| SMC Utilities Ltd | Construction | 2018 |
| SMD Construction Limited | Construction | 2015 |
| SMD Insulation Limited | Construction | 2014 |
| SMG Civil Ltd | Construction | 2026 |
| SMK Fit OUT Ltd | Construction | 2016 |
| SML Motors Limited | Wholesale & retail | 2017 |
| SMX Developments Ltd | Real estate | 2007 |
| SMX Tyrone Limited | Real estate | 2011 |
| Soda Accessories T/A the Little Boutique Limited | Wholesale & retail | 2018 |
| Solasta Healthcare Limited | Health & social care | 2018 |
| Sonas Pharmaceuticals (N.I.) Limited | Professional & scientific | 2024 |
| Soupstone Films Ltd | Information & communication | 2020 |
| Source Gyms Ltd | Arts & recreation | 2017 |
| South West GP Federation C.I.C. | Health & social care | 2015 |
| SPD Civil Ltd | Construction | 2018 |
| Specialised Carrier Solutions Limited | Water & waste | 2012 |
| Speedify Ltd | Wholesale & retail | 2024 |
| Sperrin and Lakeland Skin Clinic Ltd | Health & social care | 2025 |
| Sperrin Equipment Limited | Financial services | 2014 |
| Sperrin Floor Screeds Ltd | Construction | 2025 |
| Sperrin Paints Ltd | Construction | 2021 |
| Sperrin Restaurant Omagh Ltd | Hospitality | 2019 |
| Sperrin Solar Systems Limited | Construction | 2013 |
| Sperrin Veterinary Limited | Professional & scientific | 2024 |
| Sperrin Wash & Go Ltd | Administrative & support | 2026 |
| Spherius Ltd | Professional & scientific | 2009 |
| Spre Properties Ltd | Real estate | 2019 |
| Spreagh Ltd | Construction | 2023 |
| Springlawn House Holdings Ltd | Financial services | 2023 |
| Springlawn House Ltd | Health & social care | 1989 |
| Sproule's Stores Ltd | Wholesale & retail | 2017 |
| Spruce Manor Limited | Real estate | 2016 |
| Sprucewood Ltd | Health & social care | 2020 |
| Square 4 Developments Limited | Real estate | 2024 |
| SRH Holding Co Ltd | Financial services | 2026 |
| ST Competitions Ltd | Wholesale & retail | 2026 |
| ST Patricks Close Management Company Limited | Households | 2024 |
| ST. Conor's Play Zone C.I.C. | Health & social care | 2016 |
| Stafford Electrical Contracts Ltd | Construction | 2017 |
| Star Equipment Limited | Agriculture & fishing | 2020 |
| Starling Aircraft Seating Limited | Manufacturing | 2016 |
| Stephen Allen Motors Ltd | Wholesale & retail | 2018 |
| Stephen Coulter Ltd | Financial services | 2013 |
| Stephen Hunter Lawnmowers Ltd | Manufacturing | 2013 |
| Stephen Thompson Motors Ltd | Wholesale & retail | 2017 |
| Stitch and Ember Ltd | Wholesale & retail | 2025 |
| STM (N.I.) Ltd | Construction | 2016 |
| Storas Automotive Ltd | Wholesale & retail | 2026 |
| Straid Consulting | Professional & scientific | 2017 |
| Strategic BID Services Ltd | Professional & scientific | 2020 |
| Strathroy Dairies Limited | Wholesale & retail | 2012 |
| Strathroy Dairy Limited | Manufacturing | 1986 |
| Strathroy Rental Services Ltd | Real estate | 2026 |
| Stratos Corporate Development Ltd. | Professional & scientific | 2016 |
| Strawteck Ltd | Manufacturing | 2017 |
| Strong Foundations Coaching Ltd | Arts & recreation | 2025 |
| Strucsure Property Services Ltd | Construction | 2025 |
| Structyour Ltd | Information & communication | 2025 |
| Strule Coffee Shop Limited | Hospitality | 2019 |
| Strule Holdings Ltd | Financial services | 2023 |
| Strule Rentals Ltd | Construction | 2010 |
| Strule Tributaries and Rivers Trust Limited | Agriculture & fishing | 2014 |
| Stud Weld Ireland Ltd | Professional & scientific | 2019 |
| Studio Bandia Ltd | Wholesale & retail | 2023 |
| Style Boutique (Omagh) Ltd | Wholesale & retail | 2015 |
| Style Boutique Enniskillen Ltd | Wholesale & retail | 2020 |
| Sunflowers Help Limited | Arts & recreation | 2023 |
| Super Fresh Food Limited | Wholesale & retail | 2006 |
| Supremus Ltd | Professional & scientific | 2014 |
| Sureview Trading Ltd | Wholesale & retail | 2025 |
| Surface Form Ltd | Extraterritorial | 2009 |
| SW Civils Limited | Construction | 2025 |
| SW Textiles Ltd | Households | 2011 |
| Swann Contracts Ltd | Construction | 2014 |
| Sweenbrook Property Ltd | Real estate | 2018 |
| Swift Retail Limited | Wholesale & retail | 2008 |
| Synchron Limited | Information & communication | 2002 |
| T & a Concrete Pumping Hire Ltd | Construction | 2015 |
| T & J Recycling Ltd | Manufacturing | 2012 |
| T Tools Wholesale Limited | Wholesale & retail | 2019 |
| T'S Takeaway Gortin Ltd | Hospitality | 2024 |
| T. Brogan & SON (Farms) Ltd | Agriculture & fishing | 2021 |
| T. Brogan & SON Ltd | Mining & quarrying | 2019 |
| T. D. Pubs Ltd | Hospitality | 2016 |
| T.C. Autos Ltd | Wholesale & retail | 1988 |
| T2 Enniskillen Limited | Hospitality | 2015 |
| T2 Home Bakery Ltd | Hospitality | 2025 |
| T2 Lisburn Ltd | Hospitality | 2017 |
| T2 Omagh Ltd | Hospitality | 2015 |
| Tabragh Ltd | Real estate | 2014 |
| Taggart Transport Ltd | Transport & logistics | 2022 |
| Taggart's Stores Ltd | Wholesale & retail | 2025 |
| Taleshack Productions Ltd | Information & communication | 2025 |
| Talkshalk Ltd | Other services | 2021 |
| Tamlaght Mews (Block a ) Limited | Households | 2008 |
| Tamlaght Mews (Block B) Limited | Households | 2008 |
| Tamlaght Mews Maintenance Company Limited | Administrative & support | 2017 |
| Tamlaught Farms Ltd | Agriculture & fishing | 2026 |
| Tastisan Ltd | Hospitality | 2021 |
| Tasty Mac’S Takeaway Limited | Hospitality | 2025 |