| Sefton O.P.E.R.A. | Health & social care | 1999 |
| Sefton Surfacing Limited | Construction | 2014 |
| Seguro Care Services Ltd | Administrative & support | 2021 |
| Seguro Recruitment Ltd | Administrative & support | 2020 |
| Seguro Training Ltd | Extraterritorial | 2024 |
| Select Pilates Ltd | Other services | 2024 |
| Semunait Local Store Ltd | Wholesale & retail | 2026 |
| Senduback Ltd | Transport & logistics | 2025 |
| Senior Fabrication & Welding Services Ltd | Manufacturing | 2018 |
| Sequoia Estates Limited | Construction | 2013 |
| Serene Care Group Northwest Ltd | Health & social care | 2025 |
| Service Electrical Distributors Ltd | Wholesale & retail | 2019 |
| Sesay's Bar & Grill Limited | Hospitality | 2020 |
| Sevara Limited | Wholesale & retail | 2026 |
| SGK1 Ltd | Wholesale & retail | 2023 |
| Shadow Projects Ltd | Arts & recreation | 2015 |
| Shahjalal Takeaway Limited | Hospitality | 2019 |
| Sharp Anaesthesia Limited | Health & social care | 2025 |
| Shepclothing Ltd | Wholesale & retail | 2025 |
| Shiiv Property Ltd | Real estate | 2024 |
| Shoemaster Ltd | Other services | 2022 |
| Shredsafe Secure Limited | Water & waste | 2011 |
| Shunfa Construction Ltd | Wholesale & retail | 2024 |
| Shush Doors Ltd | Wholesale & retail | 2015 |
| Silder Trade Ltd | Wholesale & retail | 2020 |
| Silver-Circle Companions Limited | Health & social care | 2026 |
| Silverback MCS Limited | Professional & scientific | 2023 |
| Silvtansa Ltd | Health & social care | 2024 |
| Simon Art Ltd | Wholesale & retail | 2023 |
| Simply Natal CIC | Health & social care | 2025 |
| Simply Thai Massage Limited | Health & social care | 2026 |
| Sister Lash Ltd | Wholesale & retail | 2025 |
| SJH Accountancy Services Ltd | Professional & scientific | 2011 |
| SJK Aesthetics Ltd | Health & social care | 2025 |
| Skiano Solution Limited | Wholesale & retail | 2026 |
| Skin Deep Clinics and Academy Ltd | Education | 2026 |
| Skyland News Ltd | Wholesale & retail | 2022 |
| Slawomir Janik Transport Ltd. | Transport & logistics | 2015 |
| Sleekblueprint Ltd | Information & communication | 2026 |
| Slopol Distribution Ltd | Wholesale & retail | 2026 |
| Slopol Transport Ltd. | Transport & logistics | 2018 |
| SM Holdings Merseyside Limited | Households | 2020 |
| Small Vault Ltd | Hospitality | 2025 |
| Smart Clean Solution Ltd | Administrative & support | 2025 |
| Smarter Business Energy Limited | Professional & scientific | 2018 |
| Smith & Jones Properties Limited | Administrative & support | 2012 |
| Smith-Hughes Consulting Limited | Health & social care | 2013 |
| SMK Trans Ltd | Transport & logistics | 2017 |
| SML Hub CIC | Education | 2025 |
| SMX Investments Ltd | Real estate | 2024 |
| Society for Public Architecture Construction Engineering and Surveying Ltd | Professional & scientific | 1990 |
| Softserv UK Ltd | Wholesale & retail | 2023 |
| Soge Consultancy Ltd | Professional & scientific | 2026 |
| SOL Foods Limited | Transport & logistics | 2011 |
| Solok Group Ltd | Wholesale & retail | 2026 |
| Solve Analytics Limited | Administrative & support | 2024 |
| Sonhos Property Limited | Real estate | 2026 |
| SOR Brickwork Ltd | Construction | 2019 |
| SOR Property Group Ltd | Real estate | 2025 |
| Soul Trade Ltd | Administrative & support | 2020 |
| Souliee Ltd | Wholesale & retail | 2026 |
| South Sefton Development Trust | Administrative & support | 2004 |
| South Sefton Primary Healthcare Ltd | Health & social care | 2017 |
| Sovini Commercial Limited | Manufacturing | 2012 |
| Sovini Construction Limited | Construction | 1999 |
| Sovini Developments Limited | Construction | 2012 |
| Sovini Environmental Limited | Administrative & support | 2012 |
| Sovini Homes Limited | Construction | 2012 |
| Sovini Land Acquisition Limited | Financial services | 2013 |
| Sovini Property Services Limited | Construction | 2010 |
| Sovini Trade Supplies Limited | Wholesale & retail | 2014 |
| Sovini Waste Solutions Limited | Water & waste | 2011 |
| SP Mago Ltd | Wholesale & retail | 2026 |
| SP Print Limited | Manufacturing | 2024 |
| Spaima Ltd | Wholesale & retail | 2017 |
| Spark Digital Learning Solutions Limited | Information & communication | 2026 |
| Spartacus Experience Limited | Education | 2022 |
| Spartacus XP Ltd | Education | 2025 |
| SPC Heating and Maintenance Ltd | Construction | 2026 |
| SPD Group NW Ltd | Construction | 2015 |
| SPD Investment Group Ltd | Real estate | 2016 |
| Specialised Group Limited | Construction | 2016 |
| Specialist Support Systems Ltd | Construction | 2025 |
| SPL Transport Limited | Education | 2007 |
| Sports and Health Limited | Wholesale & retail | 2020 |
| Spotmix Ready Mixed Concrete Ltd | Administrative & support | 2015 |
| Spray Colour UK Ltd | Construction | 2026 |
| Springtime Solutions International Ltd | Manufacturing | 2024 |
| Sprout Management Ltd | Wholesale & retail | 2025 |
| Square Installation UK Ltd | Construction | 2022 |
| Srks Construction Ltd | Construction | 2025 |
| SS Access & Maintenance Ltd | Construction | 2018 |
| SSI Global Logistics Ltd | Transport & logistics | 2025 |
| SSS Scaffolding Group UK Limited | Construction | 2026 |
| Sssf Limited | Construction | 2024 |
| ST. Leonard's Youth & Community Centre | Arts & recreation | 2008 |
| Stad Property Ltd | Real estate | 2026 |
| Stamps Brewery Limited | Manufacturing | 2016 |
| Stanley Fast Food Bootle Ltd | Hospitality | 2025 |
| Stanley Wadham Properties Limited | Real estate | 2015 |