| Sandon Road Limited | Households | 2014 |
| Sandown Court (Southport) Limited | Households | 1977 |
| Sandringham (1-11) RTM Company Limited | Households | 2024 |
| Sandringham (Lord ST) RTM Company Ltd | Households | 2025 |
| Sandringham Court Management Company (Southport) Limited | Households | 2016 |
| Sandy's Cleaning Services Limited | Households | 2014 |
| Sansoon Ltd | Health & social care | 2024 |
| Santa's Competition Limited | Education | 2025 |
| Santa's Forest Ltd | Arts & recreation | 2022 |
| Sara B Caul Landscapes Ltd | Administrative & support | 2024 |
| Sarah Lapsley Law Limited | Professional & scientific | 2019 |
| SAS FIC Ltd | Financial services | 2023 |
| Saunders Street Management Company Ltd. | Real estate | 2011 |
| Savvyserve Ltd | Information & communication | 2013 |
| Saxenholme Flat Management (Southport) Limited | Households | 1990 |
| Saxon Lodge Limited | Households | 1974 |
| Saxton Property Ltd | Real estate | 2024 |
| SB Reliability Ltd | Professional & scientific | 2022 |
| SB Surgical Ltd | Health & social care | 2023 |
| SBJ Builders Ltd | Construction | 2022 |
| SC Properties Southport Ltd | Real estate | 2022 |
| Scaffolding Specialists Ltd | Administrative & support | 2025 |
| Scalable MSP Ltd | Professional & scientific | 2022 |
| Scamp Publishing Limited | Information & communication | 2021 |
| Scan IT Store IT UK Ltd | Information & communication | 2022 |
| Scarfire Safety Ltd | Public administration | 2023 |
| Scarisbrick Avenue Ltd | Hospitality | 2019 |
| Scarisbrick Bowling Club Limited | Arts & recreation | 1932 |
| Scarisbrick Nurseries Plant Centre Ltd | Agriculture & fishing | 2004 |
| Scarlett Red Ltd | Administrative & support | 2018 |
| SCC (Southport) Ltd | Wholesale & retail | 2009 |
| Scholars Gate (Haskayne) Management Company Limited | Households | 2012 |
| School Hair Accessories UK Ltd | Wholesale & retail | 2023 |
| Schultz Medical (UK) Ltd | Manufacturing | 2014 |
| Scissors Ltd | Other services | 2019 |
| SCN Advisory Limited | Other services | 2022 |
| Scoop Dotty Dog Limited | Water & waste | 2015 |
| Scope KIT Limited | Information & communication | 2025 |
| Scott Developments Southport Ltd | Real estate | 2026 |
| Scott Landscapes (Southport) Ltd | Construction | 2023 |
| Scott Reay Ltd | Transport & logistics | 2014 |
| Scottie Press C.I.C. | Information & communication | 2018 |
| Sdcgnw Ltd | Construction | 2024 |
| SDD Express Logistics Ltd | Transport & logistics | 2025 |
| Sea Audio Visual Ltd | Information & communication | 2012 |
| Sea Palace Southport Limited | Hospitality | 2017 |
| Seafront Catering Services Limited | Hospitality | 1996 |
| Seamless Micro Cement Ltd | Construction | 2024 |
| Seapoint Court Flat Management (Southport) Limited | Households | 1987 |
| Seascope Design Limited | Professional & scientific | 2004 |
| Season Coffee, Bar & Kitchen Ltd | Hospitality | 2019 |
| Seaview Guest House Southport Ltd | Hospitality | 2025 |
| Seawest Flat Management (Southport) Limited | Professional & scientific | 1986 |
| Seccomms Ltd | Information & communication | 2026 |
| Seconds Count Limited | Arts & recreation | 2004 |
| Secrha (UK) Ltd | Wholesale & retail | 2022 |
| Sector Associates Ltd | Financial services | 2017 |
| Secure Management MCR Ltd | Water & waste | 2011 |
| Secure My Door UK Ltd | Construction | 2020 |
| Secure Research Limited | Wholesale & retail | 2026 |
| Securetheting Ltd | Real estate | 2022 |
| Seear Ltd | Information & communication | 2023 |
| Seen in Southport Ltd | Professional & scientific | 2026 |
| Sefton & Merseyside Senior Care Services Limited | Health & social care | 2007 |
| Sefton Advocacy | Health & social care | 2002 |
| Sefton CU Trust | Education | 2011 |
| Sefton Homecare & Cleaning Ltd | Administrative & support | 2025 |
| Sefton Lettings Ltd | Real estate | 2025 |
| Sefton Pride CIC | Education | 2023 |
| Sefton Windows & Plastics Ltd | Construction | 2021 |
| Selby Lesson Limited | Real estate | 1963 |
| Select Car Rentals (North-West) Limited | Administrative & support | 1994 |
| Select Cards, Gifts and Art Ltd | Extraterritorial | 2015 |
| Select Comps Ltd | Arts & recreation | 2025 |
| Select Office Supplies & Business Equipment Limited | Wholesale & retail | 1987 |
| Sensigence Limited | Professional & scientific | 2025 |
| Sensus Invista Ltd | Information & communication | 2025 |
| Serge Nugent Properties Ltd | Real estate | 2019 |
| Serica Developments Ltd | Real estate | 2025 |
| Service and Tyre Cetre Ltd | Professional & scientific | 2022 |
| Servisolutions Limited | Construction | 2009 |
| SES House Holdings Ltd | Financial services | 2020 |
| Sesom Properties Ltd | Real estate | 2017 |
| Settle Leisure Limited | Wholesale & retail | 2010 |
| SEW IT Begins Limited | Extraterritorial | 2019 |
| Sexual Health Logistics Limited | Administrative & support | 2007 |
| SFJ1 Ltd | Households | 2023 |
| Sfta Ltd | Health & social care | 2023 |
| SG Design & Print Ltd | Manufacturing | 2016 |
| SG Mobile Butchers Ltd | Wholesale & retail | 2020 |
| SGB Projects Limited | Construction | 2013 |
| SGC Painters and Decorators Limited | Construction | 2024 |
| Sgdp Solution Limited | Administrative & support | 2025 |
| SGN & SON Ltd | Professional & scientific | 2011 |
| Sgssouthport Ltd | Wholesale & retail | 2023 |
| SH Eagle Construction Ltd | Construction | 2021 |
| Shahi Properties (NW) Limited | Real estate | 2023 |
| Shaju Properties Ltd | Real estate | 2025 |
| Shallom Healthcare Ltd | Health & social care | 2014 |
| Shamraat Ltd | Hospitality | 2015 |