| Seagain Limited | Hospitality | 2018 |
| Seamen's Rooms Tenby Limited | Households | 2003 |
| Seanote Ltd | Hospitality | 2013 |
| Seaquins (Westcliff) | Health & social care | 2020 |
| Seaside Rocks (Southend) Limited | Hospitality | 2013 |
| Seaside Rocks Ice Cream Limited | Manufacturing | 2014 |
| Seaview Property Services Ltd | Administrative & support | 2026 |
| Sebert Ltd | Professional & scientific | 2023 |
| SEED27 Limited | Information & communication | 2026 |
| Selsey Good Limited | Hospitality | 2026 |
| Send IT Solutions Ltd | Information & communication | 2025 |
| Sensecode Limited | Wholesale & retail | 2019 |
| Sentia Ltd | Financial services | 2024 |
| Serenedwell Limited | Health & social care | 2024 |
| Serenity Springs Residences Ltd | Health & social care | 2024 |
| Sevenhills Infotech Limited | Information & communication | 2020 |
| Seymour House (Westcliff) Freehold Limited | Households | 2020 |
| Seymour House RTM Company Ltd | Households | 2019 |
| SGO Lifestyle Ltd | Health & social care | 2025 |
| Shadivy Express Ltd | Wholesale & retail | 2021 |
| Shaloha Limited | Hospitality | 2020 |
| Sharpe Tankers Limited | Transport & logistics | 2025 |
| Shaun Bristow Ltd | Construction | 2019 |
| Shawday Healthcare Ltd | Administrative & support | 2026 |
| Shelby GT350 Ltd | Health & social care | 2023 |
| Shelby GT350R Ltd | Health & social care | 2025 |
| Shelby GT500 Ltd | Health & social care | 2024 |
| Shella Property Limited | Real estate | 2025 |
| Shelltop Limited | Hospitality | 2018 |
| Sheppard Wright Ltd | Construction | 2018 |
| Shery Solutions Limited | Information & communication | 2024 |
| Shield Consort Limited | Information & communication | 2014 |
| Shield Konsult Limited | Real estate | 2015 |
| Shifts and Perspectives Ltd | Professional & scientific | 2021 |
| Shisha-On-Sea Ltd | Manufacturing | 2020 |
| Shishi Estates Ltd | Real estate | 2026 |
| Shlomo Shop Ltd | Real estate | 2017 |
| Shoebury Dragon Limited | Hospitality | 2026 |
| Shrw Estates Limited | Real estate | 2025 |
| Shun Cheung Limited | Hospitality | 2019 |
| SIA &a Limited | Administrative & support | 2016 |
| Silk Spoon Limited | Hospitality | 2025 |
| Silver Sparks Entertainments Ltd | Arts & recreation | 2017 |
| Simplicity Cremations Ltd | Other services | 2019 |
| Simply Devine Cleaning Limited | Administrative & support | 2025 |
| Simply Food Safety Ltd | Hospitality | 2021 |
| Simranjeet Ltd | Construction | 2024 |
| Sinachi Afro Global Limited | Wholesale & retail | 2024 |
| Singleton Construction Company Ltd | Construction | 2020 |
| Sinova Ltd | Real estate | 2019 |
| Sizzling WOK 168 Limited | Hospitality | 2019 |
| SK Ultrasound Limited | Health & social care | 2021 |
| SKG Maintenance Ltd | Construction | 2020 |
| SKV Anaesthetic Services Ltd | Health & social care | 2025 |
| Sleeper Service Ltd | Information & communication | 2015 |
| Slfink Ltd | Real estate | 2023 |
| Slfink SUB Ltd | Real estate | 2023 |
| Small Order Metal Company Ltd | Wholesale & retail | 2018 |
| Smart Britannia Limited | Information & communication | 2015 |
| Smart Helmet Technology Ltd | Manufacturing | 2025 |
| Smart Hotels and Restaurants Limited | Hospitality | 2023 |
| Smart Mens Shoes Ltd | Wholesale & retail | 2018 |
| Smart Money Management Services Limited | Other services | 2009 |
| Smartfibreinstall Ltd | Manufacturing | 2023 |
| Smartphones Tech Limited | Information & communication | 2025 |
| Smash Chicken Limited | Hospitality | 2023 |
| SMK Property Management Limited | Households | 2025 |
| Smoove Construction Limited | Construction | 2015 |
| SMZ Raza & Co Ltd | Wholesale & retail | 2025 |
| Snappy Offsite Storage Limited | Information & communication | 2006 |
| SNT Training Services Limited | Education | 2022 |
| Soar Technology Ltd | Extraterritorial | 2018 |
| Soartech Properties Ltd | Real estate | 2023 |
| Software Retailers and Developers Ltd | Administrative & support | 2016 |
| Sonar Recruitment Limited | Administrative & support | 2015 |
| Sopa Thai Cuisine Ltd | Hospitality | 2024 |
| Sopa Thai Westcliff Ltd | Hospitality | 2024 |
| South East Fire Ltd | Construction | 2025 |
| Southbourne Physiotherapy Limited | Health & social care | 2009 |
| Southbourne Shipping Limited | Transport & logistics | 2010 |
| Southbourne Surgery Limited | Health & social care | 2002 |
| Southend Accountancy Services Limited | Professional & scientific | 2025 |
| Southend Barber Shop Ltd | Other services | 2025 |
| Southend Best Pizza Limited | Hospitality | 2025 |
| Southend City Roofing Ltd | Construction | 2023 |
| Southend Fish and Chips Limited | Hospitality | 2021 |
| Southend Fish Ltd | Wholesale & retail | 2025 |
| Southend Home & Auto Clean Ltd | Administrative & support | 2026 |
| Southend Pizza Ltd | Hospitality | 2021 |
| Southern Hongkie Ltd | Hospitality | 2025 |
| Southshore Holdings Ltd | Extraterritorial | 2019 |
| Southview Ventures Ltd | Real estate | 2024 |
| Sparkle & Shine Time Limited | Administrative & support | 2026 |
| Spdns Nurse Care Community Interest Company | Health & social care | 1988 |
| Special Events (London) Ltd | Administrative & support | 2010 |
| Speck Detectors Cleaning Ltd | Administrative & support | 2025 |
| Spinecare Solution Limited | Health & social care | 2025 |
| Spirulina Ltd | Hospitality | 2018 |
| SPJ Healthcare Limited | Health & social care | 2003 |
| Spong Property Services Limited | Real estate | 2004 |