| School Garden Management Company Limited | Households | 2024 |
| Scientia Engineering Limited | Construction | 2018 |
| Scraghy Wind Ltd | Energy | 2014 |
| Secret Gallery Ltd | Arts & recreation | 2024 |
| Selena Nail and Spa Ltd | Other services | 2025 |
| Service Stream Ltd | Information & communication | 2023 |
| Serviced Stays Belfast Ltd | Hospitality | 2023 |
| Seventh Axis Ltd | Wholesale & retail | 2025 |
| Shanco Properties Limited | Construction | 1996 |
| Shane Mckernan Transport Ltd | Transport & logistics | 2026 |
| Shanmaghery Wind Ltd | Energy | 2012 |
| Sheila Nugent School of Reflexology & Holistic Therapies Limited | Health & social care | 2021 |
| Sholdy Laizhi Limited | Wholesale & retail | 2025 |
| Shollie Ltd | Wholesale & retail | 2024 |
| Shuaqiqi Limited | Wholesale & retail | 2024 |
| Sinley Chinese Limited | Hospitality | 2024 |
| Sitting SIP Limited | Hospitality | 2024 |
| Sixtyfourinvestments Ltd | Financial services | 2024 |
| SJC Properties (N.I.) Limited | Extraterritorial | 2011 |
| SKE Evolution Ltd | Manufacturing | 2019 |
| SL Excavators (NI) Ltd | Manufacturing | 2022 |
| Slots of FUN Ltd | Real estate | 2015 |
| SM Bedford Holdco 1 Limited | Financial services | 2016 |
| SM Bedford Limited | Financial services | 2016 |
| SM Blackrock Holdings Limited | Financial services | 2021 |
| SM Blackstaff Holdings Limited | Financial services | 2023 |
| SM Blackstaff Limited | Real estate | 2023 |
| SM Brighton Holdings Limited | Financial services | 2019 |
| SM Brighton Limited | Construction | 2019 |
| SM Dungannon Road Holdings Limited | Financial services | 2019 |
| SM Dungannon Road Limited | Real estate | 2019 |
| SM Ewart Holdings Limited | Financial services | 2022 |
| SM Great Victoria ST Limited | Real estate | 1990 |
| SM Guildford Holdings Limited | Financial services | 2019 |
| SM Guildford Limited | Construction | 2018 |
| SM James Street Holdings Limited | Financial services | 2019 |
| SM James Street Limited | Real estate | 2019 |
| SM Kildress Holdings Limited | Financial services | 2021 |
| SM Larkfield Holdings Limited | Financial services | 2021 |
| SM Malone 102 Limited | Real estate | 2011 |
| SM130 Limited | Extraterritorial | 2024 |
| Smackpol Ltd | Wholesale & retail | 2017 |
| Small World Childcare Limited | Health & social care | 2023 |
| Smallwood Certification Ltd | Construction | 2017 |
| SMC Developments Limited | Construction | 2023 |
| Solid Power Ltd | Construction | 2022 |
| Solo Direct Limited | Real estate | 2015 |
| Solo Power (NI) Ltd | Energy | 2013 |
| Solo Renewables (Dungiven) Ltd | Energy | 2013 |
| Solo Renewables Ltd | Energy | 2010 |
| Solo Retailing Ltd | Wholesale & retail | 2011 |
| Sota Piercing Ltd | Other services | 2023 |
| Sperrin Asset Company Limited | Professional & scientific | 2017 |
| Sperrin Logic Limited | Information & communication | 2023 |
| Sperrin Trading Services Limited | Manufacturing | 2016 |
| Springvale House Ltd | Energy | 2014 |
| SS. Gaming Ltd | Arts & recreation | 2003 |
| Stadia SSV Ltd | Administrative & support | 2024 |
| Steele Results Ltd | Administrative & support | 2026 |
| Steelweld Enviro Products Ltd | Extraterritorial | 2016 |
| Stewart Designs (NI) Limited | Professional & scientific | 2006 |
| Stonyford Furniture Limited | Manufacturing | 2005 |
| Stonyford Holdings Limited | Financial services | 2017 |
| Sunreagh Limited | Other services | 2012 |
| Swift Contract Consultants Ltd | Extraterritorial | 2020 |
| Sycamore Crescent Limited | Financial services | 2023 |
| Sycamore Grange Company Limited | Extraterritorial | 2021 |
| Sycamore Terrace Company Limited | Real estate | 2020 |
| Syntagma International Ltd | Professional & scientific | 2025 |
| Syntra Control Ltd | Professional & scientific | 2022 |
| T J Hamilton Developments 1 Ltd | Real estate | 2026 |
| T J Hamilton Developments Limited | Real estate | 1998 |
| T-B the Best Barber Shop Limited | Other services | 2024 |
| T.J.Hamilton & Company Limited | Wholesale & retail | 1983 |
| Tailleur Limited | Wholesale & retail | 2021 |
| Tannaghmore Properties Limited | Real estate | 2006 |
| Tatra LS Ltd | Professional & scientific | 2023 |
| Tattykeel Sales Ltd | Manufacturing | 2016 |
| TB Environmental Services Ltd | Professional & scientific | 2020 |
| TCT Developments Ltd | Construction | 2006 |
| TDA Consulting Limited | Information & communication | 2025 |
| TDL Groundworks Ltd | Construction | 2006 |
| Teague & Sally Ltd | Professional & scientific | 2005 |
| Termon Developments Limited | Real estate | 1995 |
| TES Power Ltd | Manufacturing | 2014 |
| TES Switchgear Ltd | Extraterritorial | 2014 |
| TGE Process Engineering Ltd | Professional & scientific | 2016 |
| THE Beeches (Cookstown) Management Company Limited | Households | 2018 |
| THE Fashion Boutique Limited | Wholesale & retail | 2021 |
| THE Lampshade Jungle Ltd | Manufacturing | 2021 |
| THE Laundry Box Ltd | Other services | 2026 |
| THE Mortgage Shop Cookstown Ltd | Financial services | 2026 |
| THE NI Utility Guys Ltd | Administrative & support | 2026 |
| THE Original Golden Bowl Ltd | Hospitality | 2024 |
| THE Pammer N.I. LLP | | 2011 |
| THE Posture Doctor Ltd | Health & social care | 2021 |
| THE Spruce Park Company Limited | Professional & scientific | 2016 |
| THE Strata Timber Group Ltd | Wholesale & retail | 2020 |
| THE Sycamore Avenue Company Limited | Financial services | 2017 |
| THE Tile Shed Ltd | Construction | 2019 |