| South Essex Property Development Ltd | Real estate | 2026 |
| South House Farm Investments Limited | Construction | 2002 |
| Southeast Piling Ltd | Construction | 2018 |
| Southern Way (Folkestone) Limited | Construction | 2021 |
| Southminster Developments (Management) Ltd | Real estate | 2021 |
| Sparkwright Limited | Construction | 2012 |
| Sparky Mark Electrical Limited | Manufacturing | 2000 |
| Spencer Sims Limited | Financial services | 2018 |
| Spicer's Carpentry Ltd | Construction | 1998 |
| Splash International Limited | Professional & scientific | 1994 |
| Splendid Car Valeting Service Ltd | Wholesale & retail | 2021 |
| Splendid Valeting Car Wash Ltd | Administrative & support | 2017 |
| Spraggon Engineering Ltd | Professional & scientific | 2026 |
| Spring Elms Ltd | Real estate | 2026 |
| Spring Hill Flat Management Limited | Real estate | 1979 |
| Spring Residential Investments Limited | Real estate | 2022 |
| Springett Properties Limited | Real estate | 2025 |
| Springfield Barges Limited | Administrative & support | 2002 |
| SPS Brickwork Holdings Limited | Construction | 2021 |
| SPS Brickwork Limited | Construction | 2012 |
| Spurpark Limited | Professional & scientific | 1985 |
| SPY College Limited | Information & communication | 2009 |
| SQ Noble Trading Co., Ltd | Administrative & support | 2023 |
| SRT Transport Ltd | Transport & logistics | 2014 |
| SSE Properties LLP | | 2009 |
| ST Andrew East Parade Ltd | Real estate | 2025 |
| ST Andrew Global Ltd | Construction | 2024 |
| ST Andrew Heathfield Ltd | Real estate | 2026 |
| ST Andrew Independent Holding Group Limited | Real estate | 2025 |
| ST Clements Walk Block M Management Company Limited | Real estate | 1990 |
| ST Edmunds Flats Management Limited | Households | 1966 |
| ST Jude's Laundry Ltd | Other services | 2024 |
| Stable Property Investments Limited | Real estate | 2025 |
| Stag Solar Solutions Ltd | Construction | 2020 |
| Stag Studios Limited | Information & communication | 2003 |
| Stage Door Transport Ltd | Transport & logistics | 2023 |
| Standard Apartments (N8 8AW) Limited | Extraterritorial | 2018 |
| Stanford Design Limited | Wholesale & retail | 2009 |
| Stanton Executive Services Limited | Professional & scientific | 2009 |
| Starlight Care Staffing Ltd | Administrative & support | 2020 |
| Status Education C.I.C. | Education | 2020 |
| Steam TUG Brent Ltd | Arts & recreation | 2010 |
| Steel Box Self Storage Ltd | Transport & logistics | 2023 |
| Steeple General Services Ltd | Construction | 2005 |
| Stefario Investment Group Limited | Professional & scientific | 2024 |
| Stenings Scrivener Ltd | Professional & scientific | 2011 |
| Step on Safety Properties Limited | Financial services | 2015 |
| Stephen-Paul Prizeman Ltd | Extraterritorial | 2025 |
| Sterling Homecare Limited | Health & social care | 2025 |
| Sterling Ridge Motor Company Ltd | Wholesale & retail | 2025 |
| Sterling Supergroup Limited | Hospitality | 1989 |
| Steve Hyams Tools Ltd | Wholesale & retail | 2010 |
| Stevelspv Limited | Real estate | 2020 |
| Steven Stubbs Limited | Wholesale & retail | 2021 |
| Stinky Mick Productions Ltd | Professional & scientific | 2011 |
| Stour Bay Trading Co. Limited | Wholesale & retail | 1999 |
| Stow I.T. Solutions Limited | Information & communication | 2007 |
| Stowehouse Limited | Administrative & support | 2022 |
| Strategeyes Limited | Professional & scientific | 2013 |
| Stringers World Limited | Wholesale & retail | 2006 |
| Stuart Allan Holdings Limited | Other services | 2019 |
| Stuart Allan Maintenance Limited | Construction | 2020 |
| Stud Farm Contracting Ltd | Agriculture & fishing | 2020 |
| Studio Forty Seven Ltd | Professional & scientific | 2024 |
| Studio Mattr Limited | Professional & scientific | 2016 |
| Studio Self Limited | Other services | 2020 |
| STUDIO23 Consultancy Ltd | Professional & scientific | 2025 |
| Style Carpentry Ltd | Construction | 2008 |
| Stylish Cafe Ltd | Hospitality | 2017 |
| Suffolk Securities Ltd | Financial services | 2025 |
| Sujo Ltd. | Professional & scientific | 2013 |
| Summer Advisory Limited | Administrative & support | 2026 |
| Sundaze Landscapes Ltd | Administrative & support | 2020 |
| Sunnyside Dental & Health Limited | Health & social care | 2025 |
| Super Kitchen Creative Limited | Information & communication | 2018 |
| Supercars of Essex Limited | Wholesale & retail | 2014 |
| Supreme School of Motoring Limited | Education | 2024 |
| Sustainable Staffing Solutions Limited | Administrative & support | 2025 |
| SV Electrics Limited | Construction | 2016 |
| SVJ Advisory Limited | Administrative & support | 2018 |
| SVT Properties Limited | Real estate | 1978 |
| Swaby Creative Limited | Arts & recreation | 2018 |
| Swansley Green (Cambourne) Management Company Limited | Households | 2003 |
| SWD Properties Limited | Financial services | 1988 |
| Swift Brickwork Contractors Limited | Construction | 1992 |
| Swift Construction Group Limited | Financial services | 2019 |
| Swift Developments Limited | Construction | 2000 |
| Swift UK Holdings Limited | Financial services | 2022 |
| Swiftbot Maritime Innovations Ltd | Manufacturing | 2025 |
| Swingsense Ltd | Education | 2026 |
| Swiss House Essex Limited | Construction | 2012 |
| Swiss House Rentals Ltd | Real estate | 2023 |
| Swisstematics Limited | Financial services | 2016 |
| Switch Donn Ltd | Construction | 2024 |
| Sylvia Reyes Limited | Education | 2015 |
| Sync Recruitment Limited | Administrative & support | 2014 |
| Synergia Technology Solution Ltd | Administrative & support | 2022 |
| SYS3 Limited | Information & communication | 2001 |
| Sz&W Limited | Wholesale & retail | 2013 |
| T.R. Brown Plumbing and Heating Limited | Construction | 2007 |