| Silk (NW) Limited | Other services | 2019 |
| Silva & Sons Ltd | Wholesale & retail | 2014 |
| Silva (Chirk) Limited | Agriculture & fishing | 1998 |
| Silva (Napton) Limited | Real estate | 2025 |
| Silva Carus Siberians Ltd | Agriculture & fishing | 2021 |
| Silva Recycling Limited | Water & waste | 2004 |
| Silvatree Exchange Ltd | Administrative & support | 2020 |
| Silve Ltd | Transport & logistics | 2021 |
| Silvergate Plastics Limited | Extraterritorial | 2008 |
| Simax Property NW Ltd | Real estate | 2025 |
| Simkaz Property Limited | Construction | 2024 |
| Simon & Nicola's Properties Limited | Real estate | 2019 |
| Simon O'Rourke Ltd | Arts & recreation | 2008 |
| Simon Whittingham Limited | Construction | 2015 |
| Simons Brothers Limited | Construction | 2014 |
| Simple Suites Ltd | Real estate | 2017 |
| Simpler Shopping Limited | | 1991 |
| Sinclair Developments Limited | Extraterritorial | 1995 |
| Sinevo Limited | Information & communication | 2025 |
| Sips Kits Limited | Manufacturing | 2023 |
| Sirens of Sereia Ltd | Arts & recreation | 2025 |
| Siros Investments Limited | Information & communication | 2023 |
| SIS Consultations Limited | Health & social care | 2023 |
| Sitastruct Limited | Construction | 1993 |
| Site Solutions Engineering Ltd | Construction | 2011 |
| Site Solutions Hire Limited | Administrative & support | 2015 |
| Site Solutions Supplies Ltd | Wholesale & retail | 2015 |
| Sivamatha Ltd | Wholesale & retail | 2023 |
| SIW Consultancy Ltd | Manufacturing | 2014 |
| SK Aerotech Ltd | Manufacturing | 2022 |
| SK Cancercare Limited | Health & social care | 2025 |
| SK Engineering & Fabrication Ltd | Manufacturing | 2026 |
| SK Joinery Solutions Ltd | Construction | 2019 |
| Skale Limited | Professional & scientific | 2013 |
| Skanda Acoustics Limited | Wholesale & retail | 2005 |
| Skellon Events & Productions Ltd. | Hospitality | 2020 |
| Ski-Champoluc (Holdings) Ltd | Financial services | 2026 |
| Ski-Champoluc Ltd | Hospitality | 2021 |
| Skill Hive C.I.C. | Professional & scientific | 2015 |
| Skin Aesthetics (NW) Limited | Other services | 2016 |
| Skin Rejuvenation and Aesthetics Ltd | Health & social care | 2020 |
| Skinmedika Limited | Wholesale & retail | 2023 |
| Skinplicity Aesthetics by Alex Ltd | Other services | 2026 |
| Skippy FC Limited | Arts & recreation | 2024 |
| Sky Living Limited | Real estate | 2017 |
| Skydive Tilstock Freefall Club Ltd | Arts & recreation | 2015 |
| Skydive Zone Ltd | Arts & recreation | 2003 |
| Slackers Entertainment Limited | Extraterritorial | 2007 |
| Slates and Ladders Roofing and Building Ltd | Construction | 2026 |
| SLC Care Agency Limited | Health & social care | 2008 |
| SLC Care Limited | Wholesale & retail | 2005 |
| SLC Property Business Ltd | Real estate | 2025 |
| Sliding Systems Group Limited | Manufacturing | 2012 |
| SLL Plant and Quarry Training Services Ltd | Education | 2003 |
| SLO Interiors Ltd | Construction | 2022 |
| SLP Integrity Solutions Limited | Professional & scientific | 2026 |
| SLR Joinery Contractors Ltd | Construction | 2023 |
| SLR Joinery Ltd | Construction | 2009 |
| SLR Services (WXM) Limited | Other services | 2022 |
| SLS Travel Ltd | Transport & logistics | 2026 |
| SM Logistics Ltd | Transport & logistics | 2018 |
| Smart Care Training Limited | Extraterritorial | 2010 |
| Smart Grass Factory Outlet Ltd | Wholesale & retail | 2019 |
| Smart Little Movers Ltd | Health & social care | 2014 |
| Smart Placements Group Ltd | Administrative & support | 2019 |
| Smart Print & Labelling Limited | Wholesale & retail | 2004 |
| Smart Trendz Limited | Wholesale & retail | 2017 |
| Smart Works Solutions Ltd | Manufacturing | 2025 |
| Smartcleaning Solutions Ltd | Construction | 2000 |
| Smarter Business Solutions Limited | Extraterritorial | 2022 |
| Smartinvesthomes Limited | Financial services | 2025 |
| Smarts Electrical Services Limited | Construction | 2014 |
| Smarttrades (Wales) Limited | Wholesale & retail | 2012 |
| SMARTTRENDS21 Ltd | Wholesale & retail | 2026 |
| Smashed IT Wrexham Ltd | Hospitality | 2024 |
| Smashi Wrexham Ltd | Hospitality | 2025 |
| SMC Electrical Services Ltd | Construction | 2007 |
| SMD Engineering Ltd | Construction | 2020 |
| SMD Retail Limited | Wholesale & retail | 2003 |
| Sminty Limited | Professional & scientific | 2009 |
| Smith Grant Limited Liability Partnership | | 2001 |
| Smithfield Foods Ltd | Hospitality | 2025 |
| Smiths Freight Solutions Limited | Transport & logistics | 2009 |
| Smithy Garage Hope Ltd | Wholesale & retail | 2019 |
| SN Electrical Wrexham Ltd | Construction | 2025 |
| SNA Healthcare Limited | Real estate | 2023 |
| SND Builders Limited | Construction | 2021 |
| Snnv Ltd | Hospitality | 2026 |
| Snowdon Solutions Ltd | Administrative & support | 2021 |
| Snowdon Talent Limited | Administrative & support | 2018 |
| Soar Chapel Management Limited | Other services | 2009 |
| Social Maverick Media Limited | Information & communication | 2025 |
| Sodajo Limited | Administrative & support | 2009 |
| Soft Play Global Ltd | Wholesale & retail | 2025 |
| Softplay Supplies Limited | Construction | 2023 |
| Soil Landscapes Limited | Health & social care | 2024 |
| Solartech Installations Ltd | Construction | 2012 |
| Soleil Foodservice Limited | Wholesale & retail | 2004 |
| Solo Rail Consultancy Ltd | Professional & scientific | 2020 |
| Solution Housing Management Limited | Real estate | 2020 |