steventon Consultancy Limited | Professional & scientific | 2015 |
| Stiff and Trevillion Architects Limited | Professional & scientific | 2008 |
| Stiff Real Estate Limited | Real estate | 2025 |
| STO Consultancy Limited | Professional & scientific | 2015 |
| Stoja SP Ltd | Hospitality | 2025 |
| Stonade Limited | Manufacturing | 2023 |
| Stone House Land Limited | Real estate | 2005 |
| Stone Street Living Freehold Ltd | Real estate | 2025 |
| Stone Street Living Ltd | Real estate | 2024 |
| Stone Trees Estates Limited | Construction | 2013 |
| Stonehill Community Gardens | Health & social care | 2016 |
| Stones & Leigh Limited | Construction | 2026 |
| Story Engine Ltd | Information & communication | 2026 |
| Storynory Limited | Information & communication | 2005 |
| Storynory Publishing Limited | Arts & recreation | 2010 |
| Straconstruct Limited | Professional & scientific | 2006 |
| Strataic Ltd | Information & communication | 2024 |
| Strategic Proposals (BOH) Limited | Professional & scientific | 2018 |
| Strategy Activist Ltd. | Professional & scientific | 2015 |
| Strike Gold Trading Ltd | Wholesale & retail | 2024 |
| Stuart & Sons Building Services Limited | Construction | 2014 |
| Stubber Developments Limited | Real estate | 2025 |
| Studio High VIS Ltd | Arts & recreation | 2023 |
| Studio of US Limited | Administrative & support | 2024 |
| Studio Taylor Limited | Construction | 2025 |
| SUD Retail Ltd | Wholesale & retail | 2025 |
| Suemag Property Investments Limited | Real estate | 2020 |
| Suffolk International Equine Services Limited | Administrative & support | 2022 |
| Sugarbeat Music Ltd | Arts & recreation | 2017 |
| Sula Innovation Ltd | Professional & scientific | 2017 |
| Summit (Oxford) Limited | Professional & scientific | 2003 |
| Summit Therapeutics Limited | Professional & scientific | 2004 |
| Sunbeat Records Ltd | Arts & recreation | 2009 |
| Sunny Food House Ltd | Hospitality | 2025 |
| Sunnyhill Studios Limited | Arts & recreation | 2019 |
| Supa ANT Ltd | Manufacturing | 2020 |
| Super Sticky Squisho Limited | Arts & recreation | 1997 |
| Superflats Limited | Real estate | 2000 |
| Supermario.Works Ltd | Information & communication | 2026 |
| Suppliersupremeco Ltd | Wholesale & retail | 2025 |
| Support for Africa | Extraterritorial | 2000 |
| Sureheat Spares Ltd | Wholesale & retail | 2013 |
| Surface Innovations Limited | Professional & scientific | 2001 |
| Surge Information Technology Ltd | Information & communication | 2009 |
| Survivor Space CIC | Health & social care | 2025 |
| Survivor Space Oxfordshire Ltd | Other services | 2009 |
| Susie Spolander Education Consultancy Ltd | Education | 2016 |
| Sustainable Energy Environment Ltd | Agriculture & fishing | 2013 |
| Sustainable Lifestyles Ltd | Professional & scientific | 2017 |
| Sutton Brickwork Limited | Construction | 2015 |
| Svalbard Group Limited | Professional & scientific | 2026 |
| SVC Centric Ltd | Information & communication | 2022 |
| Swan Global Education LLP | | 2017 |
| Swift Labour Ltd | Construction | 2024 |
| Swinburne Management Limited | Real estate | 2023 |
| Swish Direct Limited | Manufacturing | 2016 |
| Swish IP Holdings Limited | Administrative & support | 2015 |
| Sylosis Limited | Administrative & support | 2013 |
| Sylus Pharmaceuticals Ltd | Health & social care | 2002 |
| Sylvatica Investments Ltd. | Real estate | 2013 |
| Sylvatica Trading Limited | Administrative & support | 2017 |
| Systemix Limited | Professional & scientific | 2020 |
| Systems Biology Laboratory UK C.I.C | Professional & scientific | 2004 |
| T & L Dean Properties Limited | Real estate | 2018 |
| T Nanomed Limited | Professional & scientific | 2025 |
| T Roberts Oral Health Ltd | Health & social care | 2024 |
| T S Carpentry and Building Services Ltd | Construction | 2019 |
| T T Jewellers Limited | Wholesale & retail | 2002 |
| T&S Orthotics Limited | Manufacturing | 2008 |
| T-Biotech Limited | Manufacturing | 2023 |
| T-Cypher BIO Holdings Limited | Professional & scientific | 2020 |
| T-Cypher BIO Limited | Professional & scientific | 2015 |