| Styho Services Ltd | Professional & scientific | 2026 |
| Styling Sisters Ltd | Other services | 2020 |
| Subway Newry Limited | Hospitality | 2006 |
| Sugar House Quay Limited | Hospitality | 2026 |
| Sugar Island Developments Ltd | Financial services | 2021 |
| Summerdale Limited | Energy | 2015 |
| Summerhill Imports Ltd | Wholesale & retail | 2025 |
| Summit Capital (N.I.) Ltd | Real estate | 2024 |
| Sun Mobile & Web Developer Ltd | Wholesale & retail | 2024 |
| Sun Tech Solutions Ltd | Energy | 2025 |
| Sunbed Ireland Ltd | Other services | 2021 |
| Sunbeds Newry Limited | Other services | 2022 |
| Sunflower Belfast Limited | Real estate | 2014 |
| Sunny Dove Letting Company Limited | Real estate | 2026 |
| Sunray (Home Bakeries) Limited | Wholesale & retail | 1968 |
| Sunrise Fire Limited | Public administration | 2025 |
| Sunset Auctions International Ltd | Extraterritorial | 2022 |
| Sunshine 1049 Ltd | Wholesale & retail | 2017 |
| Sunshine Radio Ltd | Wholesale & retail | 2023 |
| Sunshine Tanning Limited | Other services | 2015 |
| Suntech Computer Services Ltd | Information & communication | 2014 |
| Supermac's (Northern Ireland) Limited | Hospitality | 2007 |
| Supreme Exterior Solutions Ltd | Construction | 2025 |
| Surefreight Limited | Transport & logistics | 1989 |
| Surewire Electrical Services Ltd | Construction | 2023 |
| Surg Power Limited | Professional & scientific | 2010 |
| Sustainable Aggregates Ltd | Water & waste | 2026 |
| Sustainable Design Group Ltd | Construction | 2025 |
| SUV Hire T/A 4X4 Vehicle Hire Limited | Administrative & support | 2018 |
| Suzie Transport Ltd | Transport & logistics | 2021 |
| SVM Prestige Ltd | Wholesale & retail | 2023 |
| SW Consultancy (N.I.) Ltd | Professional & scientific | 2017 |
| Swallow Groupage Services Limited | Transport & logistics | 2011 |
| Swan Rock Quarries Limited | Mining & quarrying | 2006 |
| Swede Beets Limited | Hospitality | 2019 |
| Sweet Briar (N.I.) Limited | Real estate | 2016 |
| Sweet Life Ireland Ltd | Hospitality | 2023 |
| Sweetexcare Ltd | Health & social care | 2024 |
| Swift Engineering (IRL) Ltd | Professional & scientific | 2009 |
| Swift Renewables Limited | Manufacturing | 2021 |
| Swiftful Ltd | Transport & logistics | 2022 |
| Swyft Sportswear Ltd | Wholesale & retail | 2026 |
| Synergy Facades Limited | Construction | 2019 |
| Syrian Bazaar Limited | Wholesale & retail | 2020 |
| T & a Electrical Limited | Administrative & support | 2010 |
| T & C Patterson Ltd | Mining & quarrying | 2007 |
| T - MAC Developments Limited | Construction | 2013 |
| T and J Furniture Limited | Manufacturing | 2019 |
| T Hughes Construction Limited | Construction | 2002 |
| T Law Group Limited | Financial services | 2025 |
| T Law Property Limited | Real estate | 2025 |
| T Morgan Motors Ltd | Wholesale & retail | 2021 |
| T N R Contracts Ltd | Construction | 2021 |
| T Rocks Transport Limited | Transport & logistics | 2011 |
| T Tots NI LLP | | 2025 |
| T Trainor Construction Ltd | Construction | 2018 |
| T&E Ailleacht Ltd | Other services | 2024 |
| T&L Resources UK Ltd | Financial services | 2023 |
| T. Conlon Commercial Repairs Ltd | Wholesale & retail | 2024 |
| T. Hanna Ltd | Manufacturing | 2003 |
| T. MAC Commercials Ltd | Wholesale & retail | 2018 |
| T.M.H. Distribution Ltd | | 2008 |
| Tailwind Developments Ltd | Construction | 2018 |
| TAJ Mahal Tandoori (N.I.) Limited | Hospitality | 2016 |
| Talamh Ventures Limited | Real estate | 2025 |
| Talent Tribe Consulting Ltd | Administrative & support | 2024 |
| Talingual Ltd | Administrative & support | 2016 |
| Talon Security Limited | Administrative & support | 2011 |
| Tamary Hill Solutions Limited | Wholesale & retail | 2024 |
| Tamary Tiling Ltd | Construction | 2025 |
| Tamary Tractors Ltd | Wholesale & retail | 2023 |
| Tammymore Developments Ltd | Construction | 2015 |
| Tango Group Europe Limited | Wholesale & retail | 2019 |
| Tank FAB Limited | Manufacturing | 2018 |
| Tannery Investments Ltd | Hospitality | 2017 |
| TAP 2 TIP Limited | Financial services | 2022 |
| Tapadoo Limited | Information & communication | 2009 |
| Tara Developments 2020 Ltd | Construction | 2020 |
| Tara Support Services Limited | Administrative & support | 2017 |
| Tara Walsh Solicitors Ltd | Professional & scientific | 2014 |
| Tarawood Apartments Management Company Limited | Households | 2005 |
| Tarawood Management Company Limited | Households | 2005 |
| Tarbh BAN Limited | Professional & scientific | 2025 |
| Target Umbrella Limited | Professional & scientific | 2009 |
| Tarjula Limited | Real estate | 1997 |
| Tarracor Robotics UK Ltd | Wholesale & retail | 2025 |
| Tarragon Bay Ltd | Manufacturing | 2021 |
| Taskc Limited | Wholesale & retail | 2012 |
| Taste of Gullion Limited | Wholesale & retail | 2021 |
| Tasty Newry Ltd | Hospitality | 2022 |
| Tate Hill Stables Ltd | Arts & recreation | 2021 |
| Tate Mechanical Ltd | Construction | 2026 |
| Taxi Day Tours Belfast Ltd | Transport & logistics | 2023 |
| Taxiline Newry Ltd | Transport & logistics | 2013 |
| Taylor Made NI Limited | Construction | 2004 |
| TB Merchants L.P. | | 2017 |
| TBH NI Operations Ltd | Wholesale & retail | 2021 |
| TBK Haulage Ltd | Transport & logistics | 2012 |
| TBR Homes Limited | Construction | 2017 |
| TCC Bricklaying Ltd | Construction | 2025 |