| Secure Black Cabs Ltd | Transport & logistics | 2020 |
| Secure Box Services Limited | Arts & recreation | 2006 |
| SEE Through Data Limited | Information & communication | 2009 |
| Seed Enterprise Consulting Limited | Administrative & support | 2025 |
| Seeker Technologies Limited | Information & communication | 2026 |
| Segrave & Partners LLP | | 2008 |
| Seicho International Ltd | Administrative & support | 2024 |
| Seira Tech Limited | Information & communication | 2024 |
| Select Flat Roofing Limited | Construction | 2024 |
| Select IOT Limited | Wholesale & retail | 2022 |
| Selkent Steels Limited | Extraterritorial | 2013 |
| Sellution Holdings Ltd | Information & communication | 2026 |
| SEN Trust Southend | Education | 2012 |
| Senda Luxe Limited | Professional & scientific | 2025 |
| Senkoun Integrated Healthcare Solutions Ltd | Manufacturing | 2023 |
| Sensus Construction Ltd | Construction | 2010 |
| Septfive Limited | Information & communication | 2022 |
| Sequre IT Limited | Wholesale & retail | 2024 |
| Servform Ltd | Information & communication | 2025 |
| SET Building and Brickwork Ltd | Construction | 2025 |
| Settora Limited | Real estate | 2025 |
| Seven Hills Pharma Consulting Ltd | Professional & scientific | 2023 |
| Seven South East Limited | Financial services | 2017 |
| Seven Space Holistic Learning CIC | Education | 2025 |
| Sewell Estates Ltd | Real estate | 2024 |
| Sewell Produce Ltd | Wholesale & retail | 2025 |
| Sezhat Limited | Wholesale & retail | 2026 |
| SFG Club Ltd | Arts & recreation | 2015 |
| SG Brands Ltd | Wholesale & retail | 2020 |
| SG Coaching Limited | Arts & recreation | 2018 |
| SG Properties HMO Limited | Hospitality | 2021 |
| Sgcnr.Net Ltd | Information & communication | 2026 |
| Sgdr Coaching Limited | Arts & recreation | 2021 |
| SGS Carpentry Limited | Manufacturing | 2019 |
| SGS Construction (Essex) Ltd | Construction | 2024 |
| SH Accountancy Services Ltd | Professional & scientific | 2007 |
| SH Logistics Ltd | Transport & logistics | 2025 |
| Shaban (UK) Limited | Wholesale & retail | 2014 |
| Shabi & Shanchi Limited | Construction | 2026 |
| Shadrack - Wallace Limited | Manufacturing | 2000 |
| Shaftesbury Plant Hire Limited | Construction | 2009 |
| Shala Transport Ltd | Transport & logistics | 2026 |
| Shambhala Studios Limited | Other services | 2006 |
| Shane N Design Ltd | Professional & scientific | 2023 |
| Shannon Storage Limited | Extraterritorial | 2022 |
| Sharp Bricks Limited | Real estate | 2024 |
| Sharp Edge (UK) Ltd | Professional & scientific | 2011 |
| Sharp Resources Limited | Administrative & support | 2012 |
| Sharpe Estates Ltd | Real estate | 2021 |
| Sharpe Mortgages Ltd | Financial services | 2018 |
| Shasvat Limited | Wholesale & retail | 2024 |
| Shaw.Med Ltd | Health & social care | 2022 |
| Shawline Associates Limited | Professional & scientific | 2021 |
| Sheevnali Limited | Wholesale & retail | 1990 |
| Shelby Flooring Contractors Ltd | Manufacturing | 2020 |
| Shenfield Auto Services Limited | Wholesale & retail | 2012 |
| Shenfield Road Development Limited | Construction | 2025 |
| Shepdart Limited | Information & communication | 1985 |
| Shepherd Building Group Limited | Professional & scientific | 1960 |
| Sherringham Interiors Limited | Other services | 2007 |
| Shillamill Farm Limited | Hospitality | 2021 |
| Shivhari Limited | Health & social care | 2025 |
| Shoe Embassy London Ltd | Wholesale & retail | 2016 |
| Shoes Red Ltd | Real estate | 2026 |
| Shore Lettings & Property Management Limited | Real estate | 2024 |
| Shore Roofing Limited | Construction | 2019 |
| Shoreditch Planning and Design Services LLP | | 2002 |
| Shoreline Communications Limited | Other services | 2024 |
| Short Safety Solutions Limited | Construction | 2022 |
| Short-Leg Travel Limited | Extraterritorial | 2010 |
| Show Dogz Limited | Arts & recreation | 2022 |
| Shreyam Medical Services Limited | Education | 2022 |
| Shri Preston Road Limited | Real estate | 2025 |
| Shri Preston Road SPV Limited | Real estate | 2025 |
| Shri Property Investments Limited | Real estate | 2024 |
| Shrimperzone.Com Limited | Information & communication | 2006 |
| SHS Professional Limited | Professional & scientific | 2013 |
| SI Brandon Ltd | Information & communication | 2021 |
| Siaidesign Ltd | Construction | 2025 |
| SIC Building Services Limited | Construction | 2008 |
| Sicodaddy Ltd | Wholesale & retail | 2015 |
| Sidney Dove Limited | Real estate | 2019 |
| Sieve Creative Limited | Arts & recreation | 2014 |
| Sigma Biomass Limited | Agriculture & fishing | 2017 |
| Sigma Building Supplies Limited | Wholesale & retail | 2013 |
| Signals Control UK Limited | Professional & scientific | 2022 |
| Signature House Entertainment Ltd | Arts & recreation | 2026 |
| Signtec Solutions Limited | Manufacturing | 2013 |
| Silva Star Events Ltd | Wholesale & retail | 2022 |
| Silver Needles Studio Limited | Other services | 2018 |
| Silver Spoon Essex Limited | Extraterritorial | 2013 |
| Silverbirch Animal Therapy S.A.T CIC | Agriculture & fishing | 2022 |
| Silverbrix Limited | Real estate | 2019 |
| Silvergate Homes Ltd | Real estate | 2025 |
| Silverswan Holdings Limited | Construction | 2025 |
| Silverswan Services Limited | Construction | 1991 |
| Silverview Square Ltd | Hospitality | 2025 |
| SIM Card Supermarket Limited | Information & communication | 2020 |
| SIM Electrical Ltd | Construction | 2014 |
| SIM Groundwork’S Ltd | Construction | 2025 |