| Scaffolding Industry Management Information (and) Advice Nexus Limited | Administrative & support | 2020 |
| Scar Group Limited | Administrative & support | 2023 |
| Scenario Marketing Ltd | Professional & scientific | 2016 |
| Scientific Insights Limited | Professional & scientific | 2011 |
| Scrub Nelly Limited | Wholesale & retail | 2023 |
| Seal Travel Ltd | Administrative & support | 2024 |
| Sealand Hand Car Wash Ltd | Other services | 2021 |
| Seas Training Ltd | Administrative & support | 2025 |
| Seeka Sport Limited | Manufacturing | 2020 |
| Sefa's Hairdresser Ltd | Other services | 2020 |
| Semil Trans Ltd | Transport & logistics | 2026 |
| Senepicus Ltd | Transport & logistics | 2021 |
| Sequoia Joinery Limited | Construction | 1997 |
| Seren Business Solutions Ltd | Professional & scientific | 2021 |
| Servicebase Building Services Ltd | Construction | 2022 |
| SET Software Solution Ltd | Information & communication | 2023 |
| SEVEN11SYSTEMS Limited | Information & communication | 2020 |
| SFC 2012 Ltd | Other services | 2012 |
| SG Paraplanning Ltd | Agriculture & fishing | 2013 |
| Shalom Kebab & Curry Limited | Hospitality | 2019 |
| Shehaj Fitness Ltd | Wholesale & retail | 2021 |
| Shellhex Ltd | Information & communication | 2025 |
| Shhh Strips Ltd | Wholesale & retail | 2025 |
| Shotton Curry House Limited | Hospitality | 2025 |
| Shotton Cycles Ltd | Wholesale & retail | 2012 |
| Shotton Mill Limited | Manufacturing | 2020 |
| Shotton Phones Ltd | Wholesale & retail | 2024 |
| Shotton Pizza & Kebab Stop Ltd | Hospitality | 2023 |
| Shotton Pizza Limited | Hospitality | 2026 |
| Shotton Travel Ltd | Transport & logistics | 2025 |
| Shotton Valeting Ltd | Administrative & support | 2024 |
| Shrimpton & Fletcher Limited | Professional & scientific | 1959 |
| Sidelake Property Limited | Real estate | 2020 |
| Silverstone Autosport Limited | Extraterritorial | 2005 |
| SIP Stop Limited | Wholesale & retail | 2025 |
| Sisu Tattoo Lounge Ltd | Other services | 2023 |
| SJK Pamper Palace Ltd | Other services | 2025 |
| SJL Growthtech Consultancy Ltd | Information & communication | 2023 |
| SJS Accounting Services Limited | Professional & scientific | 2025 |
| Skycert Ltd | Professional & scientific | 2025 |
| Skyliner Media Ltd | Transport & logistics | 2020 |
| Skyner Engineering Services Limited | Manufacturing | 2017 |
| Skyner Enterprises Limited | Financial services | 2025 |
| Skyraz Solutions Limited | Professional & scientific | 2024 |
| SLD K9 Ltd | Other services | 2025 |
| Slrl Ltd | Professional & scientific | 2015 |
| Smaczek RM Holding Ltd | Financial services | 2025 |
| Smaczek RM Ltd | Wholesale & retail | 2018 |
| Smart Giraffe Virtual Assistant Services Ltd | Administrative & support | 2018 |
| Smart Waste Solutions Ltd | Water & waste | 2014 |
| Smash and Spice Ltd | Hospitality | 2026 |
| Smash'D IT Deeside Ltd | Hospitality | 2023 |
| Smircare Ltd | Information & communication | 2019 |
| Snug Stays Ltd | Real estate | 2019 |
| Soap Opera Laundry Ltd | Other services | 2023 |
| Sofius Designs Ltd | Professional & scientific | 2026 |
| Solace Plates Limited | Professional & scientific | 2026 |
| Solstice International Limited | Financial services | 2025 |
| Sourced Goods Limited | Wholesale & retail | 2023 |
| Southgate Management Services Ltd | Administrative & support | 2024 |
| SP Retailer Ltd | Wholesale & retail | 2024 |
| SPB Solutions Ltd | Professional & scientific | 2023 |
| Spencers GAS Care Limited | Manufacturing | 1988 |
| Spencers Homes Limited | Manufacturing | 2001 |
| Spencers Plumbing & Heating Supplies Limited | Construction | 1994 |
| Spices Shotton Limited | Hospitality | 2022 |
| Sportsbook Limited | Arts & recreation | 2007 |
| Sprayworx Autobody Repairs Ltd | Wholesale & retail | 2025 |
| Spread-A-Bale Limited | Manufacturing | 2005 |
| SRC (Chester) Ltd | Construction | 2019 |
| SRM Staff Ltd | Hospitality | 2015 |
| ST Marks Mews (Connahs Quay) Management Company Ltd | Households | 2017 |
| ST Philopater Foods Ltd | Hospitality | 2025 |
| Stand Correct Ltd | Wholesale & retail | 2026 |
| Starlight Science Limited | Professional & scientific | 2022 |
| Station Road Deeside Mini Market Limited | Wholesale & retail | 2024 |
| Steadfast Payroll Ltd | Professional & scientific | 2025 |
| Stefan & Mathias Ltd | Real estate | 2025 |
| Stephan (UK) Limited | Wholesale & retail | 2003 |
| Sterling Deeside Limited | Professional & scientific | 2010 |
| Steve Hopewell Holdings Limited | Wholesale & retail | 2002 |
| Stevenage Modern Marketing Ltd | Information & communication | 2019 |
| Steves Transport Solutions Limited | Transport & logistics | 2008 |
| Stewart Mackenzie Ltd | Manufacturing | 2018 |
| STG Construction Limited | Construction | 2018 |
| Stonegrass Ltd | Hospitality | 2020 |
| Stopping Power Ltd | Wholesale & retail | 2025 |
| Strahan III Limited | Administrative & support | 2017 |
| Straight to the Summit Ltd | Arts & recreation | 2023 |
| Stringfellows Home Improvements Limited | Construction | 2021 |
| Suntime Properties Limited | Construction | 1971 |
| Superior Bathroom and Wetrooms Limited | Construction | 2020 |
| Surecalm Healthcare Holdings Limited | Professional & scientific | 2009 |
| Surecalm Healthcare Ltd | Health & social care | 2010 |
| Surecalm Pharmacy Limited | Health & social care | 2010 |
| Susan Liles Consultancy Limited | Professional & scientific | 2025 |
| SW Coach Travel Limited | Transport & logistics | 2024 |
| Sweet Jessi Coffee & Cakes Ltd | Hospitality | 2018 |
| Synergy Business Consultants Limited | Information & communication | 2003 |
| Synergy Stem CIC | Education | 2025 |