| Stewart Medical Services Limited | Health & social care | 2023 |
| Stewarton Barbers Ltd | Other services | 2022 |
| Stewarton Fresh Mart Ltd | Wholesale & retail | 2025 |
| Stewarton Nails Limited | Other services | 2026 |
| Stewarton New Style Ltd | Other services | 2021 |
| Stewarton Properties Ltd | Real estate | 2024 |
| Stewarton Style Barbers Ltd | Other services | 2018 |
| Stewarton Supermarket Ltd | Wholesale & retail | 2025 |
| Stewarton Taverns Limited | Hospitality | 2025 |
| Stewarton Vapes Limited | Wholesale & retail | 2026 |
| Stewarts Residentials Limited | Real estate | 2017 |
| Stiggy Motorsport Ltd | Extraterritorial | 2009 |
| Stillsource Ltd | Professional & scientific | 2025 |
| Stirling Park LLP | | 2002 |
| Stockingbridge Ltd | Financial services | 2014 |
| Storage Space Ayrshire Limited | Real estate | 2023 |
| Strata Property Factors Ltd | Real estate | 2026 |
| Strathdee Property Holdings Limited | Real estate | 2022 |
| Strathearn Property Group Ltd | Real estate | 2024 |
| Strathvac Ltd | Administrative & support | 2016 |
| Strikesmart Ltd | Professional & scientific | 2025 |
| Stuart Graham Haulage Limited | Transport & logistics | 2010 |
| Stuart Management Consultancy Ltd | Professional & scientific | 2021 |
| Studio 2112 Ltd | Other services | 2026 |
| Studio ONE18 Ltd | Other services | 2024 |
| Studystreaks Ltd | Information & communication | 2025 |
| Subtle Advantage Limited | Professional & scientific | 2017 |
| Sunken City Ltd | Wholesale & retail | 2025 |
| Sunrise Kilmarnock Limited | Hospitality | 2025 |
| Sunset Entertainment Ltd | Information & communication | 2013 |
| Superlative Libations Company Limited | Hospitality | 2025 |
| Supreme Clean Ayrshire Ltd | Construction | 2025 |
| Sure Leasing Ltd | Administrative & support | 2022 |
| Susie & SAM Limited | Wholesale & retail | 2013 |
| Sustainability Allsorts Ltd | Professional & scientific | 2020 |
| SVY 2 Limited | Financial services | 2024 |
| SVY Limited | Financial services | 2019 |
| SW Electrical (Scotland) Ltd | Manufacturing | 2016 |
| Sweet Jane Bakehouse Ltd | Manufacturing | 2024 |
| SWG Management Limited | Professional & scientific | 2018 |
| Swiftify Limited | Wholesale & retail | 2025 |
| Swodle Ltd | Information & communication | 2018 |
| Syke Feeds Ltd | Financial services | 2018 |
| Sylora Advisory Group Ltd | Professional & scientific | 2026 |
| Symington Community Projects Limited | Administrative & support | 2003 |
| Symington Convenience Store Ltd. | Wholesale & retail | 2015 |
| Symple Landscapes Limited | Administrative & support | 2017 |
| T & L Lets Ltd | Real estate | 2019 |
| T and D Incorporate Ltd | Manufacturing | 2019 |
| T Coaching Limited | Health & social care | 2021 |
| T M Architectural & Building Services Ltd | Construction | 2015 |
| T W Smith Services Limited | Other services | 2025 |
| T&Co Limited | Hospitality | 2012 |
| T&F Consultancy Services Ltd | Administrative & support | 2025 |
| T&J Utilities Ltd | Construction | 2023 |
| T&M Utility Contracts Limited | Construction | 2023 |
| T&M Virtual Office Support Limited | Administrative & support | 2025 |
| Tada Productions Ltd | Arts & recreation | 2013 |
| TAF Steel Ltd | Construction | 2021 |
| Taigh Property Limited | Real estate | 2024 |
| Taliia Bakehouse Ltd | Manufacturing | 2025 |
| Tannahill Furniture Ltd | Wholesale & retail | 2013 |
| Tannlin Group Limited | Professional & scientific | 2013 |
| Tannlin Holdings Limited | Financial services | 2024 |
| Tannlin Technology Limited | Manufacturing | 2011 |
| Tannlin UK Limited | Manufacturing | 2006 |
| Tarmacadam Solutions (Scot) Ltd | Construction | 2020 |
| Tashatom Limited | Health & social care | 2022 |
| Tastie's Maintenance & Auto Repairs Ltd | Wholesale & retail | 2020 |
| Taylor Fisher Limited | Hospitality | 2004 |
| TB 11 Limited | Transport & logistics | 2021 |
| TBS Eshop Ltd | Wholesale & retail | 2023 |
| TCJ Vehicle Builder Limited | Manufacturing | 2014 |
| TCS Decor Services Ltd | Construction | 2023 |
| TCS Response Ltd | Construction | 2011 |
| TDT Morrison Ltd | Financial services | 2026 |
| Team Tumi Fitness - TTF Ltd | Other services | 2022 |
| Technical Ventures Ltd. | Information & communication | 1996 |
| TEK Engineering Ltd | Manufacturing | 2026 |
| Telfer Tavern Limited | Hospitality | 2023 |
| Templehill Dental Surgery Limited | Health & social care | 2019 |
| Templeton Psychology Services Ltd | Health & social care | 2022 |
| Terra Firma Flooring Limited | Construction | 2006 |
| Terra Trenchless UK Ltd | Construction | 2026 |
| TG Civils and Brickwork Ltd | Construction | 2023 |
| TGH (Dundonald) Limited | Hospitality | 2025 |
| Thai Cuisine (Oban) Limited | Hospitality | 2025 |
| THE Auchans Trading Company Limited | Hospitality | 2020 |
| THE Balerno Inn Ltd | Hospitality | 2019 |
| THE Blane Ltd | Real estate | 2026 |
| THE Blane Trading Co Ltd | Wholesale & retail | 2026 |
| THE Boiler Repair Guys Ltd | Construction | 2019 |
| THE Book Nook Stewarton Ltd | Wholesale & retail | 2020 |
| THE Brew Cafe Ltd | Hospitality | 2019 |
| THE Bully Buddy Ltd | Other services | 2025 |
| THE Bungalow Store Limited | Wholesale & retail | 2019 |
| THE Cairns Group Ltd | Hospitality | 2020 |
| THE Carpet Warehouse (Kilmarnock) Limited | Wholesale & retail | 2018 |
| THE Cheesecake GUY (Kilmarnock) Ltd | Wholesale & retail | 2021 |
| THE Chilton Group Ltd | Real estate | 2025 |