| Santosh Goyal Foundation CIC | Health & social care | 2025 |
| Sanuraa Limited | Information & communication | 2011 |
| Sanyu MED Limited | Health & social care | 2025 |
| SAO Ltd | Information & communication | 2015 |
| Sapphire Bricks & Mortar Ltd | Real estate | 2018 |
| Sapphire Estates Ltd | Real estate | 2024 |
| Sapphire Specialist Cleaning Ltd | Administrative & support | 2021 |
| Sareen Assets Ltd | Real estate | 2015 |
| Sarisoftware Solutions Limited | Information & communication | 2012 |
| Sarunas Scaffolding Limited | Construction | 2021 |
| Sash Carpentry Limited | Construction | 2016 |
| Satellite Health Care Limited | Health & social care | 2014 |
| Satya Group Ltd | Real estate | 2020 |
| Sava Beauty Ltd | Wholesale & retail | 2025 |
| Sawer Limited | Health & social care | 2022 |
| Saxby Consulting Limited | Information & communication | 2023 |
| Saxon Electrical Contractors Ltd | Construction | 2019 |
| Saxophones Holdings Limited | Wholesale & retail | 2023 |
| Saxophones Limited | Wholesale & retail | 2002 |
| Sayda Trade Limited | Wholesale & retail | 2025 |
| SB Fine Ltd | Construction | 2026 |
| SB Live Ltd | Information & communication | 2021 |
| SB Shopper Ltd | Wholesale & retail | 2022 |
| SB34 Ltd | Professional & scientific | 2023 |
| SBA Consulting Global Ltd | Professional & scientific | 2019 |
| SBD Holdings Essex Limited | Financial services | 2025 |
| SBJ Management Ltd | Professional & scientific | 2023 |
| SBPROPERTYMAINTENANCE4 Ltd | Construction | 2026 |
| SCA Electrical Contracting Ltd | Construction | 2018 |
| SCA Group Limited | Manufacturing | 1999 |
| Scaffold Safe Ltd | Construction | 2024 |
| Scaffoldforce Ltd | Construction | 2025 |
| Scales Plastering Limited | Construction | 2003 |
| Scalia Design Limited | Manufacturing | 2016 |
| Scammell Electrical Solutions Ltd | Construction | 2016 |
| Scan Shipping Limited | Extraterritorial | 1990 |
| Scane, Spratt and Lilley Electrical Limited | Construction | 2021 |
| Scanners and Spanners Company Limited | Wholesale & retail | 2008 |
| Scarlet Titan Limited | Information & communication | 2016 |
| Scarlett Financial Limited | Financial services | 2016 |
| Scars Tattoo Studio Ltd | Wholesale & retail | 2024 |
| Scbc Consultancy Limited | Professional & scientific | 2015 |
| Scents and Love by Tania Allwood Limited | Wholesale & retail | 2020 |
| Schija Construction Ltd | Construction | 2026 |
| Schore Group Limited | Construction | 2015 |
| Schore Limited | Construction | 2014 |
| Scintillant Limited | Wholesale & retail | 2023 |
| Scope Physiotherapy Clinic Limited | Health & social care | 2016 |
| Scotch Bonnet Funding Limited | Financial services | 2022 |
| Scott Borley Promotions Ltd | Arts & recreation | 2024 |
| Scott Brown Engineering Limited | Professional & scientific | 2007 |
| Scott Goodliffe Scaffolding Limited | Construction | 2015 |
| Scott Klein & Fisher Limited | Professional & scientific | 1996 |
| Scott LEE Jones Limited | Construction | 2025 |
| Scott Little Productions Ltd | Manufacturing | 2021 |
| Scott Myles Interior UK Limited | Construction | 2014 |
| Scottie's Food Truck Ltd | Hospitality | 2024 |
| Scotts Cladding Ltd | Construction | 2026 |
| Scurfield and Associates Ltd | Financial services | 2019 |
| SD Haulage Ltd | Transport & logistics | 2022 |
| SD Healthcare Services Ltd | Health & social care | 2016 |
| SDL Homes Essex Limited | Construction | 2022 |
| SDS Fixing Ltd | Construction | 2022 |
| SE Haulage Limited | Transport & logistics | 2025 |
| Sea Harrier Preservation Project CIC | Manufacturing | 2025 |
| Seaborne Group Limited | Other services | 2025 |
| Seadg Ltd | Health & social care | 2025 |
| Seadrift Property Group Limited | Real estate | 2026 |
| Seames Ltd | Real estate | 2024 |
| Seana Limited | Construction | 2015 |
| Search 4 Mortgages Limited | Extraterritorial | 2004 |
| Seasons Bar Limited | Hospitality | 2013 |
| Seated Acupressure Therapy Limited | Health & social care | 1999 |
| Seaview Healthcare Group Ltd | Health & social care | 2022 |
| Seby 23 Limited | Transport & logistics | 2018 |
| Seby Construct Ltd | Construction | 2018 |
| Secabro Group Ltd | Financial services | 2025 |
| Secaplus Limited | Administrative & support | 2017 |
| Sector Staff Ltd | Administrative & support | 2013 |
| Secure Future Holdings Limited | Real estate | 2019 |
| Secure Technology Analytics Ltd | Professional & scientific | 2018 |
| Securebuild Consulting Ltd | Professional & scientific | 2025 |
| Security Basics Toolkit Ltd | Information & communication | 2025 |
| Security Installations Limited | Administrative & support | 2021 |
| Securityguys Ltd | Information & communication | 2025 |
| Seddon Atkinson Vehicles Limited | Extraterritorial | 1951 |
| Sedges Pet Styling Limited | Other services | 2021 |
| Seed Recruitment Limited | Administrative & support | 2017 |
| Seekers Property Investments Limited | Real estate | 2004 |
| Seffa (South Essex Feather & FUR Auctions) | Other services | 2014 |
| Selaelo Limited | Health & social care | 2011 |
| Selah Wellbeing Ltd | Health & social care | 2022 |
| Select Fitters Limited | Manufacturing | 2023 |
| Selective Security Limited | Administrative & support | 2025 |
| Selex Elsag Limited | Information & communication | 1969 |
| Selex ES International Ltd | Financial services | 1969 |
| Self Accounts Ltd | Professional & scientific | 2017 |
| Selk Scaffolding & Design Limited | Construction | 2018 |
| Seloulle Ltd | Wholesale & retail | 2025 |
| Seminara Construction Ltd | Construction | 2022 |