| Sparrows Hill Livery Limited | Agriculture & fishing | 1997 |
| SPB Advisory Ltd | Wholesale & retail | 2024 |
| Specialised Shading Solutions Limited | Wholesale & retail | 2019 |
| Specialist Small Animal Surgery Services (Ssass) Ltd | Professional & scientific | 2015 |
| Spencer Planning Limited | Professional & scientific | 2024 |
| Spencer Road LLP | | 2008 |
| Spencer Road Membership Limited | Administrative & support | 2022 |
| SPIRIT1 Limited | Administrative & support | 2005 |
| Spirito Limited | Wholesale & retail | 2018 |
| Splinterpoint Ltd | Professional & scientific | 2024 |
| Spooly Products Limited | Wholesale & retail | 2018 |
| Sport in Balance Limited | Health & social care | 2023 |
| Sport Next Door Ltd | Wholesale & retail | 2024 |
| Sportvalue Limited | Arts & recreation | 2023 |
| Spotless Ltd | Administrative & support | 2021 |
| Spotlight Construction Limited | Construction | 2025 |
| Spring Public Relations Limited | Professional & scientific | 2015 |
| Springwell Projects Limited | Construction | 2017 |
| Springwell Stud Farm Ltd | Wholesale & retail | 2023 |
| Spruce and Bloom Limited | Administrative & support | 2012 |
| SPS Food and Wine Ltd | Wholesale & retail | 2021 |
| Sqreye Limited | Administrative & support | 2022 |
| Squire & Co. Executive Search Limited | Administrative & support | 2016 |
| SR Events (Design & Management) Limited | Administrative & support | 2012 |
| SRN Developments Limited | Construction | 2015 |
| SRS Dwellings Limited | Real estate | 2020 |
| SSF SPV Limited | Professional & scientific | 2019 |
| ST Edmunds Lane Management Limited | Construction | 2014 |
| ST Edmunds Meadow Management Company Limited | Households | 2023 |
| ST Lawrence Road Limited | Real estate | 2018 |
| ST Michaels Mews Ltd | Households | 2015 |
| ST. Thomas More Catholic Primary School | Education | 2011 |
| Stalker Strategy Limited | Professional & scientific | 2013 |
| Standen Manor Ltd | Professional & scientific | 2022 |
| Stansted House Limited | Wholesale & retail | 2011 |
| Stansted House Management Limited | Real estate | 2013 |
| Stansted Property Limited | Real estate | 2012 |
| Stansted Youth Club CIC | Other services | 2024 |
| Starseed Nexus Ltd | Professional & scientific | 2025 |
| Staymark Auto Plates Ltd | Manufacturing | 2012 |
| Steadlodge Limited | Wholesale & retail | 2001 |
| Steak House Royston Ltd | Hospitality | 2026 |
| Steele Dixon Accounting Limited | Administrative & support | 2000 |
| Steering Group Media Limited | Professional & scientific | 2023 |
| Stem Union Ltd | Wholesale & retail | 2025 |
| Stephen James Trichology Limited | Other services | 2023 |
| Stepper Investments Ltd | Real estate | 2024 |
| Sterling BEE Ltd | Wholesale & retail | 2016 |
| Steve Cross DOT BIZ Limited | Information & communication | 2014 |
| Steve LEE Design Consulting Limited | Professional & scientific | 2016 |
| Steve Parrish LLP | | 2025 |
| Stevenage Road Limited | Administrative & support | 2022 |
| Stickpin Limited | Wholesale & retail | 1999 |
| Still Nature Ltd | Real estate | 2026 |
| Sting Performing Arts Limited | Arts & recreation | 2021 |
| Stoneham Enterprise Ltd | Information & communication | 2007 |
| Storm Media Consulting Limited | Administrative & support | 2024 |
| Stort Consulting Ltd | Administrative & support | 2016 |
| Strategem Partners Ltd | Administrative & support | 2025 |
| Straticode Limited | Information & communication | 2025 |
| Strength in Sync Ltd | Education | 2025 |
| Strettington PV Ltd | Energy | 2014 |
| Stuart M Page Limited | Wholesale & retail | 2019 |
| Stuart Sharpless Design Limited | Professional & scientific | 2025 |
| Student Heaven Properties Ltd | Real estate | 2006 |
| Studio Evergreen Ltd | Information & communication | 2024 |
| Studio Gibberd Limited | Administrative & support | 2021 |
| Studio Meeson Ltd | Arts & recreation | 2008 |
| Styleplan Electrical Ltd | Construction | 2022 |
| Subsea Consulting Services Ltd | Professional & scientific | 2016 |
| Succeeder Limited | Professional & scientific | 2018 |
| Such & Such Limited | Wholesale & retail | 2013 |
| Sulman Creative Ltd | Information & communication | 2025 |
| Summerhill Standard Limited | Professional & scientific | 2021 |
| Sun Court (Management Company) Limited | Households | 2013 |
| Sun Generation (UK) Limited | Wholesale & retail | 2021 |
| Sun Generation Limited | Wholesale & retail | 2008 |
| Sun N Aqua Ltd | Hospitality | 2017 |
| Supercapacitor Materials Ltd | Manufacturing | 2016 |
| Superdielectrics Automotive Ltd | Professional & scientific | 2019 |
| Superdielectrics Autonomous Flying Vehicles Ltd | Professional & scientific | 2019 |
| Superdielectrics Electric Aircraft Ltd | Professional & scientific | 2019 |
| Superdielectrics Electric Bicycles Ltd | Professional & scientific | 2019 |
| Superdielectrics Electric Household Products Ltd | Professional & scientific | 2019 |
| Superdielectrics Electric Industrial Products Ltd | Professional & scientific | 2019 |
| Superdielectrics Electric Ships Ltd | Professional & scientific | 2019 |
| Superdielectrics Electric Trains Ltd | Professional & scientific | 2019 |
| Superdielectrics Grid Power Management Ltd | Professional & scientific | 2019 |
| Superdielectrics Group PLC | Financial services | 2021 |
| Superdielectrics Ltd | Professional & scientific | 2013 |
| Superdielectrics Mobile Electronics Ltd | Professional & scientific | 2019 |
| Superdielectrics Motorsport Ltd | Professional & scientific | 2019 |
| Superdielectrics Rapid Refuelling Ltd | Professional & scientific | 2019 |
| Superdielectrics Renewable Energy Storage Ltd | Energy | 2019 |
| Superdielectrics Research Ltd | Financial services | 2021 |
| Superdielectrics Supercap Ltd | Financial services | 2021 |
| Superdielectrics Vertical Farming Ltd | Professional & scientific | 2019 |
| Supporting Business Limited | Administrative & support | 2024 |
| Supreme Sanding Ltd | Construction | 2020 |
| Sure Store (UK) Limited | Real estate | 2014 |