| Strabane Limited | Extraterritorial | 2024 |
| Straco Limited | Extraterritorial | 2024 |
| Stronger Psychological Services Ltd | Health & social care | 2023 |
| Suno Solar Installs Ltd | Construction | 2024 |
| Sunvault Distribution Limited | Financial services | 2025 |
| Superior Suites Limited | Real estate | 2024 |
| Supporting Communities NI | Other services | 1992 |
| Surface Design LAB Ltd | Construction | 2025 |
| Surreal Design Ltd | Wholesale & retail | 2017 |
| Swift Shift Removals Ltd | Transport & logistics | 2008 |
| Swimstarsni Limited | Education | 2022 |
| System Controls Limited | Manufacturing | 2004 |
| T Devlin Limited | Wholesale & retail | 2003 |
| TA Downey (Builders) Ltd | Construction | 2023 |
| Tails of Antrim Ltd | Other services | 2026 |
| Takafaith Health Care Ltd | Health & social care | 2022 |
| Tamnamore Lcis Ltd | Energy | 2023 |
| Tandragee Lcis Ltd | Energy | 2023 |
| Tapaidh Consulting Ltd | Professional & scientific | 2025 |
| Target Transport Limited | Transport & logistics | 1996 |
| Taylor & Toal Ltd | Health & social care | 2013 |
| Taylorstown Cross Community Complex Ltd | Education | 1999 |
| Team Air Power Holdings Ltd | Manufacturing | 2020 |
| Team Air Power Ltd | Manufacturing | 2020 |
| Tech Train X-R Ltd | Education | 2025 |
| Techmet Appointments Ltd | Administrative & support | 2011 |
| Technical Brands UK & Ireland Ltd | Wholesale & retail | 2018 |
| TED & Stitch Limited | Manufacturing | 2020 |
| Tedberry Limited | Wholesale & retail | 2022 |
| Teqball NI Limited | Administrative & support | 2021 |
| Terrick Limited | Transport & logistics | 2004 |
| Terrygowan Farm Limited | Agriculture & fishing | 2025 |
| Texture Craft Wall Systems Ltd | Construction | 2021 |
| Thankworthy Limited | Health & social care | 2024 |
| THE Arcade Chip Shop Ltd | Hospitality | 2010 |
| THE Bearded Handymen Ltd | Construction | 2020 |
| THE Bereans Publishing Ltd | Manufacturing | 2017 |
| THE Dandelion Cafe and Bakery Ltd | Manufacturing | 2026 |
| THE ELK Toome Limited | Hospitality | 2025 |
| THE Engine Room S&C Ltd | Arts & recreation | 2025 |
| THE Essence Vault Ltd | Wholesale & retail | 2019 |
| THE Film Club Studios Limited | Information & communication | 2020 |
| THE Foot DOC N.Ireland Limited | Health & social care | 2026 |
| THE Gaitway Organisation | Health & social care | 2019 |
| THE Globe Afterschool Ltd | Health & social care | 2025 |
| THE Kebab at Door Limited | Hospitality | 2023 |
| THE Lettings Company (NI) Limited | Real estate | 2011 |
| THE Mango Girl CIC | Health & social care | 2019 |
| THE Murtree Empire Ltd | Administrative & support | 2020 |
| THE Old Forge Ltd | Hospitality | 2014 |
| THE POP in Community Cafe CIC | Hospitality | 2025 |
| THE Treehouse (N.I.) Limited | Other services | 2018 |
| THE Turbo Shack Ltd | Wholesale & retail | 2016 |
| THE U Bolt Shop Ltd | Manufacturing | 2021 |
| THE Vintage Wine Merchants Ltd | Wholesale & retail | 2017 |
| Third Day Coffee Ltd | Hospitality | 2018 |
| Thomson Carter Limited | Wholesale & retail | 2023 |
| Thornton Holdings Limited | Real estate | 2016 |
| Thornton Roofing (Ireland) Limited | Construction | 2001 |
| Thousand Stiches Limited | Wholesale & retail | 2015 |
| Thousand Stitches by RR Ltd | Manufacturing | 2026 |
| Thrv.Lifestyle Ltd | Arts & recreation | 2024 |
| Time Investments (N.I) Ltd | Real estate | 2015 |
| Tiny House Coffee Ltd | Hospitality | 2022 |
| Titanic UK Holdings Limited | Financial services | 2026 |
| Tiyga (NI) Ltd | Information & communication | 2013 |
| TMH 47 Ltd | Other services | 2022 |
| Tnca Ltd | Professional & scientific | 2017 |
| TND Management Services Limited | Real estate | 2017 |
| Tolcy Ltd | Wholesale & retail | 2026 |
| Tolcy Property Ltd | Real estate | 2026 |
| Tomguard Ltd | Information & communication | 2026 |
| Tonusree Traders Ltd | Wholesale & retail | 2023 |
| Toome Dental Limited | Health & social care | 2015 |
| Toome EEL Fishery (Northern Ireland),Limited | Agriculture & fishing | 1959 |
| Top Nails & Spa Antrim Ltd | Other services | 2024 |
| Topglass Contracts Holdings Ltd | Financial services | 2013 |
| Towers Cleaning & Labour Services Limited | Households | 2011 |
| Townparks Service Station Ltd | Wholesale & retail | 2018 |
| Traction Engine Club of Ulster Limited | Other services | 1989 |
| Traction Promotions Ltd | Extraterritorial | 2026 |
| Training for Mental Health (NI) Limited | Education | 2022 |
| Training Solutions (NI) Ltd | Education | 2004 |
| Trans-Bridge Freight Services (NI) Ltd | Extraterritorial | 2025 |
| TRANS4M Physique Coaching Ltd | Arts & recreation | 2025 |
| Transparency Communications Limited | Professional & scientific | 2006 |
| Trend Fitout Ltd | Construction | 2011 |
| Tristan Kinnear Limited | Agriculture & fishing | 2011 |
| Troy Trajano Consultancy Ltd | Information & communication | 2024 |
| Truffles Bakery Ltd | Wholesale & retail | 2018 |
| Truffles Tearooms Ltd | Hospitality | 2018 |
| Ttic Tradings and Projects Ltd | Wholesale & retail | 2021 |
| Tullymally Management Services Limited | Transport & logistics | 2024 |
| Tumi 2024 Ltd | Real estate | 2024 |
| Twinrock Limited | Manufacturing | 2002 |
| Ubercan Ltd | Wholesale & retail | 2021 |
| UK (Ireland) Equipment Limited | Wholesale & retail | 2018 |
| UK Awarding and Assessment Board Ltd | Education | 2016 |
| UK Olight Limited | Wholesale & retail | 2018 |
| Ulster Deliveries Limited | Professional & scientific | 1977 |