| Sentinelgrid Consultancy Ltd | Information & communication | 2023 |
| Sentrylane Holdings Limited | Transport & logistics | 2021 |
| Sergio Hand Wash Ltd | Administrative & support | 2026 |
| Serpentine Road Limited | Real estate | 2016 |
| Serverless Edge Ltd | Information & communication | 2021 |
| Service Network (N.I.) LLP | | 2012 |
| Shackhub Initiatives Ltd | Information & communication | 2025 |
| Shahi Kebab and Tandoori Ltd | Hospitality | 2024 |
| Shambhavi House Ltd | Real estate | 2025 |
| Shand Media Design Limited | Professional & scientific | 2025 |
| Shankly Offshore Networks Limited | Construction | 2024 |
| Shannon Code Limited | Information & communication | 2015 |
| Shannons Estates Limited | Real estate | 2023 |
| Shared Medical Systems Limited | | 1992 |
| Shaw Tutors Ltd | Education | 2019 |
| SHC Services Ltd | Administrative & support | 2022 |
| SHE Shifts Automotive Limited | Wholesale & retail | 2026 |
| Sheaney Ltd | Construction | 2020 |
| Sheri's Kebab Express Ltd | Hospitality | 2022 |
| Sheridan Grass Solutions Limited | Administrative & support | 2016 |
| Sheridan Tree Services Limited | Agriculture & fishing | 2023 |
| SHG Power Networks Ltd | Professional & scientific | 2014 |
| SHH Retail Ltd | Hospitality | 2021 |
| Shires UK Limited | | 1990 |
| Shopland Woods Ltd | Wholesale & retail | 2025 |
| Shopvora Global Ltd | Wholesale & retail | 2026 |
| Shore Tyres & Autos Limited | Wholesale & retail | 2019 |
| Short Stay Belfast Ltd | Real estate | 2019 |
| Sign Language Cultural Centre (NI) Ltd | Education | 2025 |
| Signature Hair & Co Glengormley Ltd | Other services | 2023 |
| Singers Secreto Limited | Arts & recreation | 2019 |
| SIP & Savour Wines Ltd | Wholesale & retail | 2025 |
| Sips and Spirits Holding Ltd | Financial services | 2025 |
| Sips and Spirits Property Ltd | Real estate | 2025 |
| SIX Mile Bar & Restaurant Ltd | Hospitality | 2023 |
| Sjay Holdings Limited | Financial services | 2022 |
| SK Kebab Newtownabbey Limited | Hospitality | 2025 |
| Skellco Limited | Professional & scientific | 2025 |
| Slip Space Media Limited | Wholesale & retail | 2022 |
| Sllcm Property Ltd | Real estate | 2024 |
| SM Floors NI Ltd | Construction | 2026 |
| SMC Electrical Contractors Ltd | Construction | 2018 |
| SMK Creations Ltd | Information & communication | 2021 |
| Smurfit Westrock Consumer Belfast Limited | Manufacturing | 1960 |
| Social-Ability (EU) Limited | Health & social care | 2022 |
| Sodabread Theatre C.I.C. | Arts & recreation | 2020 |
| Soham Technologies Limited | Information & communication | 2023 |
| Solarfixni Ltd | Construction | 2015 |
| Solid Holdings Ltd | Administrative & support | 2016 |
| Solid Subs Boucher Ltd | Hospitality | 2025 |
| Solid Subs Ltd | Hospitality | 2017 |
| Source Airconditioning & Electricalservices (NI) Limited | Construction | 2009 |
| Southern Cross Property Investment Limited | Real estate | 2024 |
| SP NH Holdings Limited | Financial services | 2018 |
| SP Properties N.I. Ltd | Real estate | 2022 |
| Splash IT Ltd | Wholesale & retail | 2023 |
| Splash NI Car Care Ltd | Administrative & support | 2023 |
| Spring Upholstery Ltd | Manufacturing | 2020 |
| Square Comber Limited - the | Real estate | 2005 |
| Srmp Ltd | Transport & logistics | 2018 |
| SS Electrical Services N.I. Ltd | Construction | 2025 |
| SS Electrical Services. Ni.Ltd Ltd | Construction | 2026 |
| SS Grocery Ltd | Wholesale & retail | 2019 |
| ST Annes Grove Ltd | Households | 2013 |
| ST Property Maintenance Ltd | Construction | 2023 |
| Stand by Solutions Ltd | Information & communication | 2025 |
| Star Contract Hire Limited | Extraterritorial | 2011 |
| Star Rentals Limited | Administrative & support | 2011 |
| Steelworks Festival Ltd | Administrative & support | 2026 |
| Stephen Best Dental Care Limited | Health & social care | 2010 |
| Stevenson and Reid | Wholesale & retail | 1979 |
| Stop Car Garage Ltd | Other services | 2024 |
| Stop Car Transport Ltd | Transport & logistics | 2021 |
| Storage Belfast Ltd | Transport & logistics | 2018 |
| Storm Performance Ltd | Wholesale & retail | 2023 |
| Straidorn Properties Ltd | Real estate | 2016 |
| Stratton Home Improvements Ltd | Construction | 2026 |
| Streamvale Limited | Professional & scientific | 2006 |
| Streetmonkey Limited | Information & communication | 2002 |
| Studio Camino Design Ltd | Professional & scientific | 2026 |
| Studio.Nōur Ltd | Arts & recreation | 2025 |
| SUB Side Ltd | Hospitality | 2024 |
| Suitters Empire Ltd | Real estate | 2026 |
| Superior Health Ltd | Wholesale & retail | 2025 |
| Support to Perform Ltd | Professional & scientific | 2018 |
| Sure 4 Healthcare Ltd | Public administration | 2025 |
| Sure Deep Clean Ltd | Administrative & support | 2018 |
| Surf-Fur UK Ltd | Wholesale & retail | 2025 |
| Swan Song Serenity Ltd | Water & waste | 2024 |
| Swift Interiors Ltd | Construction | 2019 |
| Synchronised Cabling Solutions Limited | Construction | 2003 |
| Sypm Care Ltd | Health & social care | 2023 |
| System Automation Monitoring Limited | Professional & scientific | 2016 |
| T & S Wholesale Ltd | Wholesale & retail | 2023 |
| T&M Retail Ltd | Wholesale & retail | 2014 |
| T-Mac Golf Ltd | Arts & recreation | 2016 |
| T. M. R. Security Limited | Administrative & support | 2004 |
| Taber Groundworks Ltd | Construction | 2022 |
| Tagay Group Ltd | Hospitality | 2020 |
| Taka Sports Ltd. | Information & communication | 2019 |