| Southside Social Accommodation Ltd | Hospitality | 2026 |
| Space Belfast Ltd | Arts & recreation | 2025 |
| Sparkle Like YOU Mean IT Limited | Information & communication | 2025 |
| Speers (Contractors) Limited | Real estate | 1961 |
| SPM Dawson Whyte (Life & Pensions) Limited | Financial services | 1986 |
| Sporting Trials Car Club Limited | Arts & recreation | 1979 |
| SPS Performance Coaching Ltd | Education | 2026 |
| Sreg Limited | Construction | 2016 |
| Srotas Health Ltd | Information & communication | 2022 |
| ST. Helen's Court Apartments Limited | Households | 1988 |
| ST. Helen's House Holywood Apartments Limited | Households | 1994 |
| ST. John's Wharf Management Company Limited | Households | 2004 |
| Stephen Clarke Consulting Limited | Professional & scientific | 2003 |
| Steps 55 Ltd | Hospitality | 2019 |
| Steps Ahead (N.I.) Ltd | Hospitality | 2020 |
| Stmdee Ltd | Wholesale & retail | 2024 |
| Stockmarket Teachers Ltd | Education | 2012 |
| Stonegate Homes (Chalfont Park) Limited | Construction | 2018 |
| Stonegate Homes (Cricklewood) Limited | Construction | 2018 |
| Stonegate Homes (Croydon) Limited | Construction | 2018 |
| Stonegate Homes (Enfield) Limited | Construction | 2018 |
| Stonegate Land & Property Limited | Administrative & support | 2017 |
| Stonegate Land and Estates Limited | Construction | 2017 |
| Storm Spinning Limited | Arts & recreation | 2018 |
| Stornoway Hill Ltd | Arts & recreation | 2023 |
| Stranmillis Wharf Management Company Limited | Households | 2001 |
| Strategic Planning Consulting Holdings Limited | Financial services | 2018 |
| Strategic Planning Consulting Limited | Professional & scientific | 2006 |
| Studio A35 Ltd | Arts & recreation | 2023 |
| Studio Momentos Ltd | Information & communication | 2022 |
| Studio Prop Makers Ltd | Information & communication | 2010 |
| Suitor Devlin Limited | Hospitality | 2021 |
| Sundowner Properties Ltd | Real estate | 2021 |
| SWH Fitting Services Ltd | Construction | 2009 |
| Swng Limited | Arts & recreation | 2026 |
| Synq-X Ltd | Information & communication | 2026 |
| T.D. Lorimer & Company Limited | Financial services | 1965 |
| Tailor Made Training Ireland Limited | Other services | 2002 |
| Tandem Partners Ltd | Professional & scientific | 2012 |
| Tapp Directory Ltd | Information & communication | 2024 |
| Tapp Industries Ltd | Manufacturing | 2025 |
| Tea With ME Ltd | Manufacturing | 2022 |
| Tealstone Developments Limited | Construction | 1986 |
| Templeton Robinson Commercial Ltd | Real estate | 2022 |
| Terrier Partners Limited | Financial services | 2019 |
| Tharma Ventures Limited | Administrative & support | 2025 |
| THE 3-20 Way Ltd | Other services | 2025 |
| THE Coop Troop Holdings Limited | Information & communication | 2020 |
| THE Coop Troop Productions Limited | Information & communication | 2020 |
| THE Coop Troop Season 1 Limited | Information & communication | 2020 |
| THE Courtyard Garden Lodge Holywood Limited | Households | 2019 |
| THE Cove Gift Shop Ltd | Wholesale & retail | 2012 |
| THE Crafty Balloon Co Limited | Wholesale & retail | 2025 |
| THE Crossle Car Company Limited | Manufacturing | 2012 |
| THE CUE Zone Limited | Arts & recreation | 2025 |
| THE Dormie House Limited | Financial services | 2023 |
| THE Eleos Project Limited | Health & social care | 2025 |
| THE Embankment Management Company (NI) Limited | Real estate | 2009 |
| THE Four Horsemen (N.I.) Limited | Hospitality | 2015 |
| THE Happy Property Group Limited | Hospitality | 2018 |
| THE Harbourview Hotel Limited | Hospitality | 2024 |
| THE Headache and Migraine Centre Ltd | Health & social care | 2023 |
| THE Pavillion Partnership N. Ireland LP | | 2004 |
| THE Perfect Trip Consultancy Ltd | Administrative & support | 2024 |
| THE Railway House Hotel Limited | Real estate | 2024 |
| THE Really Handy Tradesmen Limited | Construction | 2014 |
| THE Rugby Archive Ltd | Manufacturing | 2026 |
| THE Suresh Tharmaratnam Care and Humanity Foundation | Health & social care | 2025 |
| Theeventspros.Com Ltd | Administrative & support | 2022 |
| Therapy for YOU Ltd | Health & social care | 2024 |
| Thirty Five DP LLP | | 2022 |
| Thirty Five DP Topco Ltd | Professional & scientific | 2019 |
| Thol and Think Productions Ltd | Information & communication | 2022 |
| Thompson Lacuna Limited | Construction | 2021 |
| Thorntons Farms Limited | Agriculture & fishing | 2016 |
| Threshold Films Ltd | Information & communication | 2026 |
| Thrive CSR Group Limited | Financial services | 2023 |
| Thrive CSR Limited | Information & communication | 2015 |
| Titanic Distillers Belfast Ltd | Wholesale & retail | 2018 |
| Titanic GIN Ltd | Manufacturing | 2018 |
| Titanic Vodka Ltd | Manufacturing | 2018 |
| Tnfm Catering Ltd | Hospitality | 2025 |
| Together UK Limited | Other services | 2022 |
| Tolemics Ltd | Information & communication | 2014 |
| Tooley Street LLP | | 2017 |
| Torwhin Limited | Wholesale & retail | 2007 |
| Tosa Properties Ltd | Real estate | 2021 |
| Transition Energy Limited | Professional & scientific | 2015 |
| Travel News Limited | Information & communication | 2019 |
| Triberg Limited | Wholesale & retail | 1992 |
| Tropical Investment Ltd | Real estate | 2021 |
| Trustland Property Management & Investment Limited | Real estate | 2023 |
| Tsudoi Ltd | Information & communication | 2024 |
| TSV Thompson Specialist Vehicles Ltd | Wholesale & retail | 2019 |
| Ttoperations Limited | Professional & scientific | 2025 |
| Tullcan Global Ltd | Wholesale & retail | 2022 |
| Tullynagardy Apartments Management Company Limited | Real estate | 2014 |
| Turnbull Developments Limited | Construction | 1982 |
| Twisel Properties Ltd | Real estate | 2024 |
| Tyberan Limited | Professional & scientific | 2018 |