| Sky-High Electronics Limited | Information & communication | 1990 |
| Skyline Joinery Ltd | Manufacturing | 2016 |
| Skyraker Ltd | Construction | 2018 |
| SLB Decor Ltd | Professional & scientific | 2025 |
| SLP Communication Services Limited | Information & communication | 2022 |
| SM Heath Holdings Ltd | Financial services | 2025 |
| SM66 Trading Limited | Real estate | 2014 |
| Smart Aero Technology Ltd | Professional & scientific | 2011 |
| Smata Limited | Professional & scientific | 2015 |
| SMC Painting Contractors Ltd | Construction | 2007 |
| Snipptec UK Ltd | Manufacturing | 2015 |
| Society for French Studies | Professional & scientific | 1999 |
| Soft Auto Limited | Wholesale & retail | 2023 |
| Sojourn Solutions UK Limited | Administrative & support | 2015 |
| Soltribe Limited | Information & communication | 2026 |
| Sortd App Limited | Extraterritorial | 2022 |
| Sound Control Services Ltd | Manufacturing | 2025 |
| Sourced Oxford Ltd | Real estate | 2020 |
| South Birmingham and Solihull Property Management Ltd | Financial services | 2025 |
| Southfield Primary School | Education | 2012 |
| SP Wilf Ltd | Professional & scientific | 2024 |
| Spanner in the Workx Ltd | Information & communication | 2024 |
| Sparrowhawk Building Ltd | Construction | 2018 |
| Spectrumforchange Ltd | Health & social care | 2024 |
| Speech Therapy Systems Ltd | Health & social care | 2022 |
| Splitways Clothing Ltd | Wholesale & retail | 2025 |
| Spring Valley Consulting Ltd | Professional & scientific | 2020 |
| SSP Advisory Services Ltd | Information & communication | 2025 |
| ST Andrew's Cross Ltd | Information & communication | 2016 |
| STAG-3D Ltd | Manufacturing | 2025 |
| Stanstead Plant Limited | Administrative & support | 2026 |
| Stella Health Solutions Limited | Health & social care | 2017 |
| Stellar Facades Ltd | Construction | 2024 |
| Stengel Optical Limited | Wholesale & retail | 2021 |
| Stepping Stones Pre-School (Brackley) | Education | 2006 |
| Sterling Shopping Ltd | Wholesale & retail | 2009 |
| Steve Ring Heating and Plumbing Ltd | Construction | 2019 |
| Steven Physique Ltd | Wholesale & retail | 2021 |
| Stevens of Boston Ltd | Wholesale & retail | 2024 |
| Stewart Energy (Insulation) Limited | Manufacturing | 1980 |
| Stone & Mortar Developments Ltd | Real estate | 2024 |
| Stone House Daycare & Grooming Ltd | Other services | 2023 |
| Stonebank Ironcraft Limited | Extraterritorial | 2020 |
| Stonebridge Developments MK Limited | Real estate | 2025 |
| Stoneclove Property Management Limited | Administrative & support | 2006 |
| Stoves N Flues Ltd | Wholesale & retail | 2022 |
| Stowaway Productions Limited | Other services | 2024 |
| Strat 1 Property Investment Ltd | Real estate | 2024 |
| Strata Bidco Limited | Financial services | 2024 |
| Strata Creative Communications Ltd | Professional & scientific | 1997 |
| Strata Creative Holdings Limited | Financial services | 2017 |
| Strata Holdco Limited | Financial services | 2024 |
| Strata Midco Limited | Financial services | 2024 |
| Strategic Housing Solutions Limited | Professional & scientific | 2022 |
| Stronghold Building Services Ltd | Construction | 2018 |
| Studio Armell Ltd | Manufacturing | 2024 |
| Studio Armell Stage Ltd | Professional & scientific | 2024 |
| Studio Soeur Limited | Information & communication | 2019 |
| Sudoku Steel Ltd | Construction | 2021 |
| Summit Carpentry & Construction Ltd | Construction | 2017 |
| Sun Agricultural Services Limited | Agriculture & fishing | 2011 |
| Sunrise Surveys Ltd | Professional & scientific | 2021 |
| Supaskip Limited | Extraterritorial | 2002 |
| Superskip Limited | Extraterritorial | 2002 |
| Supersound UK Limited | Real estate | 2010 |
| Support Services Direct Limited | Professional & scientific | 2003 |
| Sure Footcare Ltd | Health & social care | 2019 |
| Suzyreidrentals Limited | Real estate | 2024 |
| SVE Ventures Ltd | Wholesale & retail | 2025 |
| Sweetieverse Ltd | Manufacturing | 2020 |
| Swift & Son's Roofing Ltd | Construction | 2023 |
| Swift Contract Solutions Ltd | Information & communication | 2025 |
| Sylvan Shack Limited | Hospitality | 2018 |
| Syresham Sports & Social Club Limited | Hospitality | 2020 |
| Systematic Insulation Services Ltd | Construction | 2022 |
| T & C Construction Services (Northampton) Limited | Construction | 2013 |
| T & S Threadgold Limited | Water & waste | 2002 |
| T Abernethy and Partners Limited | Agriculture & fishing | 2014 |
| T G K Electrical Ltd | Construction | 2019 |
| T W I Pubs Limited | Administrative & support | 2014 |
| T&C Brickwork Ltd | Construction | 2024 |
| T&C Group Holdings Ltd | Construction | 2024 |
| T&C Property & Development Ltd | Real estate | 2021 |
| T3DHQ Ltd | Professional & scientific | 2017 |
| Taffync Investments Limited | Administrative & support | 2020 |
| TAG Investments Limited | Real estate | 1999 |
| Tailored Timber Ltd | Construction | 2026 |
| Talent Equation Consulting Ltd | Professional & scientific | 2023 |
| Talent Equation Holdings Limited | Financial services | 2024 |
| Talrasha Ltd | Information & communication | 2025 |
| Tanis Developments Ltd | Information & communication | 2021 |
| Tanks a LOT Ltd | Administrative & support | 2002 |
| Tanso Design Ltd | Manufacturing | 2021 |
| Taylor Anaesthesia Limited | Health & social care | 2018 |
| Taylor Plant & Construction Limited | Construction | 2009 |
| Taylor Vets Holdings Limited | Professional & scientific | 2026 |
| Taylored Tenancies Limited | Real estate | 2017 |
| TB Property Studio Limited | Real estate | 2026 |
| TBG 1 (Towcester) Ltd | Other services | 2025 |
| Team Extreme Limited | Arts & recreation | 2003 |