| SITECRE8R Ltd | Information & communication | 2015 |
| Sitepics Ltd | Information & communication | 2023 |
| Sivik Active CIC | Other services | 2021 |
| SIX Days Consultancy Limited | Professional & scientific | 2024 |
| SIX2 PVT Limited | Wholesale & retail | 2025 |
| Sixone Limited | Information & communication | 2023 |
| Sizzlers Online (York) Limited | Hospitality | 2023 |
| Sizzlers Takeaway (York) Limited | Hospitality | 2023 |
| SJ Oris Solutio Ltd | Health & social care | 2015 |
| SJB Development Ltd | Other services | 2006 |
| SJB Holdings (Yorkshire) Ltd | Financial services | 2022 |
| SJC Enabling Improvements Ltd | Professional & scientific | 2012 |
| Sjc@Consulting Limited | Professional & scientific | 2018 |
| SJH Equestrian Limited | Arts & recreation | 2020 |
| SJS Property Solutions Ltd | Real estate | 2021 |
| SK Unique Studio Ltd | Other services | 2026 |
| Skanglow Limited | | 1981 |
| Skelton Adventures Limited | Hospitality | 2022 |
| Skelton Heritage Estates Limited | Real estate | 2025 |
| Skelton Shop Ltd | Wholesale & retail | 2026 |
| Skewkirk Farming Limited | Agriculture & fishing | 1986 |
| Skiff Lane 2005 Ltd | Real estate | 2005 |
| Skills 4 Holme Ltd | Health & social care | 2012 |
| Skillsforge Holdings Limited | Financial services | 2021 |
| Skillsforge Ltd | Information & communication | 2013 |
| Skillsmith Electrical Services Limited | Construction | 2017 |
| Skillsmith Property Holdings Limited | Real estate | 2022 |
| Skin and Laser Medical Limited | Health & social care | 2023 |
| Skin Tech Clinic Ltd | Health & social care | 2017 |
| Skincare Group Ltd | Financial services | 2023 |
| Skinfade Factory Limited | Other services | 2023 |
| Skinotive Studio Ltd | Other services | 2023 |
| Skinstudioyork Ltd | Health & social care | 2023 |
| Skipbridge Country Weddings Ltd | Hospitality | 2020 |
| Skipbridge Farm Events Ltd | Other services | 2020 |
| Skipbridge Farm Kitchen Ltd | Hospitality | 2021 |
| Skipbridge Farm Tipi Hire Ltd | Administrative & support | 2020 |
| Skirmish Group Limited | Financial services | 2022 |
| Skiweb Limited | Information & communication | 1998 |
| SKM Investments Limited | Real estate | 2020 |
| SKO Consulting Limited | Professional & scientific | 2011 |
| Skoroflow Limited | Information & communication | 2025 |
| Skosh (York) Limited | Hospitality | 2014 |
| SKR Medical Ltd | Health & social care | 2014 |
| Skrav Limited | Real estate | 2026 |
| SKU Storage & Display Solutions Ltd | Administrative & support | 2023 |
| Sky Blue Legal Limited | Professional & scientific | 2023 |
| Sky Blue York Ltd. | Hospitality | 2021 |
| Sky Duthie Rare Books Limited | Wholesale & retail | 2022 |
| Sky Filming Ltd | Information & communication | 2015 |
| Sky Retail Services Ltd | Wholesale & retail | 2022 |
| Sky World Adventures Ltd | Arts & recreation | 2026 |
| Skyblue I T Limited | Wholesale & retail | 2008 |
| Skyblue Research Ltd | Professional & scientific | 2007 |
| Skybluesteve Limited | Professional & scientific | 2008 |
| Skyboard Aerobatics Limited | Other services | 2006 |
| Skyboard Group Ltd | Financial services | 2026 |
| Skye Associates Limited | Professional & scientific | 2019 |
| Skyfilms Limited | Wholesale & retail | 2012 |
| Skyhunter Global Ltd | Professional & scientific | 2020 |
| Skyline Properties & Development Limited | Wholesale & retail | 2021 |
| SKZ Holdings Ltd | Real estate | 2021 |
| SL Sunshine Ltd | Hospitality | 2021 |
| SLA Trading Ltd. | Wholesale & retail | 2005 |
| Slab Trader Ltd | Extraterritorial | 2023 |
| Slater Dental Limited | Health & social care | 2025 |
| Slater Energy Ltd | Professional & scientific | 2015 |
| Slaven Consultancy Services Ltd | Professional & scientific | 2016 |
| SLB Construction Management Limited | Extraterritorial | 1986 |
| SLC Motor Holdings Ltd | Financial services | 2025 |
| SLD Construction York Ltd | Construction | 2013 |
| SLD Holdings Limited | Real estate | 2022 |
| Sleepline UK Limited | Manufacturing | 2011 |
| Sleepvendor Products Limited | Manufacturing | 2011 |
| Sleights Limited | Professional & scientific | 2013 |
| Slen Events Ltd | Transport & logistics | 2024 |
| Slice Twenty SIX Ltd | Hospitality | 2022 |
| Slide North Ltd | Professional & scientific | 2023 |
| Slide-Ruler Ltd | Wholesale & retail | 2008 |
| Slim With Corinne Ltd | Health & social care | 2024 |
| Slipstone Limited | Professional & scientific | 2017 |
| Slipstreamdata Ltd | Information & communication | 2026 |
| Slme Propertys Ltd | Real estate | 2026 |
| Sloemotion Distillery Limited | Manufacturing | 2006 |
| Sloop 2018 Ltd | Hospitality | 2018 |
| Slurp Ltd | Information & communication | 2025 |
| SM Market Trader Limited | Wholesale & retail | 2025 |
| SM Motorsport Services Limited | Arts & recreation | 2023 |
| SM Services Yorkshire Limited | Manufacturing | 2019 |
| Small Measures Ltd | Professional & scientific | 2018 |
| Smalldale Developments Limited | Construction | 2023 |
| Smalley Property Investments Limited | Real estate | 2021 |
| Smart (York) Limited | Professional & scientific | 2018 |
| Smart Business Services Ltd | Professional & scientific | 2015 |
| Smart Cleaning Group Limited | Administrative & support | 2015 |
| Smart E-Bikes Ltd | Wholesale & retail | 2020 |
| Smart Franchising Limited | Administrative & support | 2020 |
| Smart Hosting Limited | Information & communication | 2007 |
| Smart Lettings (York) Ltd | Real estate | 2025 |
| Smart Planet Limited | Professional & scientific | 2020 |