| Simpkins Jewellers Limited | Wholesale & retail | 2005 |
| Simple Taxis Ltd | Transport & logistics | 2025 |
| Simply Stainless Limited | Wholesale & retail | 1997 |
| Simpson Human Resources Ltd | Administrative & support | 2025 |
| Simtas and SON Ltd | Other services | 2019 |
| Sisu Cryo Limited | Professional & scientific | 2024 |
| SJ Melios Limited | Professional & scientific | 2022 |
| Sjas Heritage Crime Prevention Consultancy Limited | Professional & scientific | 2023 |
| SJL Estates Limited | Real estate | 2022 |
| SJM Advisory Limited | Professional & scientific | 2024 |
| Skyvolt Limited | Administrative & support | 2020 |
| Slaf Limited | Extraterritorial | 2020 |
| SM & KP Developments Limited | Construction | 2024 |
| Smart Angling Group Ltd | Agriculture & fishing | 2021 |
| Smart East Hand Car Wash Ltd | Other services | 2017 |
| Smart Garage Services Limited | Information & communication | 2025 |
| Smart Utilities Ltd | Information & communication | 2021 |
| Smartlife Services Community Interest Company | Professional & scientific | 2026 |
| SMG Group Holdings Ltd | Financial services | 2021 |
| Smit Growth Limited | Real estate | 2023 |
| Smith & Donovan Limited | Construction | 2013 |
| Smith and Tyers Limited | Manufacturing | 2009 |
| Smiths Letting Limited | Real estate | 2025 |
| Smitten TOO - Coggeshall Limited | Wholesale & retail | 2019 |
| SMM Strategic Projects LLP | | 2012 |
| Smooth Vehicle Logistics Limited | Wholesale & retail | 2023 |
| SMT Associates (Essex) Limited | Professional & scientific | 1989 |
| Snootbeest Limited | Information & communication | 2021 |
| Soka Care Ltd | Health & social care | 2026 |
| Soka Enterprises Ltd. | Real estate | 2017 |
| Solar Montage Team UK Ltd | Construction | 2021 |
| Solid State Tech Ltd | Wholesale & retail | 2018 |
| Somerset Internet Services Limited | Professional & scientific | 1995 |
| SON Traders Limited | Construction | 2017 |
| Sophia Warner Limited | Arts & recreation | 2011 |
| Sound & Vision (Sensory) Community Interest Company | Professional & scientific | 2021 |
| South Eastern Removals Limited | Transport & logistics | 2023 |
| South Glamorgan Internet Services Limited | Professional & scientific | 1995 |
| South Yorkshire Internet Services Limited | Professional & scientific | 1995 |
| Southway Capital Limited | Real estate | 2023 |
| Sove Ltd | Wholesale & retail | 2025 |
| Sovereign Kingdom Ltd | Information & communication | 2022 |
| Sowatin Consulting UK Limited | Information & communication | 2013 |
| Sowman Plumbing and Heating Limited | Construction | 2003 |
| Space Corporation Limited | Real estate | 2022 |
| Sparks Fabrication Ltd | Manufacturing | 2024 |
| Sparks Works Ltd | Construction | 2018 |
| Speakman Consulting Ltd | Financial services | 2014 |
| Speakman Properties (Braxted) Ltd | Real estate | 2021 |
| Spencer Asbestos Solutions Ltd | Professional & scientific | 2023 |
| Sphere Logistics Limited | Transport & logistics | 2020 |
| Spill Studios Ltd | Administrative & support | 2011 |
| Spires Electrical and Solar Ltd | Construction | 2026 |
| Sporting Torque Ltd | Wholesale & retail | 2013 |
| Sports & Playground Services UK Limited | Manufacturing | 2003 |
| Sports Videography Limited | Information & communication | 2018 |
| Spot on Laminators Limited | Manufacturing | 2000 |
| Spring Lodge Centre Limited | Wholesale & retail | 2000 |
| SPW Consulting Limited | Information & communication | 2026 |
| Squares & Circles Pizza Company Ltd | Hospitality | 2022 |
| Squeezd Limited | Extraterritorial | 2024 |
| Squirrel Group Holdings Ltd | Financial services | 2025 |
| SRD Associates (INT) Limited | Professional & scientific | 2019 |
| Sree Gnana Properties Limited | Real estate | 2025 |
| SRY Solutions Ltd | Financial services | 2017 |
| SSG Design and Development Ltd | Manufacturing | 2023 |
| SSL Scaffolding Contracts Ltd | Construction | 2018 |
| ST Catherines Hove Limited | Real estate | 2023 |
| ST. Georges Court Management (Witham) Limited | Households | 1986 |
| ST. Threadz Limited | Wholesale & retail | 2025 |
| Staffordshire Internet Services Limited | Professional & scientific | 1995 |
| Stalee Limited | Manufacturing | 2018 |
| Standup Ltd | Education | 2025 |
| Staples Holdings Ltd | Wholesale & retail | 2019 |
| Stapleton Property Limited | Financial services | 2019 |
| Stars&Flamesbye Limited | Wholesale & retail | 2026 |
| Steadman Commercial Services Limited | Professional & scientific | 2014 |
| Stefre House Property Limited | Households | 2019 |
| Stereopsys Ltd | Health & social care | 2010 |
| Stevan Webb & SON Roofing Ltd | Construction | 2023 |
| Steve Webb Advisory Limited | Information & communication | 2018 |
| Steven Green Financial Planning Limited | Financial services | 2015 |
| Stevie Sparks Electrical Ltd | Construction | 2023 |
| Stirbet Ltd | Construction | 2020 |
| Stirling Internet Services Limited | Professional & scientific | 1995 |
| Stone Cold Cooling and Refrigeration Limited | Energy | 2024 |
| Storagenstuff Limited | Administrative & support | 2009 |
| Stowmarket Plumbing and Bathroom Centre Limited | Wholesale & retail | 2007 |
| Strategic Outsourcing Services Limited | Administrative & support | 2018 |
| Streetsmart Traffic Management Limited | Administrative & support | 2026 |
| Strength and Rehab Coaching Ltd | Arts & recreation | 2026 |
| Strive Sponsorship Limited | Professional & scientific | 2011 |
| Subeyda Aesthetics Limited | Other services | 2026 |
| Submit Sports Ltd | Wholesale & retail | 2017 |
| Sucure Biotech Limited | Professional & scientific | 2024 |
| Suffolk Contracts Limited | Construction | 2019 |
| Suffolk Internet Services Limited | Professional & scientific | 1995 |
| Suffolk Property Developers Ltd | Construction | 2017 |
| Summit Essex Ltd | Construction | 2018 |
| Super Slim Glazing Ltd | Manufacturing | 2022 |