| SKR Studios & Apartments Limited | Real estate | 2017 |
| Sky Herts Ltd | Hospitality | 2024 |
| Skygenapps Limited | Information & communication | 2015 |
| SLE Creative Limited | Information & communication | 2017 |
| SLR Projects Ltd | Administrative & support | 2025 |
| Small World Ideas Ltd | Wholesale & retail | 2022 |
| Smart Onion Limited | Information & communication | 2024 |
| Smart Spray Repairs Ltd | Wholesale & retail | 2022 |
| Smart Surv Limited | Households | 2020 |
| SME Electrical Engineering Services Limited | Construction | 2022 |
| SMJ Engineering Services Ltd | Professional & scientific | 2021 |
| Smrtwaste Ltd | Water & waste | 2023 |
| Snipsharp Ltd | Wholesale & retail | 2024 |
| Snow Property Ventures Ltd | Real estate | 2024 |
| Snowbility Ltd | Education | 2015 |
| SO Leadbetter Ltd | Financial services | 2023 |
| SOC Plumbing & Heating Ltd | Construction | 2026 |
| Soccer Projects Ltd | Administrative & support | 2025 |
| Softwash Stan Ltd | Administrative & support | 2022 |
| Soil Consultants Limited | Administrative & support | 1984 |
| Solario Racing LLP | | 2010 |
| Solmax Limited | Administrative & support | 2026 |
| Sonare Systems Limited | Professional & scientific | 2026 |
| Sound House London Ltd | Arts & recreation | 2022 |
| Sovest Limited | Real estate | 2015 |
| Sparks Industries Ltd | Information & communication | 2023 |
| Spawning Point Ltd | Information & communication | 2024 |
| SPC (2021) Limited | Hospitality | 2021 |
| Specialist Alloy Services Ltd | Wholesale & retail | 2026 |
| Speciality Promotions Limited | Other services | 2013 |
| Specstimate Limited | Information & communication | 2017 |
| Speech Club Ltd | Health & social care | 2021 |
| Speedy Van Care Ltd | Wholesale & retail | 2025 |
| Spellbound Systems Limited | Professional & scientific | 1990 |
| Spencer & Mack Property Solutions Ltd | Real estate | 2021 |
| Sphere Works Limited | Professional & scientific | 2026 |
| Splosh Events Limited | Administrative & support | 2018 |
| Sportsplay Network Ltd | Information & communication | 2025 |
| Spring View Developments Ltd | Construction | 2024 |
| Sprint Door Systems Limited | Manufacturing | 2014 |
| Sprint Systems Group Limited | Financial services | 2026 |
| Square Carpentry and Construction Ltd | Manufacturing | 2017 |
| SR Cloud Solutions Ltd | Information & communication | 2016 |
| SRC Moto UK Ltd | Wholesale & retail | 2021 |
| SRT Trading Limited | Education | 2011 |
| ST Giles Flooring Ltd | Construction | 2017 |
| ST John's Berkhamsted Limited | Professional & scientific | 2020 |
| ST Mary's Place Northchurch Residents Company Limited | Households | 2002 |
| ST Mary's Pre-School (Northchurch) Ltd | Education | 2018 |
| ST Risk Consulting Ltd | Financial services | 2018 |
| ST. John's Well Court NO. 2 Residents Association Limited | Households | 1989 |
| ST. John's Well Court Residents Association Limited(The) | Households | 1981 |
| Staff Wanted Limited | Administrative & support | 2023 |
| Staffing Innovations Ltd | Administrative & support | 2025 |
| Star Self-Storage Centre Ltd | Extraterritorial | 2022 |
| Star Self-Storage Limited | Extraterritorial | 2022 |
| Star Transporter Ltd | Transport & logistics | 2024 |
| Stargira Advisors Ltd | Financial services | 2025 |
| Startups & Tune UPS Ltd | Professional & scientific | 2026 |
| State Machine Systems Ltd | Information & communication | 2013 |
| STATION10 Limited | Information & communication | 2011 |
| Stax Enterprises Ltd | Professional & scientific | 2026 |
| Steeples Holdings Ltd | Real estate | 2026 |
| Stello Talent Ltd | Administrative & support | 2022 |
| Stephenson Davenport Structural Associates Limited | Professional & scientific | 2014 |
| Sterikan Limited | Wholesale & retail | 2012 |
| Stewkley Management Company Limited | Households | 2024 |
| Stickle Brick Video Limited | Information & communication | 2011 |
| Stonelong Limited | Households | 1994 |
| Stonewave Development Ltd | Construction | 2025 |
| Strategic EA and Event Services Ltd | Professional & scientific | 2019 |
| Stratsmith Ltd | Professional & scientific | 2024 |
| Streamline Web Solutions Limited | Information & communication | 1998 |
| Streater Limited | Financial services | 2018 |
| Stridely Limited | Administrative & support | 2026 |
| Strike Talent Management Limited | Administrative & support | 2023 |
| Stripy TIE Limited | Professional & scientific | 2011 |
| Studham Construction Ltd | Construction | 2023 |
| Studio 136 Architects Limited | Professional & scientific | 2000 |
| Studio 4424 Ltd | Information & communication | 2024 |
| Studio Allen Ltd | Professional & scientific | 2019 |
| Success Matters Coaching Ltd | Health & social care | 2021 |
| Suite Assets Ltd | Real estate | 2021 |
| Summerling Flooring Ltd | Wholesale & retail | 2025 |
| Sun Photographic Bureau Limited | Professional & scientific | 1966 |
| Sundorbon Spice Ltd | Hospitality | 2025 |
| Sunnyside Rural Trust Limited | Education | 1991 |
| Superstorr Limited | Information & communication | 2012 |
| Supreme Party Gaming Van Ltd | Administrative & support | 2023 |
| Swart Holdings Ltd | Construction | 2020 |
| Swift Electrcal Services Ltd | Construction | 2024 |
| Swimming Mouse Solutions Limited | Arts & recreation | 2018 |
| Swipe Stack Ltd | Information & communication | 2012 |
| Synapse Media Technologies Ltd | Information & communication | 2020 |
| Syntasa UK Limited | Information & communication | 2018 |
| Synthesis Media Limited | Information & communication | 2011 |
| T D Higton Limited | Information & communication | 2022 |
| T Mitchell & Co Ltd | Administrative & support | 2011 |
| T Wells Consultancy Limited | Professional & scientific | 2013 |
| T. Williams Electrical Ltd | Construction | 2007 |