| Saturate Marketing Ltd | Professional & scientific | 2023 |
| Saunders Detailing Limited | Administrative & support | 2022 |
| Save Beane Marshes Limited | Arts & recreation | 2019 |
| Save Bengeo Field Ltd | Information & communication | 2025 |
| Savvy Savers Limited | Professional & scientific | 2024 |
| Savvybrand Ltd | Professional & scientific | 2024 |
| SB Enterprise Holdings Limited | Financial services | 2022 |
| SBG Roofing Limited | Construction | 2025 |
| SC Decor London Limited | Construction | 2023 |
| SC Insurance Brokers Limited | Financial services | 2006 |
| Scaleup Engineering Ltd | Information & communication | 2021 |
| Scanley Ltd | Information & communication | 2024 |
| Scarf UP London Limited | Wholesale & retail | 2025 |
| SCB Homes Limited | Real estate | 2022 |
| SCENE2 Limited | Administrative & support | 1999 |
| Scenic Assist Ltd | Transport & logistics | 2014 |
| Scooting Computing Ltd | Information & communication | 2018 |
| SCOPE360 Solutions Limited | Information & communication | 2010 |
| Scopos Consulting Limited | Professional & scientific | 2012 |
| Scorpio Enterprises Limited | Real estate | 1993 |
| Scotch Accounting Ltd | Professional & scientific | 2021 |
| Scott Heron Limited | Other services | 2019 |
| Scott Trendall Limited | Administrative & support | 2014 |
| Scout Land & Commercial Limited | Real estate | 2021 |
| Scrase Financial Ltd | Financial services | 2004 |
| Scrubs Cleaning Solutions Ltd | Administrative & support | 2014 |
| Scyla Ltd | Wholesale & retail | 2023 |
| SD Robinson Ltd | Agriculture & fishing | 2015 |
| Sdja Limited | Wholesale & retail | 2025 |
| SDT Group Ltd | Construction | 2025 |
| Seafield Psychology Limited | Health & social care | 2022 |
| Sean Walkinshaw Racing Limited | Professional & scientific | 2007 |
| Seaplastec Ltd | Manufacturing | 2019 |
| Seasons Home Interiors Limited | Other services | 2025 |
| Sebmax Services Limited | Financial services | 2017 |
| Second Avery Down Management Co. Limited | Households | 1996 |
| Secure-Ops Events Security & Logistics Ltd | Administrative & support | 2015 |
| Seffco International Limited | Wholesale & retail | 2011 |
| SEG Group Ltd | Wholesale & retail | 2022 |
| Sele Mill RTM Company Limited | Households | 2010 |
| Seltek Consultants Limited | Administrative & support | 2002 |
| Selwyn Industrial Services Limited | Administrative & support | 2010 |
| Send Wellbeing Limited | Education | 2026 |
| Seneca Business Services Limited | Administrative & support | 2026 |
| Sensational Sports Ltd | Education | 2025 |
| Sentag Limited | Administrative & support | 2013 |
| Sentek Solutions Limited | Wholesale & retail | 2004 |
| September Flowers Ltd | Wholesale & retail | 2015 |
| Sequin Art Limited | Manufacturing | 2016 |
| Servucare Ltd | Administrative & support | 2020 |
| SET 2 Build Group Ltd | Construction | 2024 |
| Sewardstone Self Storage Ltd | Real estate | 2023 |
| Sexysavvy Limited | Professional & scientific | 2024 |
| Seymour Place (Hornchurch) Management Limited | Households | 2001 |
| SFL Power Solutions Limited | Professional & scientific | 2016 |
| SFW Trade Limited | Wholesale & retail | 2023 |
| SG Van Protection Ltd | Construction | 2026 |
| SGW Carpentry Limited | Construction | 2014 |
| Shaded the Studio Ltd | Information & communication | 2024 |
| Shadowleaf Landscapes Limited | Administrative & support | 2020 |
| Shain Ltd | Hospitality | 2018 |
| Shakespeare Court Residents Association Limited | Real estate | 1976 |
| Shamiraj (Chemists) Limited | Wholesale & retail | 1993 |
| Shanley Associates Limited | Professional & scientific | 2006 |
| Sharon Lawton Coaching Limited | Education | 2012 |
| Sharp Heating and Plumbing Ltd | Energy | 2019 |
| Sharp Renewables Limited | Administrative & support | 2024 |
| Sharp Stone Granite Limited | Construction | 2018 |
| Sharps Windows & Doors Ltd | Construction | 2018 |
| Shawlec Limited | Administrative & support | 2020 |
| Sheena Storah and Associates Ltd. | Health & social care | 2002 |
| Shefbrook Ltd | Wholesale & retail | 2018 |
| Shepherds of Hertford Limited | Real estate | 2006 |
| Shine Bright Consulting Limited | Information & communication | 2018 |
| Shine SL Limited | Health & social care | 2022 |
| Shinfield Park Building Management Company Limited | Households | 2006 |
| SHINW3 Ltd | Health & social care | 2024 |
| Shire Surveying Limited | Construction | 1985 |
| Shivam Holdings Ltd | Financial services | 2016 |
| Shivam Pharmacy Limited | Wholesale & retail | 2008 |
| Shjsnbkdjh Ltd | Extraterritorial | 2021 |
| Shoalcap Limited | Administrative & support | 2026 |
| Shoalcap Rural Residential Limited | Construction | 2026 |
| Shore Limited | Professional & scientific | 2002 |
| Show OFF Hertford Ltd | Other services | 2025 |
| Sieley Property Management Limited | Real estate | 2019 |
| Sierra November Limited | Administrative & support | 2012 |
| Signature Cleaning Ltd | Administrative & support | 2025 |
| Signature Creative Solutions Limited | Information & communication | 2010 |
| Siistm Resources Ltd | Wholesale & retail | 2019 |
| Silicon Management Limited | Professional & scientific | 1994 |
| Silken Limited | Other services | 1990 |
| Silkendo Limited | Professional & scientific | 2022 |
| Silver Howe Commodities Ltd | Professional & scientific | 2017 |
| Simon Lloyd Clinics Ltd | Health & social care | 2011 |
| Simonsberg Ltd | Professional & scientific | 2014 |
| Simplify Orthotics Ltd | Wholesale & retail | 2023 |
| Simply Swim Limited | Other services | 2020 |
| Simply Wood Joinery Ltd | Manufacturing | 2021 |
| Simpson and West Construction Ltd | Construction | 2026 |