| Titans Cheer NI CIC | Arts & recreation | 2023 |
| TJ Mcconnell and Sons Ltd | Manufacturing | 2013 |
| TJF Contracts Ltd | Construction | 2024 |
| Tjimrade HEQ Limited | Wholesale & retail | 2025 |
| TK Brolly Enterprises (2020) Ltd | Other services | 2020 |
| TKC Quality Solutions Limited | Construction | 2025 |
| TL Contracts NI Limited | Construction | 2021 |
| TL Entertainment Ltd | Arts & recreation | 2023 |
| TM & LM Ltd | Wholesale & retail | 2018 |
| TM Security (IRE) Limited | Administrative & support | 2024 |
| TM20 Ltd | Construction | 2016 |
| Tmcl & Sons Contracts Ltd | Construction | 2014 |
| Tmcl Plant Hire Limited | Administrative & support | 2016 |
| TML Engineering Ltd | Professional & scientific | 2016 |
| Toast Accountants Ltd | Professional & scientific | 2021 |
| Todds Developments Limited | Real estate | 2002 |
| Toland Training Limited | Public administration | 2022 |
| TOM and Betty Properties Limited | Real estate | 2015 |
| Tony Graham Plastering (NI) Limited | Construction | 2019 |
| Tooban S Boys Ltd | Real estate | 2014 |
| Top Line Tiles NI Limited | Wholesale & retail | 2024 |
| Top Quality Interiors Ltd | Wholesale & retail | 2021 |
| Top Tier Invest Ltd | Real estate | 2024 |
| Top-Line Contracts Ltd | Construction | 2021 |
| TOR Tiger Ltd | Information & communication | 2023 |
| Tora-Gwen Productions Ltd | Information & communication | 2026 |
| Torneys' (Omagh) Limited | Real estate | 1970 |
| Total Asset Security Limited | Administrative & support | 2011 |
| Total Entertainments DT Limited | Arts & recreation | 2022 |
| Total Golf Ltd | Wholesale & retail | 2015 |
| Total Site Worx Ltd | Construction | 2015 |
| TP Mccloskey Limited | Construction | 2007 |
| TP1 Properties Ltd | Financial services | 2021 |
| TPB1 Retail Ltd | Hospitality | 2025 |
| TPD (Derry) Limited | Wholesale & retail | 2017 |
| TPD Investments Ltd | Real estate | 2022 |
| Tpm(Ni) Limited | Construction | 2026 |
| TPS Drains Ltd | Administrative & support | 2022 |
| TR (North West) Ltd | Hospitality | 2018 |
| TRA Getaways Ltd | Hospitality | 2025 |
| Tractor Kings UK Limited | Wholesale & retail | 2025 |
| Trade Canvas Co Ltd | Manufacturing | 2020 |
| Tradeflowai Ltd | Professional & scientific | 2025 |
| Tradesource LS Ltd | Professional & scientific | 2022 |
| Traj Fusion Limited | Professional & scientific | 2021 |
| Travel EZ Ltd | Wholesale & retail | 2024 |
| Trillectra AI Ltd | Information & communication | 2025 |
| Trinity Estate Agents Limited | Real estate | 2006 |
| Triple Bridge Consultancy Limited | Hospitality | 2025 |
| Triquetra Security Services Ltd | Administrative & support | 2023 |
| Triskele Holistic Academy Ltd | Education | 2026 |
| Troublemakers Supply Co Ltd | Wholesale & retail | 2025 |
| Truepay Partners Limited | Wholesale & retail | 2026 |
| TSD Derry Limited | Hospitality | 2026 |
| TTR Leisure Ltd | Other services | 2016 |
| TU8ARA Limited | Information & communication | 2019 |
| Tudor Digital Ltd | Information & communication | 2024 |
| TUK Contracts Limited | Construction | 2020 |
| Tullanee Farm Ltd | Agriculture & fishing | 2014 |
| Turbo Sparks Ltd | Wholesale & retail | 2015 |
| Turkish Barber 47 Ltd | Other services | 2026 |
| TVL Properties Ltd | Real estate | 2017 |
| Twano Limited | Construction | 2009 |
| Twisted Services Ltd | Construction | 2021 |
| Type 1 Hype Ltd | Manufacturing | 2019 |
| TYPE40 Ltd | Information & communication | 2014 |
| Tyre Service Centre Limited | Wholesale & retail | 2023 |
| TÉD Investment Ltd | Real estate | 2025 |
| U-Boat Distillery Ltd | Manufacturing | 2025 |
| Uimhir a 4 Ltd | Information & communication | 2025 |
| UK Cultural Education Exchange Consulting Limited | Education | 2024 |
| Ulster FRY Limited | Wholesale & retail | 2015 |
| Ulster Roofing & Guttering Ltd | Construction | 2025 |
| Ulster Systems Limited | Real estate | 1971 |
| Ultimate Dresses Limited | Wholesale & retail | 2015 |
| Ultimate Menswear Limited | Wholesale & retail | 2016 |
| Ultrasound Scan Clinic Ltd | Health & social care | 2023 |
| Unique Timber Frame Solutions Limited | Manufacturing | 2014 |
| Unit 7AUDIO Visual Ltd | Administrative & support | 2011 |
| Unity Solutions Corporation Ltd | Wholesale & retail | 2023 |
| Universal Cleaning Supplies Limited | Real estate | 1987 |
| Urban Hospitality (N.I.) Ltd | Real estate | 2020 |
| Urban Lifters Ltd | Wholesale & retail | 2015 |
| Urban Trading (Derry) Ltd | Wholesale & retail | 2013 |
| Utopia Health & Leisure Ltd | Health & social care | 2023 |
| UV Arts C.I.C. | Arts & recreation | 2015 |
| Vale Automotive Ireland Limited | Manufacturing | 2022 |
| Vale Partitions Ltd | Construction | 2019 |
| Valetta Developments Limited | Professional & scientific | 2008 |
| Vandanath Ltd | Health & social care | 2022 |
| Vans Direct for YOU Limited | Wholesale & retail | 2018 |
| Variety Entertainment Limited | Extraterritorial | 2021 |
| Vckihs Jourp Ltd | Wholesale & retail | 2024 |
| Vdev Limited | Information & communication | 2018 |
| VDS Metalworks Ltd | Manufacturing | 2019 |
| Velocity Car Sales Ltd | Wholesale & retail | 2023 |
| Velvet and Lace NI Ltd | Arts & recreation | 2025 |
| Venturo Enterprises Ltd | Real estate | 2026 |
| Veritas Company Limited | | 2002 |
| Veritas Tours Ltd | Administrative & support | 2025 |