| SG International Services LP | | 2020 |
| SG Scaffolding Limited | Construction | 2010 |
| SG Tyre Wholesales Ltd | Wholesale & retail | 2019 |
| SGR Ecomm Ltd | Wholesale & retail | 2010 |
| Sgrc Limited | Construction | 2025 |
| Shabra Group NI Limited | Water & waste | 2025 |
| Shackleton Events Limited | Arts & recreation | 2017 |
| Shacon Farms Ltd | Extraterritorial | 2016 |
| Shacon Ltd | Construction | 2016 |
| Shane Mcardle Plastering Ltd | Construction | 2022 |
| Shanemcnabb Ltd | Construction | 2019 |
| Shania Mackin Interiors Limited | Wholesale & retail | 2022 |
| Shanlieve Stone Ltd | Mining & quarrying | 1997 |
| Shanroe Engineering Services Ltd | Professional & scientific | 2025 |
| Shanroe Service Station Ltd | Wholesale & retail | 2021 |
| Shaped by Shan Ltd | Education | 2024 |
| Shared Seas CIC | Arts & recreation | 2025 |
| Sharkey Sloan Project Services Ltd | Professional & scientific | 2023 |
| Sharpz Studio Ltd | Other services | 2025 |
| Shaughan Plant Hire Ltd | Administrative & support | 2018 |
| Shaughan Quarries Limited | Mining & quarrying | 1996 |
| Shauna Murray Ltd | Arts & recreation | 2025 |
| Shean Finance Limited | Financial services | 2026 |
| Shean Mechanical Contracts Ltd | Construction | 2023 |
| Shean Spirits Ltd | Manufacturing | 2023 |
| Sheds & Welds Ltd | Manufacturing | 2024 |
| Sheepbridge Newry Ltd | Real estate | 2021 |
| Sheeptown Estates Ltd | Financial services | 2023 |
| Sheet FAB Ltd | Manufacturing | 2025 |
| Sheetrim Developments Ltd | Real estate | 2018 |
| Sheetrim Transport Limited | Transport & logistics | 2015 |
| Shefit Ltd | Arts & recreation | 2025 |
| Shelbourne Cars Ltd | Other services | 2017 |
| Shelbourne Financial Solutions Ltd | Financial services | 2015 |
| Shelbourne Properties Newry Ltd | Real estate | 2015 |
| Shelbridge Ltd | Households | 2018 |
| Shelf Company (NO 3) Limited | Extraterritorial | 2006 |
| Shellco Seafoods Limited | Manufacturing | 2019 |
| Sheree Properties Limited | Real estate | 2018 |
| Sheric Enterprises Ltd | Other services | 2009 |
| Sheridans Sandwiches Newry Ltd | Hospitality | 2020 |
| Sherkin Technologies UK Limited | Manufacturing | 2015 |
| Sherry & O'Hare Ltd | Construction | 2004 |
| Shields Bricklaying Ltd | Construction | 2017 |
| Shields Medical Limited | Health & social care | 2011 |
| Shindig Promotions (UK) Ltd | Manufacturing | 2022 |
| Shine Tanning and Beauty Ltd | Other services | 2025 |
| Shinn Farms Ltd | Agriculture & fishing | 2020 |
| Ship Street Holdings Limited | Financial services | 2023 |
| SHK Fabrication Ltd | Manufacturing | 2019 |
| Shooter Property Services (Newry) Ltd | Real estate | 2017 |
| Shop Fit (N I ) Limited | Other services | 2004 |
| Shopfit (IRE) Ltd | Other services | 2015 |
| Shopping Deals Ltd | Wholesale & retail | 2025 |
| Shore Plant and Machinery Ltd | Wholesale & retail | 2021 |
| Showes Ltd | Hospitality | 2022 |
| Shriver Price Consulting Limited | Information & communication | 1999 |
| Shriver Price Limited | Professional & scientific | 2011 |
| Sicuralife UK & Ireland Ltd | Information & communication | 2025 |
| Sidewood Assets L.P. | | 2017 |
| Signature Restaurants Limited | | 2007 |
| Signature Studio Limited | Other services | 2012 |
| Signit Signs Ltd | Manufacturing | 2020 |
| Sika Investments Limited | Extraterritorial | 2016 |
| Silcon Contracts Ltd | Construction | 2025 |
| Silence Unmasked Ltd | Information & communication | 2025 |
| Silent Valley Fertilisers Limited | Wholesale & retail | 2020 |
| Silverbridge Harps Community Resource Centre Ltd | Other services | 2023 |
| Silverbridge Plant Hire Ltd | Construction | 2026 |
| Silverbridge Solutions Ltd | Information & communication | 2007 |
| Silverbridge Takeaway Limited | Hospitality | 2017 |
| Silvergate Developments Ltd | Real estate | 2023 |
| Silverhanna Limited | Construction | 2024 |
| Silvervale Developments (NI) Limited | Financial services | 2016 |
| Silvery Light Sailing | Transport & logistics | 2016 |
| Simply Train ME Ltd | Education | 2022 |
| Siobhan Fitzpatrick Limited | Professional & scientific | 2012 |
| SIR Italian Food Limited | Wholesale & retail | 2022 |
| Sisters by the Sea Limited | Wholesale & retail | 2020 |
| Site Crew (N.I.) Ltd | Construction | 2021 |
| Sixsense Sport Ltd | Wholesale & retail | 2024 |
| Sixthirtythree Ltd | Wholesale & retail | 2025 |
| SJ Henderson Fulfilment Ltd | Transport & logistics | 2019 |
| SJ Rental Group Ltd | Households | 2024 |
| Sjar Group Ltd | Real estate | 2022 |
| SJB Plumbing Ltd | Construction | 2022 |
| SJE Electrical Limited | Construction | 2024 |
| SJM Gastro Limited | Health & social care | 2013 |
| Sjom Groundworks Ltd | Construction | 2019 |
| SJR Developments Ltd | Construction | 2014 |
| SJS Bricklaying Ltd | Construction | 2025 |
| SK Legal & Financial Ltd | Professional & scientific | 2024 |
| SK Quality Limited | Manufacturing | 2020 |
| SK Windows Ltd | Manufacturing | 2023 |
| Skeletal Games Limited | Information & communication | 2023 |
| Skeriff Limited | Hospitality | 2018 |
| Skillfull Development LP | | 2015 |
| Skin and Tonic (N.I) Ltd | Other services | 2026 |
| Skin Complete Medical Aesthetics Ltd | Health & social care | 2023 |
| Skin Support Wear Ltd | Wholesale & retail | 2025 |