| South East Essex Maintenance Limited | Construction | 2021 |
| South East Essex Prosthetics Ltd | Manufacturing | 2022 |
| South East MEP Ltd | Construction | 2025 |
| South Essex Airport Transfers Limited | Transport & logistics | 2024 |
| South West Wallcoating Limited | Construction | 2001 |
| Southend Airport B&B Ltd | Hospitality | 2020 |
| Southend City Transport Ltd | Transport & logistics | 2023 |
| Southend Healthcare Limited | Health & social care | 2009 |
| Southend in Sight | Other services | 1998 |
| Southend Smart Repairs Ltd | Wholesale & retail | 2022 |
| Southend Vision Trading Ltd | Wholesale & retail | 2007 |
| Southern Geotechnical Design Limited | Professional & scientific | 2004 |
| Southern Spa Services Ltd | Construction | 2020 |
| Southside Freehold Limited | Real estate | 2010 |
| Sovereign Views Management Company Limited | Households | 2003 |
| Space Architecture Limited | Professional & scientific | 2002 |
| Spark! Consulting Ltd | Professional & scientific | 2017 |
| Specialist PRL Ltd | Other services | 2018 |
| Specialist Welding Services Essex Limited | Manufacturing | 2019 |
| Spectrum Plumbing GAS & Heating Ltd | Construction | 2023 |
| Spiceboat Limited | Other services | 2013 |
| Spine Surgery Consultants Ltd | Extraterritorial | 2016 |
| Spirit Software Limited | Information & communication | 2013 |
| Spriggs Motors Ltd | Wholesale & retail | 2024 |
| Sprintpoint Ltd | Information & communication | 2014 |
| Squaretop Properties Limited | Real estate | 2023 |
| SRH Recruiting Ltd | Administrative & support | 2026 |
| SS1 Productions Limited | Arts & recreation | 2018 |
| Sss&A Services Ltd | Professional & scientific | 2025 |
| Sssprs Consulting Limited | Information & communication | 2026 |
| ST Johns Court (Westcliff) RTM Company Limited | Households | 2022 |
| ST. Clements Court East Limited | Households | 1981 |
| ST. John's and Ravenscourt (Westcliff-On-Sea) Limited | Households | 1977 |
| Stanmar Consulting Limited | Professional & scientific | 2013 |
| Star Health Solutions Limited | Wholesale & retail | 2019 |
| Star Leisure Recovery Limited | Transport & logistics | 2003 |
| Starfare Limited | Other services | 2009 |
| Starkey Property Management Ltd | Real estate | 2021 |
| Starley Electrical Limited | Construction | 2022 |
| Station Road Maintenance Limited | Households | 1989 |
| Stax Fire Sprinklers Ltd | Construction | 2025 |
| Stay Box Fresh Ltd | Other services | 2019 |
| Stealth Industries Ltd | Transport & logistics | 2020 |
| Steelspan Limited | Construction | 2018 |
| Steelspan Security Limited | Construction | 2015 |
| Stellar SIX Limited | Wholesale & retail | 2020 |
| Stephen Vine Ltd | Construction | 2025 |
| Stevmond Ltd | Professional & scientific | 2024 |
| Stirling Training Consultancy Ltd | Education | 2020 |
| Stoa Consulting Limited | Information & communication | 2020 |
| Stonehill Properties Limited | Professional & scientific | 1989 |
| Stoneman Collins Limited | Wholesale & retail | 2024 |
| Store Bright Containers Ltd | Wholesale & retail | 2016 |
| Stratelle Limited | Professional & scientific | 2025 |
| Stretch FX (Mayfair) Ltd | Professional & scientific | 2024 |
| Stringer Carpentry Ltd | Construction | 2022 |
| Strings Direct Holdings Limited | Administrative & support | 2017 |
| Strings Direct Limited | Wholesale & retail | 2006 |
| Structureone Projects Limited | Professional & scientific | 2025 |
| Studio 200 Group Limited | Financial services | 2017 |
| Studio GDV Limited | Professional & scientific | 2025 |
| Sudeley Gardens (Hockley) Management Company Limited | Real estate | 1983 |
| Sudoro Ltd | Information & communication | 2016 |
| Suffolk Collections Ltd | Administrative & support | 2024 |
| Suki Media Ltd | Administrative & support | 2023 |
| Sunnyside Sales Ltd | Wholesale & retail | 2023 |
| Sunray Auto Repairs Limited | Wholesale & retail | 2017 |
| Sunrise Sips Limited | Hospitality | 2025 |
| Sunshine Glow Limited | Other services | 2024 |
| Support Sport Media Limited | Arts & recreation | 2025 |
| Supreme Installations (South East) Limited | Manufacturing | 1999 |
| Supreme Turf & Soils Limited | Other services | 2008 |
| Sure Fitness Limited | Administrative & support | 2008 |
| Sureincome Limited | Construction | 1991 |
| Svmt Limited | Wholesale & retail | 2025 |
| Swallow Barn Property Limited | Real estate | 2025 |
| Swan Autos Limited | Wholesale & retail | 2025 |
| Swansoft Consultancy Limited | Information & communication | 1996 |
| Sweatsearch Ltd | Administrative & support | 2020 |
| Sweet Purple Ltd | Administrative & support | 2025 |
| Sweetbyte Ltd | Information & communication | 2016 |
| Swisstech Recruitment Limited | Administrative & support | 2020 |
| SWS Security Systems Limited | Administrative & support | 2004 |
| SX Gardens Limited | Other services | 2023 |
| Syncro Stream Limited | Professional & scientific | 2012 |
| T & B Security Services Ltd | Administrative & support | 2019 |
| T a G Green Limited | Administrative & support | 2012 |
| T-Bird Limited | Hospitality | 2004 |
| T. Gadd Engineering Services Limited | Professional & scientific | 2025 |
| T.L.C. Glazing Limited | Manufacturing | 1996 |
| Tabor Farms Limited | Agriculture & fishing | 1979 |
| Tadintune Limited | Information & communication | 2018 |
| Take the Lead - Dog Walking Ltd | Other services | 2026 |
| Tankerville Drive Residents Association Limited | Households | 2000 |
| Tarbox Building Services Limited | Construction | 2012 |
| Taylor Made Cues Limited | Manufacturing | 2022 |
| TB Accounts Ltd | Professional & scientific | 2005 |
| TBA Property Ltd | Real estate | 2024 |
| TBA Property Management Ltd | Households | 2024 |
| TBA Sourcing Ltd | Real estate | 2024 |