| SB Welding & Mechanical Limited | Professional & scientific | 2024 |
| SBB (N.I.) Ltd | Wholesale & retail | 2024 |
| SC Service Centre Ltd | Wholesale & retail | 2015 |
| SCO Agri Mechanical Engineering and Coatings Ltd | Wholesale & retail | 2022 |
| Scott Enterprises (N.I.) Ltd | Administrative & support | 2017 |
| SCU (N.I.) Ltd | Other services | 2020 |
| Sdsa Holdings Ltd | Construction | 2025 |
| Sea View B&B (Larne) Ltd | Hospitality | 2017 |
| Secure App Design Limited | Information & communication | 2025 |
| Securityni Ltd | Professional & scientific | 2018 |
| Select Energy Engineering Limited | Manufacturing | 2003 |
| Selfie Care Ltd | Wholesale & retail | 2019 |
| Sentinel Health Ltd | Health & social care | 2016 |
| Setstainability Ltd | Arts & recreation | 2024 |
| Sfja Ltd | Professional & scientific | 2021 |
| Shamrock Apartments Management Company Limited | Real estate | 2015 |
| Sharon Woodside Motors Ltd | Wholesale & retail | 2012 |
| Shek Beauty Ltd | Other services | 2024 |
| Shek Hair Limited | Professional & scientific | 2011 |
| Sheq Support Ltd | Professional & scientific | 2021 |
| Sherkin Enterprises Limited | Construction | 2015 |
| Shift Performance (Global) Ltd | Arts & recreation | 2024 |
| Shimna Properties Limited | Real estate | 1996 |
| Shore Coast Developments Ltd | Construction | 2023 |
| Simco Business Ltd | Administrative & support | 2026 |
| Simco Property Management NI Limited | Households | 2021 |
| SJM Property Developers Ltd | Construction | 2013 |
| SJP Services Larne Ltd | Professional & scientific | 2015 |
| Skellig Enterprises Ltd | Construction | 2022 |
| Sleepy Hollow NI Limited | Hospitality | 2022 |
| SLT Events Ltd | Arts & recreation | 2023 |
| Sluggan BOG Solar Limited | Water & waste | 2023 |
| SM (N.I.) Limited | Wholesale & retail | 2019 |
| SM94 Ltd | Hospitality | 2025 |
| Smart Care Alliance Ltd | Health & social care | 2024 |
| Smart Energy Solutions NI Ltd Ltd | Manufacturing | 2014 |
| Smcintyretrading Ltd | Wholesale & retail | 2026 |
| Softwash Evolution Ltd | Administrative & support | 2024 |
| Solar (N.I.) Ltd | Construction | 2025 |
| Solarflexx (NI) Ltd | Construction | 2026 |
| Source Inspection Ltd | Manufacturing | 2023 |
| South Roots Ni&Ie Ltd | Wholesale & retail | 2026 |
| Spear & Arrow Bone Broth Ltd | Manufacturing | 2020 |
| Spelve Enterprises Limited | Manufacturing | 2018 |
| SPM (N.I.) Ltd | Hospitality | 2026 |
| SRB Crawford Ltd | Professional & scientific | 2015 |
| Sroseglobal Ltd | Manufacturing | 2021 |
| SS45 Ltd | Professional & scientific | 2024 |
| SSC (N.I.) Ltd | Wholesale & retail | 2020 |
| Ssppm Ltd | Professional & scientific | 2020 |
| ST Events and Entertainment Ltd | Arts & recreation | 2016 |
| ST Ives Property NI Limited | Real estate | 2026 |
| Stanaslaus Investments Limited | Real estate | 2020 |
| Standing Stone Investments Limited | Financial services | 2024 |
| Stay Aims Limited | Wholesale & retail | 2026 |
| Stealth Translations Limited | Professional & scientific | 2010 |
| Stephen Brain PLA Ltd | Professional & scientific | 2024 |
| Stephen Church Ltd | Transport & logistics | 2025 |
| Stephen Wylie Ltd | Construction | 2006 |
| Stockton Haulage Limited | Transport & logistics | 2024 |
| Stylux Development Company Limited | Real estate | 1999 |
| Summit Horizon Investments Ltd | Financial services | 2025 |
| Superior NI Group Holdings Ltd | Administrative & support | 2019 |
| Superior Renewables Limited | Wholesale & retail | 2024 |
| Supporting Sport Services (NI) Limited | Arts & recreation | 2012 |
| Supreme (N.I.) Ltd | Construction | 2021 |
| Sustainable People Performance Limited | Professional & scientific | 2017 |
| Sustainable Trench Technologies Ltd | Construction | 2021 |
| Swift Spectrum Limited | Wholesale & retail | 2024 |
| Swingnbling Outdoors Sports & Leisure Limited | Wholesale & retail | 2024 |
| Synergy Engineering + Environment Ltd | Administrative & support | 2015 |
| T D Meats Limited | Manufacturing | 2019 |
| T Mckeen Limited | Extraterritorial | 2012 |
| T&T Ventures Ltd | Education | 2026 |
| T. F. Woodside & Co. Limited | Real estate | 1972 |
| Table of the SOL Limited | Manufacturing | 2017 |
| Task Ireland Limited | Administrative & support | 2017 |
| Taylormade World Travel Ltd | Administrative & support | 2015 |
| TC Distributors Ltd | Wholesale & retail | 2015 |
| Tdts (N.I.) Ltd | Hospitality | 2020 |
| Telecom Design Solutions Ltd | Information & communication | 2022 |
| Terumo BCT Ltd. | Manufacturing | 2004 |
| Teutoniq Ltd | Professional & scientific | 2015 |
| Teva Milbrook Holdings Limited | Professional & scientific | 1991 |
| Teva NI Limited | Manufacturing | 1989 |
| THE (NI) Country Gardener Ltd. | Administrative & support | 2016 |
| THE Academy LLB Limited | Education | 2018 |
| THE Breakfast Bar Larne Ltd | Hospitality | 2019 |
| THE Car Wash Company (N.I.) Ltd | Other services | 2015 |
| THE Coffee Oche Ltd | Hospitality | 2026 |
| THE Cosy Corner Ltd | Hospitality | 2014 |
| THE CUE Gallery Ltd | Wholesale & retail | 2022 |
| THE Finishing Touch Roofing and Painting Ltd | Construction | 2025 |
| THE Flower Shed Ltd | Agriculture & fishing | 2025 |
| THE GAS MAN (N.I.) Ltd | Construction | 2019 |
| THE GAS MAN (N.I.) Services Ltd | Manufacturing | 2019 |
| THE Gear Shift Crew Limited | Professional & scientific | 2025 |
| THE GEM House (Ukni) Ltd | Wholesale & retail | 2023 |
| THE Global Financial Organisation Ltd | Professional & scientific | 2011 |
| THE Health Collective Ltd | Arts & recreation | 2022 |