| Shalbourne House RTM Company Limited | Households | 2020 |
| Shannon Structural Design Limited | Professional & scientific | 2012 |
| Shaw-White Estates Limited | Real estate | 1952 |
| Shawdon Homes (Felton RD) Ltd | Construction | 2024 |
| Shawdon Homes (Verity Crescent) Ltd | Real estate | 2025 |
| Shawdon Homes Ltd | Construction | 2018 |
| Sheerin Bettle and Associates Limited | Professional & scientific | 2007 |
| Shelley Manor Apartments Manco. Limited | Households | 2016 |
| Shine Leadership Ltd | Professional & scientific | 2024 |
| Shinytastic Ltd | Information & communication | 2012 |
| Shipyard Estate West Bay Management Limited | Real estate | 1994 |
| Shop Spec UK Limited | Construction | 1994 |
| Shopspec (Holdings) Limited | Professional & scientific | 2006 |
| Shoreacre Freehold Limited | Households | 2008 |
| Shutewater Investments Limited | Real estate | 2018 |
| Silent Dreams Limited | Wholesale & retail | 2020 |
| Silver Travel Service Limited | Transport & logistics | 2019 |
| Silverfox Management Limited | Professional & scientific | 2001 |
| Silverline Environmental Ltd | Professional & scientific | 2023 |
| Silwood Management Company Limited | Households | 2012 |
| Simply Beauty Ringwood Ltd | Other services | 2015 |
| Simply Genius Ltd | Information & communication | 2002 |
| Simply Pleasure Limited | Wholesale & retail | 2001 |
| Simply Shiatsu Ltd | Health & social care | 2008 |
| Sinbar Associates Limited | Construction | 2001 |
| SIR W.G. Armstrong Whitworth & Co. (Engineers) Limited | Professional & scientific | 2021 |
| Sirius Residential Ltd | Real estate | 2025 |
| Siso Software Limited | Information & communication | 2006 |
| Sito Equipment Limited | Wholesale & retail | 2018 |
| Sixty SIX Associates Ltd | Professional & scientific | 2015 |
| Sjbx Ltd | Wholesale & retail | 2025 |
| SJM Family Investment Limited | Professional & scientific | 2020 |
| Skirting Express Limited | Manufacturing | 2015 |
| Slawson Trading Limited | Administrative & support | 1999 |
| Slept Ltd | Financial services | 2024 |
| Slough Town Football Community Club (Stfc) Ltd | Arts & recreation | 2015 |
| Smart Move Ltd | Real estate | 2023 |
| Smartcall Healthcare Ltd | Administrative & support | 2018 |
| Smarter Business Limited | Administrative & support | 2009 |
| Smarter Technologies Group Limited | Professional & scientific | 2019 |
| Smarter Technologies Trading Limited | Information & communication | 2019 |
| Smash Burger FP Limited | Hospitality | 2018 |
| Smith Commercials Limited | Extraterritorial | 2023 |
| Smith Estates Ltd | Real estate | 2013 |
| Smiths Farm Management Company Limited | Households | 2019 |
| SMJ Management Ltd | Real estate | 2026 |
| SMR Legal Ltd | Professional & scientific | 2020 |
| SNK Projects Ltd | Construction | 2022 |
| Snorse Limited | Professional & scientific | 2016 |
| Snowgum Enterprises Limited | Wholesale & retail | 2007 |
| Snuff Court Management Company Limited | Real estate | 2023 |
| Social Savour Ltd | Professional & scientific | 2023 |
| Social Secret Ltd. | Professional & scientific | 2014 |
| Sofa & More Ltd | Wholesale & retail | 2011 |
| Soft Play in a Box Ltd | Arts & recreation | 2025 |
| Solar Service Solutions Ltd | Construction | 2022 |
| Solent Staff Fire Training Limited | Education | 2008 |
| Solutionsnet Limited | Information & communication | 1997 |
| Somerley Energy Limited | Energy | 2015 |
| Somersetwarmroofs Limited | Administrative & support | 2017 |
| Sonda Studios Media Ltd | Information & communication | 2026 |
| Sophat Studio Ltd | Administrative & support | 2024 |
| Sophia Medical Limited | Professional & scientific | 2014 |
| SOS Band Ltd | Information & communication | 2026 |
| Soul SIP Collective Ltd | Hospitality | 2025 |
| Soulful Cleaning Commercial Ltd | Administrative & support | 2025 |
| Sounds Beautiful Ltd | Hospitality | 2023 |
| South Bucks Hospice | Health & social care | 2008 |
| South Coast Clinical Solutions Limited | Health & social care | 2022 |
| South Coast Fabrications Limited | Professional & scientific | 2007 |
| South Coast Lettings Ltd | Real estate | 2025 |
| South Coast Network Limited | Information & communication | 2014 |
| South Coast Sports Ltd | Education | 2026 |
| South Heating Solutions Ltd | Construction | 2024 |
| Southbourne School of English Limited | Education | 1982 |
| Southern Car Storage Ltd | Real estate | 2012 |
| Southern Horticulture Limited | Agriculture & fishing | 2013 |
| Southern Plant & Renewables Limited | Agriculture & fishing | 2023 |
| Southern Psychology Services Ltd | Education | 2021 |
| Southern Retail Systems Limited | Administrative & support | 2010 |
| Southstage Productions Ltd | Arts & recreation | 2024 |
| Sovereign Carpets (Burnham) Limited | Wholesale & retail | 2009 |
| Sparkling Spas Ltd. | Wholesale & retail | 2016 |
| Sparksluxe Holdings Limited | Financial services | 2025 |
| Sparta Construction Ltd | Water & waste | 2019 |
| Specialised Flooring Solutions Ltd | Construction | 2010 |
| Spectframe Limited | Information & communication | 2025 |
| Speedi Tyres Ltd | Wholesale & retail | 2025 |
| Speltham Contracts Limited | Construction | 1961 |
| Spencer James New Forest Limited | Real estate | 2020 |
| Spencers Lettings (Wimborne) Ltd | Real estate | 2010 |
| Spencers Lettings Limited | Real estate | 2008 |
| Spencers of Lymington Limited | Real estate | 2013 |
| Spencers of Ringwood Limited | Real estate | 2010 |
| Spencers of the New Forest Limited | Real estate | 2010 |
| Spencers Property Group Ltd | Financial services | 2026 |
| Spinnaker Sailing Club Ltd | Arts & recreation | 2014 |
| SPM Plumbing and Heating Limited | Construction | 2014 |
| Spoilt Rotten Embroidery Limited | Wholesale & retail | 2011 |
| Sport 101 Ltd | Arts & recreation | 2014 |