| Sentry Properties Limited | Construction | 2001 |
| Seven Springs Management Limited | Extraterritorial | 2009 |
| SG INT Ltd | Professional & scientific | 2022 |
| Shaftesbury Estate of Lough Neagh Limited-The | Agriculture & fishing | 1964 |
| Sharonmore Management Company Limited | Households | 2017 |
| Sharp Pencil Consultancy Limited-The | Professional & scientific | 1997 |
| Sheeo Consultancy Limited | Professional & scientific | 2026 |
| Shining Lights | Arts & recreation | 2017 |
| Signal and Systems Engineering Ltd | Professional & scientific | 2026 |
| Sima's Flavor Ltd | Hospitality | 2025 |
| Simon Mcbride Publishing & Touring Ltd | Information & communication | 2018 |
| SIX Mile Fuels Ltd | Wholesale & retail | 2019 |
| SIX Mile View Ltd | Professional & scientific | 2024 |
| Sixmile Manor Land Management Ltd | Extraterritorial | 2004 |
| Sixmile Mews Ballyclare Management Ltd | Households | 2020 |
| Skeboy Land Management Ltd | Extraterritorial | 2003 |
| Skinner Sales Synergy Limited | Professional & scientific | 2025 |
| Slieve DHU Limited | Health & social care | 2001 |
| SLK West Consulting Ltd | Professional & scientific | 2024 |
| Smart Marketing Group Ltd | Professional & scientific | 2019 |
| Smart Practices Ltd | Health & social care | 2016 |
| Smart Simple Logistics Ltd | Transport & logistics | 2021 |
| Smartevtesting.Com Limited | Wholesale & retail | 2025 |
| Smartvideo Ltd | Manufacturing | 2014 |
| Soccer Shed Ballyclare Ltd | Arts & recreation | 2023 |
| Software and AI Services Ltd | Information & communication | 2025 |
| SOK Vision Ltd | Wholesale & retail | 2021 |
| Solburn Energy Ltd | Construction | 2015 |
| Solid Rock Developments Limited | Construction | 2022 |
| Somerton Mews Property Management Limited | Households | 1998 |
| Soul Feet Ltd | Hospitality | 2003 |
| Source Essentials Ltd | Wholesale & retail | 2024 |
| Spark Engineering Limited | Professional & scientific | 2022 |
| Specialist Deli Group Ltd | Wholesale & retail | 2016 |
| Specialist Vehicles Group Ltd | Wholesale & retail | 2016 |
| Sphinx Belfast Limited | Hospitality | 2025 |
| Sphinx EG Ltd | Extraterritorial | 2024 |
| Sphinx Hot Food Ltd | Hospitality | 2008 |
| Sphinx Kebabs Ltd | Hospitality | 2008 |
| Spoc Homes Limited | Construction | 2018 |
| Spooktacular Limited | Extraterritorial | 2015 |
| Spring Cottages Management Company Limited | Households | 2017 |
| Springfarm Court Management Ltd | Extraterritorial | 2005 |
| Springfields (Kells) Management Ltd | Households | 2018 |
| Springhill Meadows Management Limited | Households | 2009 |
| SQ CUT Limited | Hospitality | 2026 |
| SSI Farms Limited | Agriculture & fishing | 2019 |
| ST Catherine's Court Armagh Management Company Limited | Extraterritorial | 2004 |
| ST. Anne's Court Apartments Ltd | Extraterritorial | 2012 |
| ST. Mary's Gardens Management Company Limited | Households | 2003 |
| Star & Gate Ltd | Information & communication | 2020 |
| Star Car Hire Limited | Transport & logistics | 2005 |
| Star Car Show Ltd | Arts & recreation | 2026 |
| Station Manor Management Limited | Households | 2017 |
| Steel MAC Distribution (SMD) Ltd | Manufacturing | 2014 |
| Steeles Fuel Freight Limited | Transport & logistics | 2011 |
| Steenson Holdings Limited | Wholesale & retail | 2020 |
| Stem & Scent Ltd | Wholesale & retail | 2020 |
| Steven Elliott Construction Ltd | Construction | 2022 |
| Stewarts Cash Stores Limited | Wholesale & retail | 2019 |
| STM Property Limited | Real estate | 2014 |
| Stone Stead Ltd | Real estate | 2025 |
| Stonebridge Land Management Ltd | Households | 2025 |
| Straidnahanna Racing Limited | Arts & recreation | 2016 |
| Strand Recycling Ltd | Water & waste | 2026 |
| Stranmillis Chippy Limited | Hospitality | 2022 |
| Strawhill Demesne Management Ltd | Extraterritorial | 2005 |
| Stream Dynamics Limited | Manufacturing | 2014 |
| Stronger Property Ltd | Real estate | 2026 |
| Stuart Consultancy Group Ltd | Professional & scientific | 2024 |
| Studio Tone & TAN (NI) Limited | Other services | 2013 |
| Sunlea Court Property Management Ltd | Extraterritorial | 2002 |
| Support Care Recruitment Ltd | Administrative & support | 2013 |
| Surien Ltd | Professional & scientific | 2025 |
| Svanna Ltd | Water & waste | 2022 |
| Synergy Construction Services (NI) LLP | | 2009 |
| TAM Agri Ltd | Wholesale & retail | 2026 |
| Tamnamore Management Company Limited | Extraterritorial | 2006 |
| Tanya Ross Coaching Ltd | Health & social care | 2025 |
| Tartan Paint Antrim | Extraterritorial | 1974 |
| Tasty Grub Club Limited | Hospitality | 2020 |
| Taughey Road Land Management Ltd | Households | 2022 |
| Taughrane Lodge Limited | Households | 2006 |
| Tauraro Ltd | Information & communication | 2023 |
| Taylor Fuels Limited | Wholesale & retail | 2019 |
| Taylorstown Road Property Management Ltd | Extraterritorial | 2007 |
| Tbcni Ltd | Arts & recreation | 2021 |
| Tea GC Ltd | Hospitality | 2024 |
| Technically Write Ltd | Information & communication | 2024 |
| Technology Centre Belfast Ltd | Wholesale & retail | 2025 |
| Tekton Services Ltd | Construction | 2024 |
| Telfair Tailoring Ltd | Wholesale & retail | 2020 |
| Temple Hall Land Management Ltd | Extraterritorial | 2015 |
| Temple Road Management Company Ltd | Households | 2005 |
| Templepatrick Paediatric Clinic Limited | Health & social care | 2018 |
| TEN Minutes More Limited | Administrative & support | 2015 |
| Termapest Fumigation Limited | Administrative & support | 2019 |
| Termapest Ltd | Administrative & support | 2001 |
| Terry Coulter Cars Ltd | Wholesale & retail | 2016 |
| Thalassa House Management Company Limited | Households | 2016 |