| SAN Roque Investments Limited | Financial services | 2025 |
| Sancta Maria 2 Ltd | Agriculture & fishing | 2026 |
| Sandbank Holiday Lets Ltd | Hospitality | 2019 |
| Sandra Baird Optometrist Limited | Health & social care | 2018 |
| Sands and Toner Mangagement Company Limited | Administrative & support | 2002 |
| Santinotech Ltd | Information & communication | 2018 |
| Sapphoc Ltd | Administrative & support | 2018 |
| Sarah Macauley Architect Ltd | Professional & scientific | 2020 |
| Sarc Contracts Ltd | Construction | 2013 |
| Sarcon NO. 30 Limited | Professional & scientific | 1996 |
| Satg Ltd | Information & communication | 2025 |
| Saul Acres Management Company Limited | Households | 2018 |
| Saul Manor Management Company Limited | Households | 2019 |
| Savage & Whitten Wholesale Ltd | Wholesale & retail | 2000 |
| Savage Engineering & Coachworks Ltd | Manufacturing | 2003 |
| Savage GFE Ltd | Manufacturing | 2021 |
| Savage Stylists Ltd | Other services | 2015 |
| Savages Home Bakery Ltd | Manufacturing | 2005 |
| Savatek Solutions Ltd | Professional & scientific | 2025 |
| Save Oils Ltd | Wholesale & retail | 2015 |
| Sawhill Park Management Co Ltd | Households | 2011 |
| SB Marketing Limited | Professional & scientific | 2017 |
| SB Quality Solutions NI Ltd | Manufacturing | 2024 |
| Sbmg Barbershop Ltd | Other services | 2025 |
| SCA Haulage Ltd | Transport & logistics | 2012 |
| Scafell Freeholds Limited | Real estate | 1974 |
| Scamp and PAW Ltd | Manufacturing | 2025 |
| Scarva Buying Group Ltd | Agriculture & fishing | 2002 |
| SCC Brick & Blocklaying Solutions Ltd | Construction | 2017 |
| Sccl Developments Limited | Construction | 2016 |
| Scientific & Technical Engineering Partnership Ltd | Professional & scientific | 2011 |
| Scissor Sister Camlough Ltd | Other services | 2014 |
| Scissor Sister Limited | Other services | 2025 |
| SCM & Sons Ltd | Transport & logistics | 2021 |
| Scodo Equine Ltd | Agriculture & fishing | 2024 |
| Scope Contracts (NI) Limited | Construction | 2013 |
| Scope Living Ltd | Financial services | 2025 |
| Scotia Technology Holdings Limited | Extraterritorial | 2017 |
| Scotia Technology Properties Ltd | Real estate | 2024 |
| Scotia Technology UK Limited | Professional & scientific | 2017 |
| SD Consultancy (NI) Limited | Professional & scientific | 2005 |
| SD Independent Trading Limited | Wholesale & retail | 2025 |
| SD Property N.I. Limited | Real estate | 2025 |
| SD Roofing & Sons Ltd | Construction | 2026 |
| Sdhuk Midco Ltd | Hospitality | 2021 |
| Sdhuk Operator Ltd | Hospitality | 2020 |
| SDJ Contracts Ltd | Construction | 2022 |
| SE Finnegan Haulage Ltd | Transport & logistics | 2025 |
| Sea Breeze Rental Ltd | Hospitality | 2024 |
| Sea Distribution Imports & Exports Ltd | Transport & logistics | 2020 |
| Sea Energies Offshore Marine Limited | Energy | 2016 |
| Sea Source Off-Shore Ltd | Other services | 2011 |
| Sea Source Processing Ltd | Agriculture & fishing | 2014 |
| Seacrest Property Management Limited | Hospitality | 1997 |
| Seafields Court Warrenpoint Management Company Limited | Households | 2005 |
| Seafort House Limited | Health & social care | 2013 |
| Seafront House Management Company (Rostrevor) Limited | Extraterritorial | 2001 |
| Seahaven Newcastle Management Ltd | Households | 2023 |
| Sealed Tight Solutions Ireland Ltd | Manufacturing | 2018 |
| Seamark Express L.P. | | 2017 |
| Seamount Developments Limited | Construction | 2020 |
| Seamount Management Limited | Households | 1999 |
| Sean Callan & Associates Ltd | Professional & scientific | 2016 |
| Sean Farrell Contracts Ltd | Professional & scientific | 2015 |
| Sean Loughran Limited | Transport & logistics | 2016 |
| Sean Murphy Property LET Limited | Real estate | 2012 |
| Sean Murray Electrical Ltd | Construction | 2023 |
| Sean Sloan Contracts Limited | Construction | 2014 |
| Seapark Consultancy UK Limited | Information & communication | 2023 |
| Seapark Industrial L.P. | | 2015 |
| Seapoint Enterprises Limited | Financial services | 2018 |
| Seastone Wholesale Ltd | Wholesale & retail | 2026 |
| Seatown Court Management Company Limited | Households | 2022 |
| Seaview Nineteen Ltd | Hospitality | 2025 |
| Seaview Travel Limited | Transport & logistics | 2011 |
| Seaview Vehicle Consultancy Ltd | Wholesale & retail | 2024 |
| Second Story Developments Ltd | Real estate | 2025 |
| Second Story Holdings Ltd | Financial services | 2025 |
| Secure Home Windows & Doors Ltd | Wholesale & retail | 2009 |
| Secureshred(Ni) Limited | Water & waste | 2015 |
| Securi-Cabin UK Ltd | Professional & scientific | 2011 |
| Sedae Construction Consultants Limited | Construction | 2024 |
| Seed Money (NI) Ltd | Professional & scientific | 2025 |
| Seehaven Properties Limited | Construction | 2007 |
| Seek Solutions Limited | Construction | 2023 |
| Selfishbeauty Ltd | Wholesale & retail | 2020 |
| Seno Solutions Ltd | Financial services | 2025 |
| Sensational Swimmers Ltd | Education | 2025 |
| SEO Impact Ltd | Information & communication | 2021 |
| Serene Bean Limited | Hospitality | 2026 |
| SES Servicing Engineering Solutions Ltd | Manufacturing | 2019 |
| Setanta Tyre Supplies Ltd | Wholesale & retail | 2025 |
| Setanta Workwear Ltd | Manufacturing | 2020 |
| Seven Steps Limited | Households | 1992 |
| SEW Construction (N.I.) Limited | Construction | 2019 |
| Sewing Point Ltd | Other services | 2025 |
| SF Electrics Limited | Construction | 2017 |
| SFD Contracts Ltd | Construction | 2025 |
| SFK IT Advisory Services Ltd | Information & communication | 2024 |
| SG Hire Limited | Administrative & support | 2014 |