| SPRING86 Limited | Information & communication | 2025 |
| Springall Ltd | Professional & scientific | 2026 |
| SPW Legal Ltd | Professional & scientific | 2024 |
| Spyglass Solutions Ltd | Information & communication | 2005 |
| Squares Estate Agents Limited | Real estate | 2003 |
| SRI Consultancy Ltd | Professional & scientific | 2025 |
| Srii Property Investments Ltd | Real estate | 2024 |
| SRK Analytics Limited | Information & communication | 2013 |
| SRK Property Holdings Ltd | Real estate | 2019 |
| SRM Painting Ltd | Construction | 2023 |
| Ssat Ltd | Wholesale & retail | 2019 |
| Stable Court Brackley Residents Association Ltd | Households | 2003 |
| Stanley Rose Furniture Limited | Manufacturing | 2015 |
| Star Cars (Hornsea) Limited | Transport & logistics | 2005 |
| Startanew Ltd | Professional & scientific | 2023 |
| Starter Productions Limited | Information & communication | 2005 |
| Stay UP Late Marketing and Consulting Ltd | Other services | 2018 |
| Steeple Cycles Ltd | Wholesale & retail | 2022 |
| Steeple Industries Limited | Wholesale & retail | 1991 |
| Steeple Investments Limited | Wholesale & retail | 2023 |
| Stokke UK Limited | Administrative & support | 1997 |
| Storm Video Productions Ltd | Information & communication | 2012 |
| Stowe Castle Film Productions Limited | Information & communication | 2005 |
| Stowe Castle Films Limited | Information & communication | 2003 |
| Stowe China Limited | Education | 2016 |
| Stowe Enterprises Limited | Education | 1978 |
| Stowe Limited | Professional & scientific | 2014 |
| Stowe School Developments Limited | Education | 2011 |
| Stowe School Limited | Education | 1923 |
| Strategic Transformation Services Limited | Information & communication | 2025 |
| Stratford Tools Limited | Manufacturing | 1966 |
| Strattons Property Limited | Construction | 2014 |
| Strekoza Limited | Education | 2018 |
| Stress-Space Ltd. | Professional & scientific | 2017 |
| Stripey Limited | Information & communication | 2016 |
| Strobe Electrics Limited | Construction | 2017 |
| Strongarm Home Renovations Limited | Construction | 2022 |
| Strongarm Property Solutions Limited | Construction | 2014 |
| Structor Consulting Limited | Professional & scientific | 2022 |
| Studio Direct Productions Ltd | Information & communication | 2012 |
| Studiocorko Ltd | Professional & scientific | 2015 |
| Stygal-Watson Consulting Associates Ltd | Professional & scientific | 2015 |
| Successful Coaching Ltd | Professional & scientific | 2023 |
| Sugar Nails Limited | Other services | 2021 |
| Suitors Menswear Limited | Other services | 2018 |
| Sukraya Properties Ltd | Real estate | 2024 |
| Sumisura Limited | Extraterritorial | 2011 |
| Sunlit Software Ltd | Information & communication | 2024 |
| Sunrise Asset Management Ltd. | Administrative & support | 1993 |
| Sunshine Lofts Limited | Construction | 2007 |
| Super Ears UK Ltd | Wholesale & retail | 2022 |
| Superior Paint Works Ltd | Construction | 2019 |
| Superport Ltd | Information & communication | 2024 |
| Surma Vegetables Ltd | Wholesale & retail | 2026 |
| Svs-Tech Info Limited | Transport & logistics | 2024 |
| SW Construction & Joinery Limited | Information & communication | 2015 |
| Swan Centre Management Company Limited | Real estate | 2006 |
| Swan Consulting Group Ltd | Information & communication | 2023 |
| Swan DRY Cleaners Ltd | Wholesale & retail | 2025 |
| Sweet Dreams Lingerie Limited | Wholesale & retail | 2003 |
| SWG Polymer Services Limited | Other services | 2005 |
| Swgpolymers Ltd | Other services | 2018 |
| Swindon Stoke Limited | Transport & logistics | 2019 |
| Swish Investments Limited | Other services | 2024 |
| Systemap Limited | Information & communication | 2003 |
| T & C Audit Services Ltd | Professional & scientific | 2025 |
| T & T Glass Ltd | Construction | 2015 |
| T H Jelf LLP | | 2013 |
| T&L Realty Holdings Ltd | Real estate | 2025 |
| T. King Associates Limited | Professional & scientific | 2001 |
| T. T. Topco Ltd | Financial services | 2026 |
| T.H.E. Clinical Consultancy Limited | Professional & scientific | 2006 |
| T.J.P. Autos Ltd | Wholesale & retail | 2025 |
| T2TM Ltd | Construction | 2025 |
| Tabernus Peram Limited | Wholesale & retail | 2012 |
| Taffe's Maintenance Ltd | Construction | 2023 |
| TAM International Limited | Manufacturing | 2008 |
| Tambolita Ltd | Professional & scientific | 2025 |
| Tanzanite Global Ltd | Water & waste | 2020 |
| Tap-In Ltd | Wholesale & retail | 2025 |
| Tautology Consulting Ltd | Other services | 2017 |
| Tautology Ltd | Other services | 2024 |
| Tavern Bar Millport Limited | Hospitality | 2019 |
| Taylan Lewis Property Investments Ltd | Real estate | 2025 |
| Taylor Dart Physiotherapy Ltd | Health & social care | 2024 |
| Taylor Family Property Ltd | Real estate | 2023 |
| Taylor Made Treatments Limited | Other services | 2008 |
| TC Calibration Limited | Professional & scientific | 2013 |
| TCB House Rentals Limited | Real estate | 2023 |
| TCS Biosciences Limited | Manufacturing | 1987 |
| TDI Design and Production Ltd | Manufacturing | 2014 |
| TDT Developments Limited | Construction | 2022 |
| Teamwork Solutions Ltd | Administrative & support | 2017 |
| Tearle & Carver Limited | Professional & scientific | 2010 |
| Temple and Co Carpentry Ltd | Construction | 2021 |
| TEN Days Consulting Limited | Information & communication | 2022 |
| Tenacity Clothing Ltd | Wholesale & retail | 2026 |
| Terrington Investments | Financial services | 2026 |
| Testingeye Consultancy Ltd | Information & communication | 2021 |
| TFG Builders Limited | Construction | 2002 |