| Spill Resolve Ltd | Professional & scientific | 2018 |
| Spmck Holdings Ltd | Professional & scientific | 2023 |
| Spoon Street Franchise Ltd | Extraterritorial | 2020 |
| Spoon Street Holdings Ltd | Professional & scientific | 2019 |
| Spoon Street Ltd | Hospitality | 2013 |
| Spori Italiani Limited | Hospitality | 2010 |
| Sport Advice Ltd | Administrative & support | 2019 |
| Sport Linx Limited | Other services | 2017 |
| Sports Association Newry, Down and South Armagh | Other services | 2003 |
| Spring Forest Limited | Other services | 2020 |
| Spring Hill Court Management Limited | Households | 1997 |
| Spring Manor Management Company Ltd | Households | 2018 |
| Spring Meadows Management Company (N.I.) Ltd | Households | 2018 |
| Springfield Meadows Management Company Limited | Households | 2001 |
| Springisland Service Station Ltd | Wholesale & retail | 2014 |
| SPT Bricklaying Ltd | Construction | 2023 |
| SPT Electrical Contracts Ltd | Construction | 2021 |
| Spudz N Co Ltd | Hospitality | 2025 |
| Square Lighting Ltd | Wholesale & retail | 2018 |
| Square Root 81 Ltd | Hospitality | 2024 |
| Square Root Solutions UK Limited | Information & communication | 2023 |
| Squat Jump Limited | Wholesale & retail | 2024 |
| Squeeze Wheatgrass Limited | Manufacturing | 2011 |
| Squirrel One Limited | Real estate | 2020 |
| SR Feeds Limited | Wholesale & retail | 2021 |
| SRB Fortune Limited | Households | 2026 |
| SRC Global Investments Limited | Real estate | 2021 |
| SRM Stone Ltd | Construction | 2015 |
| SS Equine Ltd | Agriculture & fishing | 2022 |
| Ssas Advocates Ltd | Financial services | 2026 |
| Ssgasco Ltd | Professional & scientific | 2011 |
| ST Annes Killough Management Company Limited | Households | 2022 |
| ST Dynamics & Intelligent Autonomous Systems Ltd | Professional & scientific | 2024 |
| ST John Bosco Youth Centre Limited | Arts & recreation | 2023 |
| ST Valeting Services Limited | Wholesale & retail | 2017 |
| ST. Augustine Property Limited | Real estate | 2011 |
| ST. David's - Warrenpoint Limited | Administrative & support | 2000 |
| ST. Malachy's Development Ltd | Real estate | 2018 |
| Stack Dynamics Limited | Information & communication | 2013 |
| Stacked (N.I.) Limited | Information & communication | 2018 |
| Stafford Lynch (N.I.) Limited | Wholesale & retail | 1993 |
| Stagecoach (Northern Ireland) Ltd | Extraterritorial | 2009 |
| Standmill Trading LP | | 2017 |
| Standport Development L.P. | | 2015 |
| Stanford Times Limited | Professional & scientific | 2017 |
| Stanza Holdings (NI) Limited | Financial services | 2020 |
| Stanza Properties (NI) Limited | Real estate | 2020 |
| Star Automotive and Tyres Ltd | Wholesale & retail | 2026 |
| Star BG Car Wash Ltd | Administrative & support | 2025 |
| Starcom Trading L.P. | | 2015 |
| Start Together Limited | Information & communication | 2011 |
| Starwind Construction L.P. | | 2017 |
| Statcroft Plant Hire UK Ltd | Construction | 2019 |
| Stateline Freight Ltd | Transport & logistics | 2023 |
| Statsports Group Limited | Professional & scientific | 2016 |
| Steda Holdings Limited | Wholesale & retail | 2025 |
| Steel Lintels Ireland Ltd | Wholesale & retail | 2012 |
| Steermount Limited | Real estate | 2012 |
| Stefanie M Fishing Company Limited | Agriculture & fishing | 2002 |
| STELLITO21 Ltd | Health & social care | 2022 |
| Stephen Brannigan Physio Ltd | Other services | 2019 |
| Steve Brown & Associates Limited | Professional & scientific | 2011 |
| Steven Campbell Plumbing & Heating Ltd | Administrative & support | 2017 |
| Stevenson Bros Holdings Limited | Financial services | 2020 |
| Stevenson Marine & Supplies Ltd | Wholesale & retail | 2020 |
| STH Consultancy Ltd | Professional & scientific | 2015 |
| Sticky Fingers Arts | Arts & recreation | 2002 |
| Stille Peter Limited | Wholesale & retail | 2024 |
| Stitch Point Limited | Other services | 2023 |
| Stone Bakery Limited | Manufacturing | 2015 |
| Stonebridge Management Company Limited | Real estate | 2005 |
| Stonebridge Mews Management Limited | Households | 2020 |
| Stonebridge Village Apartments (NO2) Management Company Limited | Real estate | 2009 |
| Stonebridge Village Apartments Management Company Limited | Real estate | 2008 |
| Stonefab Ltd | Manufacturing | 2020 |
| Stonerock Properties Ltd | Professional & scientific | 2012 |
| Stonerock Property Holdings Limited | Real estate | 2021 |
| Stonetec Ltd | Manufacturing | 2014 |
| Storagepoint Ltd | Real estate | 2015 |
| Stormway Consulting L.P. | | 2017 |
| Stpv Ltd | Hospitality | 2025 |
| STR Cranes Ltd | Construction | 2026 |
| STR Imaging Ltd | Health & social care | 2023 |
| Strand Head (N.I.) Limited | Professional & scientific | 2014 |
| Strand Head Ltd | Professional & scientific | 2013 |
| Strata FNI Limited | Professional & scientific | 2026 |
| Stratalearn Ltd | Information & communication | 2026 |
| Strategem Ireland Limited | Professional & scientific | 2006 |
| Strawberry Way Developments Limited | Real estate | 2009 |
| Stream Park Management Co. Ltd | Households | 2002 |
| Stream Street Retail Ltd | Wholesale & retail | 2014 |
| Streamlex Trading L.P. | | 2017 |
| Streets Ahead Clothing Ltd | Wholesale & retail | 2006 |
| Strong Fitness Ltd | Arts & recreation | 2021 |
| Studio D (N.I.) Ltd | Other services | 2022 |
| Studio Five Hairdressers Limited | Other services | 2025 |
| Studio One Newry Ltd | Other services | 2025 |
| STUDIO84 Kitchen & Bedroom Ltd | Manufacturing | 2021 |
| Studios Office Group Ltd | Real estate | 2023 |
| Sturgan Ltd | Arts & recreation | 2020 |