| Saiganesha Ltd | Wholesale & retail | 2020 |
| Sajjad Medical Ltd | Health & social care | 2019 |
| Saltroxs Ltd | Real estate | 2026 |
| SAM Q Properties Ltd | Hospitality | 2024 |
| Samryan Limited | Real estate | 1991 |
| Sandalwood Properties Developments Limited | Real estate | 2024 |
| Sansad Ltd | Hospitality | 2024 |
| Sapphire ICT Services Ltd | Information & communication | 2022 |
| Sarah Zahid Properties Ltd | Real estate | 2022 |
| Sash Consult Ltd | Professional & scientific | 2022 |
| SB Property Solutions Ltd | Construction | 2023 |
| Scanlon Bars Ltd | Hospitality | 2025 |
| Scibase.Ai Limited | Information & communication | 2025 |
| Seacliffe Management Services Limited | Extraterritorial | 2011 |
| Seager Properties Ltd | Real estate | 2021 |
| Seascape Therapies Ltd | Professional & scientific | 2026 |
| Secrets Beauty Ltd | Other services | 2011 |
| Sedimentix Limited | Mining & quarrying | 2018 |
| Self Storage North Wales Ltd | Extraterritorial | 2021 |
| Semantise Ltd | Information & communication | 2018 |
| Seren Medical Limited | Health & social care | 2024 |
| Seymour's Cafe Limited | Hospitality | 2018 |
| SF Parks Ltd | Hospitality | 2010 |
| SF Sunvalley Limited | Hospitality | 2022 |
| Shaftesbury Estates Limited | Real estate | 1995 |
| Shaftesbury House Management Company Limited | Households | 2017 |
| Shaivaa Care Limited | Health & social care | 2021 |
| Shaka Skimboards Limited | Wholesale & retail | 2023 |
| Share Cast Group Ltd | Information & communication | 2026 |
| Shelbourne Hotel Ltd | Hospitality | 2020 |
| Silverfinch Limited | Real estate | 2020 |
| Simon Amey Services Limited | Professional & scientific | 2016 |
| Simon Antony Limited | Information & communication | 2012 |
| Simon Done Plastering Ltd | Construction | 2024 |
| Sitequest Holdings Limited | Financial services | 2014 |
| Sitequest Offices Limited | Construction | 2004 |
| Sixthsense Systems Ltd | Information & communication | 2024 |
| Sjke Building Contractors Limited | Extraterritorial | 2016 |
| Skylar’S Dog Grooming Ltd | Other services | 2025 |
| Skyline Developments (NW) Limited | Real estate | 2021 |
| Small Train Company Limited | Arts & recreation | 2011 |
| Smart Active Limited | Arts & recreation | 2019 |
| Smart Enterprises Limited | Arts & recreation | 2016 |
| Smart Northern Limited | Financial services | 2016 |
| Smart Test Consulting Ltd | Information & communication | 2015 |
| Smokey O'Connor's Limited | Construction | 2007 |
| SND Group Ltd | Agriculture & fishing | 2026 |
| Snowdonia Orthopaedic Services (SOS) Limited | Health & social care | 2013 |
| Snowdonia Services CYF | Real estate | 2017 |
| Snowdonia Silver Ltd | Wholesale & retail | 2025 |
| Snug Hotels Limited | Real estate | 2013 |
| Snug Llandudno Ltd | Hospitality | 2026 |
| Soak by Doris Limited | Wholesale & retail | 2025 |
| Social Impact Consulting Ltd | Professional & scientific | 2012 |
| Solar Access Solutions Ltd | Construction | 2022 |
| Sole & Mare Limited | Hospitality | 2026 |
| Someplace Else CYD Ltd | Hospitality | 2025 |
| Sound Room Retail Limited | Wholesale & retail | 2010 |
| SP International Hospitality Consulting Limited | Professional & scientific | 2016 |
| Spectrum Windows Limited | Construction | 2003 |
| Spencer Hotels Limited | Hospitality | 2001 |
| SPH Accounting Services Limited | Information & communication | 2011 |
| Spoilt for Choice Carpets Limited | Wholesale & retail | 2008 |
| Springholme Care (Anglesey) Limited | Health & social care | 2002 |
| Springholme Limited | Health & social care | 2010 |
| Squad House Ltd | Arts & recreation | 2016 |
| ST Davids Promotions Limited | Arts & recreation | 1996 |
| ST George Muthappan Ltd | Wholesale & retail | 2019 |
| ST Hilarys Limited | Hospitality | 2024 |
| ST. Annes Court a Limited | Households | 1981 |
| ST. Annes Court B Limited | Households | 1981 |
| Stange Inn & Co Limited | Hospitality | 1991 |
| STE Palin Wind Ltd | Professional & scientific | 2026 |
| Steven Winstanley Limited | Construction | 2016 |
| Stockomendation Limited | Information & communication | 2012 |
| Storer Rentals (Llandudno) Limited | Real estate | 2010 |
| Studio K Nails Limited | Other services | 2019 |
| Substation Management Solutions Limited | Administrative & support | 2012 |
| Substation Standby Ltd | Construction | 2025 |
| Summerdown Advisory Limited | Professional & scientific | 2022 |
| Summersalt Ltd | Real estate | 2023 |
| Summit Complex Limited | Hospitality | 2010 |
| Supercandidates Limited | Extraterritorial | 2010 |
| Supporting Hearts Home Care Ltd | Health & social care | 2026 |
| Swed Dental Care Ltd | Health & social care | 2009 |
| T & a Construction (Holyhead) Ltd. | Construction | 2003 |
| T & C Carpets Limited | Wholesale & retail | 2005 |
| T-Cubed Ltd | Professional & scientific | 2008 |
| T.Talbot Limited | Construction | 2025 |
| Tahdah Verified Limited | Information & communication | 2014 |
| Takanui Limited | Wholesale & retail | 2025 |
| TALK2US My Mental Mess Ltd | Other services | 2025 |
| TAN LAN Properties Limited | Real estate | 2020 |
| TAT Enterprises Ltd | Health & social care | 2010 |
| Tavelo Tandems Ltd | Manufacturing | 2024 |
| Taylor Made Homes UK Limited | Extraterritorial | 2002 |
| Taymas Limited | Construction | 2021 |
| Tayna Towers Ltd | Real estate | 2020 |
| TBA Electro Conductive Products Limited | Manufacturing | 2006 |
| TD Dinos Ltd | Hospitality | 2021 |