| Sheds Direct NI Limited | Construction | 2021 |
| Sheehy Consulting Ltd | Professional & scientific | 2013 |
| Shelter TEC Ltd | Wholesale & retail | 2024 |
| Shield Accident Management Ltd | Other services | 2018 |
| Shields Mortgage Services Ltd | Financial services | 2004 |
| Shopmobility MID Ulster | Health & social care | 2016 |
| Shore Fibre Comms Limited | Construction | 2020 |
| Shritech Ltd | Professional & scientific | 2026 |
| Sign Properties Services Limited | Real estate | 2014 |
| Sign Reload Limited | Manufacturing | 2014 |
| Sika Contract Holdings Ltd | Financial services | 2020 |
| Silo Spares Ltd | Manufacturing | 2019 |
| Silvercirkel Limited | Professional & scientific | 2018 |
| Silvercity Limited | Construction | 2015 |
| Silverford Aviation Ltd | Transport & logistics | 2017 |
| Silverford Engineering Ltd | Professional & scientific | 2016 |
| Silverford Holdings Ltd | Professional & scientific | 2016 |
| Silverford Property Ltd | Construction | 2016 |
| Silverford Wind 1 Ltd | Energy | 2016 |
| Silverford Wind 2 Ltd | Energy | 2016 |
| Silverford Wind 3 Ltd | Energy | 2017 |
| Simple Scaling Ltd | Professional & scientific | 2020 |
| Sinergy Tile & Bathroom Ltd | Wholesale & retail | 2019 |
| Single Source Systems Ltd | Manufacturing | 2020 |
| Sinnamon Holdings Limited | Professional & scientific | 2025 |
| Sinnamons Stores (Aghalee) Limited | Wholesale & retail | 2020 |
| Sinnamons Stores Limited | Wholesale & retail | 2014 |
| SJ Davidson Motors Ltd | Wholesale & retail | 2006 |
| SJ Wylie Holdings Limited | Financial services | 2018 |
| SJOD5 Ltd | Real estate | 2025 |
| SK Clarke Transport Ltd | Transport & logistics | 2022 |
| SK Consulting Services Ltd | Information & communication | 2023 |
| Skand House Limited | Financial services | 2023 |
| Skeffington & Co. (NI) Ltd | Real estate | 2023 |
| SKM Freight Ltd | Transport & logistics | 2026 |
| Skrecruitmentagency Ltd | Administrative & support | 2016 |
| Skullion Bros Ltd | Manufacturing | 2013 |
| Skye Body Repair Limited | Wholesale & retail | 2016 |
| Skyhill Parks Limited | Construction | 2024 |
| Skyshield Roofing and Services Ltd | Construction | 2026 |
| Skytask Aerial Imaging Ltd | Administrative & support | 2015 |
| Slate Quarry Farms Limited | Agriculture & fishing | 2012 |
| Slate Quarry Specialist Systems Ltd | Wholesale & retail | 2023 |
| Slate Trading Ltd | Transport & logistics | 2015 |
| Slatequarry Construction Ltd | Construction | 2021 |
| Slatequarry Development Association Ltd | Arts & recreation | 2010 |
| SLC Distribution Ltd | Wholesale & retail | 2022 |
| Sldj Investments Limited | Real estate | 2025 |
| Sloan Street Vehicle Repairs Ltd | Wholesale & retail | 2019 |
| Slogie Limited | Information & communication | 2024 |
| Sluggan Farms Limited | Agriculture & fishing | 2014 |
| Slushee Export LLP | | 2007 |
| Slushee Trading Partners Ltd | Wholesale & retail | 2015 |
| SM Aesthetics Ltd | Health & social care | 2018 |
| SM Cushnahan Engineering Ltd | Manufacturing | 2016 |
| SM USA Scholarships Limited | Arts & recreation | 2021 |
| Smak Properties Limited | Real estate | 2006 |
| Smart HRV Ltd | Manufacturing | 2024 |
| SMC Contracts Ltd | Construction | 2004 |
| Smca 2024 Limited | Construction | 2024 |
| Smca Properties Limited | Real estate | 2019 |
| Smcc Montaigh Ltd | Real estate | 2023 |
| SMG Mechanical Ltd | Construction | 2025 |
| SMK Control Ltd | Manufacturing | 2020 |
| SMP Concrete Products Ltd | Manufacturing | 2011 |
| Snaght Limited | Financial services | 2023 |
| Snarg Ltd | Real estate | 2017 |
| SNL (NI) Limited | Wholesale & retail | 2013 |
| Snooty FOX Boutique Limited | Wholesale & retail | 2023 |
| Snow Media Limited | Information & communication | 2015 |
| Soap Armagh Ltd | Financial services | 2024 |
| Soap Enterprise Ltd | Financial services | 2024 |
| SOD1 Ltd | Real estate | 2023 |
| SOE Haulage Ltd | Transport & logistics | 2010 |
| Solartek Energy Limited | Other services | 2024 |
| Solo Shoes Ltd | Wholesale & retail | 2021 |
| Sonic Lifts Limited | Manufacturing | 2018 |
| Souse Developments Ltd | Construction | 2006 |
| South and East Tyrone Welfare Support | Extraterritorial | 2013 |
| South Lough Neagh Regeneration Association | Other services | 2005 |
| South Tyrone Commercials Limited | Wholesale & retail | 2024 |
| South Tyrone Empowerment Programme | Education | 1999 |
| Sovereign Properties (NI) Limited | Real estate | 1988 |
| Spares OR Repairs Ltd | Other services | 2025 |
| SPC Components NI Ltd | Professional & scientific | 2019 |
| Spec-Drum Engineering | Manufacturing | 2003 |
| Specdrum Limited | Manufacturing | 2016 |
| Specfab Limited | Manufacturing | 2021 |
| Speciality Mushrooms Limited | Manufacturing | 2014 |
| SPG Enterprises Ltd | Hospitality | 2020 |
| Spiros Poker Ltd | Manufacturing | 2004 |
| SPM Modular Solutions Ltd | Construction | 2025 |
| Sportec Fitness Ltd | Arts & recreation | 2016 |
| Spos Property Limited | Real estate | 2025 |
| Spraytex Ltd | Construction | 2022 |
| Sprick Healthcare Limited | Health & social care | 2023 |
| Spring Property Developments Ltd | Construction | 2019 |
| Springisland Property Limited | Real estate | 2022 |
| Springwell Renewables Ltd | Water & waste | 2013 |
| Square Cabins Ltd | Manufacturing | 2019 |