| Siroflex Limited | Wholesale & retail | 1993 |
| SIS (Yorkshire) Limited | Wholesale & retail | 2014 |
| Site Decommissioning Solutions Ltd | Construction | 2010 |
| Site Lynx Group Ltd | Information & communication | 2026 |
| Sithandazile Maphosa Ltd | Public administration | 2024 |
| SIX Apple Yard Limited | Other services | 2009 |
| Sixteen Sixty SIX Limited | Professional & scientific | 2023 |
| SIXTEEN60 Ltd | Professional & scientific | 2023 |
| SJ and Sons Properties Limited | Real estate | 2025 |
| SJ Solutions Consultancy Limited | Professional & scientific | 2023 |
| SJL Group Ltd | Financial services | 2018 |
| SJM Building Services(Chapeltown) Ltd | Construction | 2014 |
| SJQ Limited | Extraterritorial | 2008 |
| SJW Decorators Limited | Construction | 2007 |
| SJY Fencing & Projects Ltd | Construction | 2025 |
| SK Building & Surfacing Ltd | Construction | 2016 |
| SK GAS and Stoves Limited | Construction | 2015 |
| SK Great Properties Ltd | Real estate | 2022 |
| Skanex Limited | Wholesale & retail | 2005 |
| Skate & Bake Ltd | Wholesale & retail | 2026 |
| Skeats Safeguarding Consultancy Ltd | Professional & scientific | 2024 |
| SKH Plant Services Limited | Construction | 2004 |
| Skiba Limited | Transport & logistics | 2026 |
| Skill-Forge Esports Academy Ltd | Arts & recreation | 2025 |
| Skills UA CIC | Education | 2025 |
| SKILLS4EBUSINESS.COM | Administrative & support | 2009 |
| Skin by Hartley Limited | Other services | 2021 |
| Skin LAB Aesthetics & Skin Rejuvenation Ltd | Health & social care | 2021 |
| Skinderma Pro Ltd | Education | 2017 |
| Skip and Grab Hire Ltd | Transport & logistics | 2025 |
| SKN Transport Ltd | Transport & logistics | 2025 |
| SKT Pubs Ltd | Hospitality | 2025 |
| Skull With Cigarette Limited | Manufacturing | 2024 |
| Sky Marmot Limited | Wholesale & retail | 2023 |
| Sky Weddings Ltd | Information & communication | 2021 |
| Skye Surplus Ltd | Wholesale & retail | 2023 |
| Skyie Healthcare Limited Limited | Health & social care | 2024 |
| Skyla's POP Kitchen UK Ltd | Hospitality | 2015 |
| Skyline 2020 Ltd | Transport & logistics | 2023 |
| Skystarpubs (Cross Keys) Ltd | Hospitality | 2020 |
| Skystarpubs (Sportsman) Ltd | Hospitality | 2019 |
| Skystarpubs Limited | Hospitality | 2019 |
| Skytech Inspection Ltd | Construction | 2020 |
| SL & L Holdings Limited | Transport & logistics | 2015 |
| Slab City TCG Ltd | Wholesale & retail | 2026 |
| Slashdot Studios Limited | Professional & scientific | 2017 |
| SLC Consulting Ltd | Professional & scientific | 2025 |
| SLD Property Limited | Real estate | 2016 |
| SLD Solutions & Design Ltd | Professional & scientific | 2025 |
| SLG Recovery Breakdown Ltd | Transport & logistics | 2025 |
| Slice Pizzeria Limited | Hospitality | 2025 |
| Slickbevs Limited | Hospitality | 2023 |
| Sliders Wardrobes Limited | Manufacturing | 2019 |
| Slim Lion Ltd | Real estate | 2017 |
| Slime Party UK Limited | Manufacturing | 2018 |
| SLJ Mortgage Broker Ltd | Financial services | 2018 |
| Slom Trading Ltd | Wholesale & retail | 2021 |
| SLS Coatings Limited | Administrative & support | 2013 |
| SLW Yorkshire Ltd | Hospitality | 2023 |
| SM Electrical Yorkshire Ltd | Construction | 2020 |
| SM Golf Coaching Ltd | Arts & recreation | 2021 |
| Smart Contracts (Yorkshire) Limited | Wholesale & retail | 2009 |
| Smart Door Solutions Limited | Manufacturing | 2014 |
| Smart Hvac Limited | Construction | 2018 |
| Smart Interiors Joinery Contractors Limited | Construction | 2016 |
| Smart Line Furniture Ltd. | Wholesale & retail | 2010 |
| Smart Renewables & Heating Ltd | Construction | 2023 |
| Smart Rentalz Limited | Real estate | 2021 |
| Smart Trax Electrical Limited | Construction | 2018 |
| Smart Trax Limited | Construction | 2017 |
| Smart Trax Property Limited | Real estate | 2021 |
| Smart Water Utilities Limited | Construction | 2015 |
| Smart's Transport Ltd | Transport & logistics | 2020 |
| Smartdec Limited | Wholesale & retail | 2025 |
| Smartecowindows Limited | Construction | 2024 |
| Smarter Rentals Ltd | Real estate | 2019 |
| Smarter Training & Consultancy Limited | Professional & scientific | 2007 |
| Smartovations Ltd | Manufacturing | 2019 |
| Smartstyle Technology Training Limited | Information & communication | 1999 |
| Smarttech Security Solutions Ltd | Administrative & support | 2020 |
| Smartways Automotive Smart Repair Ltd | Wholesale & retail | 2021 |
| Smartwire Technologies Ltd | Information & communication | 2026 |
| Smarty Global Ltd | Professional & scientific | 2025 |
| Smartz Recruitment Limited | Administrative & support | 2013 |
| SMASHHUB71 Ltd | Hospitality | 2024 |
| SMC Agencies Limited | Administrative & support | 2002 |
| SMC Housing and Property Ltd | Real estate | 2025 |
| SMD Healthcare Limited | Health & social care | 2021 |
| Smilesafe Holdings Limited | Financial services | 2025 |
| Smilesafe Limited | Health & social care | 2024 |
| Smilesafe Warranties Limited | Health & social care | 2025 |
| Smiley Transport Ltd | Transport & logistics | 2019 |
| Smith & Brown Contractors Ltd | Construction | 2025 |
| Smith Austin Limited | Professional & scientific | 2010 |
| Smith Bros Roofing Ltd | Construction | 2025 |
| Smith Brothers (Contracting) Limited | Construction | 1999 |
| Smith Stone Company Limited | Manufacturing | 2003 |
| Smiths Enginee Soultions Ltd | Manufacturing | 2025 |
| Smiths Surveyors (Barnsley) Limited | Real estate | 2003 |
| Smithy Green Management Company Limited | Households | 2003 |