| Setanta Ltd | Construction | 2002 |
| Seven Electrical Services Limited | Construction | 2025 |
| Sg&Aj Holdings Ltd | Financial services | 2025 |
| Shadbolt Doors Limited | Manufacturing | 2024 |
| Shaftworks Ltd | Wholesale & retail | 2025 |
| Sharman D. Neill Limited | Manufacturing | 1961 |
| Shepherd's Ireland Limited | Hospitality | 2008 |
| Shieldx Compliance Ltd | Water & waste | 2025 |
| Shipping and Compliance Ltd | Transport & logistics | 2026 |
| Shore Road Logistics Ltd | Transport & logistics | 2017 |
| Shrewd Sports Limited | Arts & recreation | 2021 |
| Signtime (N.I.) Limited | Manufacturing | 2016 |
| Silverson Limited | Hospitality | 2018 |
| SIX Dance Collective Ltd | Arts & recreation | 2023 |
| Sixtowns Cross Community Group Ltd | Arts & recreation | 1999 |
| SJS (2000) Ltd | Wholesale & retail | 1999 |
| Skillful Pass Limited - the | Professional & scientific | 2000 |
| Skin (NI) Limited | Health & social care | 2022 |
| Skompa Limited | Professional & scientific | 2018 |
| Skyritzy Ltd | Wholesale & retail | 2022 |
| Slieve Gallion Community Pre-School | Other services | 2007 |
| Slieve Gallion Finance Ltd | Financial services | 2023 |
| Smart Garden Rooms Ltd | Construction | 2022 |
| Smart Homes (N.I.) Ltd | Information & communication | 2021 |
| Smart Lock Storage Limited | Administrative & support | 2026 |
| SMD Renewable Solutions Ltd | Construction | 2024 |
| SMG Pro Spray Ltd | Other services | 2024 |
| Sofood Consultancy Limited | Hospitality | 2016 |
| Sortimo Station NI Ltd | Wholesale & retail | 2025 |
| SOS Joinery Limited | Construction | 2010 |
| Spatialysed Solutions Ltd | Information & communication | 2024 |
| SPB Worldwide Limited | Administrative & support | 2025 |
| Speakeazy Ltd | Extraterritorial | 2017 |
| Specialist Concrete Solutions Ltd | Construction | 2021 |
| Specialist Drilling Services (NI) Ltd | Construction | 2000 |
| SPECTOR33 Ltd | Financial services | 2021 |
| Sperrin Architecture Ltd | Professional & scientific | 2016 |
| Sperrin Consulting Ltd | Information & communication | 2026 |
| Sperrin Drilling Ltd | Construction | 2025 |
| Sperrin Electrical Limited | Construction | 2024 |
| Sperrin Energy Limited | Extraterritorial | 2014 |
| Sperrin Group Limited | Administrative & support | 2024 |
| Sperrin Holdings Limited | Professional & scientific | 1980 |
| Sperrin Metal Holdings Limited | Financial services | 2025 |
| Sperrin Metal Storage Solutions Ltd | Extraterritorial | 2025 |
| Sperrin Network Services Limited | Construction | 2022 |
| Sperrin Powder Coatings Ltd | Extraterritorial | 2025 |
| Sperrin Power Ltd | Energy | 2025 |
| Sperrin Racking Supplies Ltd | Extraterritorial | 2025 |
| Sperrin Retail Ltd | Hospitality | 2016 |
| Sperrin Switchgear Ltd | Manufacturing | 1996 |
| Sperrin Utilities Ltd | Construction | 2022 |
| Sperrins Well Walk Limited | Health & social care | 2021 |
| Sphereops Limited | Information & communication | 2015 |
| Splash (Ireland) Ltd | Arts & recreation | 2019 |
| Spoilt Belle Boutique Limited | Wholesale & retail | 2015 |
| Springhill Trading (Ireland) Limited | Transport & logistics | 2018 |
| SQ Contracts Ltd | Construction | 2014 |
| SQ Electrical Ltd | Construction | 2026 |
| Sqzlgs Limited | Wholesale & retail | 2024 |
| SRM Auctions and Lettings Ltd | Real estate | 2018 |
| SSE Consultancy Ltd | Professional & scientific | 2021 |
| ST. Trea's AOH Community Hub Ltd | Education | 2024 |
| Staylit Services Ltd | Wholesale & retail | 2026 |
| Stevenson Trading Ltd | Hospitality | 2019 |
| Stone Solutions Stonemasons Ltd | Manufacturing | 2022 |
| Stonebright Energy Ltd | Energy | 2025 |
| Storm Motors (NI) Ltd | Wholesale & retail | 2016 |
| Stormtec Services Ltd | Manufacturing | 2018 |
| Strain Electrical Services Ltd | Manufacturing | 2015 |
| Strain Engineering and Co Limited | Manufacturing | 2012 |
| Strata 1 Limited | Information & communication | 2015 |
| Straw Farms Limited | Agriculture & fishing | 1997 |
| Streamline Joinery and Construction Limited | Construction | 2017 |
| Strike Holdings Ltd | Financial services | 2025 |
| Success Mindset Life Ltd | Professional & scientific | 2023 |
| Sunny's 2022 Ltd | Hospitality | 2022 |
| Superhero Fit Ltd | Education | 2023 |
| Supertec Ltd | Information & communication | 2026 |
| Surefac Ltd | Professional & scientific | 1999 |
| Sweeney-Macbride Ltd | Administrative & support | 2022 |
| Sweetwall Ltd | Real estate | 2020 |
| Swift Screw Products Limited | Wholesale & retail | 1975 |
| Sycamore Bay Company Limited | Extraterritorial | 2022 |
| Sycamore Heights Company Limited | Other services | 2016 |
| Sycamore Shelf Company Limited | Extraterritorial | 2017 |
| Sylium Ltd | Information & communication | 2024 |
| Syncseries Limited | Professional & scientific | 2013 |
| Szajkjyxgs Limited | Wholesale & retail | 2025 |
| T M Precast Concrete Ltd | Construction | 2014 |
| Tabbda Milk Bar Ltd | Hospitality | 2000 |
| Tailored Accident Management Ltd | Other services | 2021 |
| Tailored Financial Solutions Limited | Administrative & support | 2006 |
| Tailored Wealth Management Ltd | Financial services | 2019 |
| Tamlaght Equestrian Centre Ltd | Agriculture & fishing | 2021 |
| Tang's Kitchen Ltd | Hospitality | 2019 |
| Tard Services Ltd | Construction | 2025 |
| TAS Performance Bikes Ltd | Wholesale & retail | 2002 |
| TAS Salvage Management Ltd | Wholesale & retail | 2019 |
| Taurus Design & Engineering Ltd | Manufacturing | 2025 |