| Special Needs Today Ltd | Information & communication | 2018 |
| Specialist Insulation Maintenance Limited | Construction | 2007 |
| Specialist Surface Preparation Limited | Construction | 2004 |
| Specialist Surfacing Limited | Construction | 1995 |
| Specs R US Ltd | Wholesale & retail | 2026 |
| Spectrum Engine Repair and Rebuild Ltd | Wholesale & retail | 2025 |
| Speedy Skips Yorkshire Ltd | Administrative & support | 2026 |
| Spellcraft Ltd | Wholesale & retail | 2023 |
| Spelman Butchers Limited | Wholesale & retail | 2009 |
| Sphere Property Solotions Limited | Real estate | 2025 |
| Spice Box (Scunthorpe) Limited | Hospitality | 2026 |
| Spin and Burt's Body Shop Ltd | Wholesale & retail | 2025 |
| Spire Livestock & Machinery Ltd | Wholesale & retail | 2026 |
| SPL Network Ltd | Administrative & support | 2024 |
| Splashrooms Limited | Wholesale & retail | 2004 |
| Splendidsavings Ltd | Wholesale & retail | 2024 |
| Spmb Transport Ltd | Transport & logistics | 2012 |
| Sport Gym Ltd | Wholesale & retail | 2020 |
| Spots & Sparkles Ltd | Manufacturing | 2025 |
| Springbank Real Estate Limited | Real estate | 2016 |
| Springtime Barn Ltd | Wholesale & retail | 2025 |
| Sprinkler-Guard Ltd | Wholesale & retail | 2025 |
| Sprotbrough Campsite Limited | Real estate | 2023 |
| Sprout Safety Advisors Ltd | Professional & scientific | 2014 |
| SQ FT Groundworks Limited | Construction | 2009 |
| Square One Touring Productions Ltd | Information & communication | 2019 |
| Squids in Sea Baits Limited | Wholesale & retail | 2024 |
| SR Cosmetic Services Limited | Health & social care | 2019 |
| SS Driving Ltd | Education | 2025 |
| SS Electrical Services NW Ltd | Construction | 2025 |
| SS Holistic Health Ltd | Health & social care | 2019 |
| SSD Trading Ltd. | Wholesale & retail | 2019 |
| Ssgl Holdings Limited | Real estate | 2023 |
| SSK Food Limited | Hospitality | 2014 |
| SSK Housing Developments Ltd | Real estate | 2024 |
| SSS & NAZ Ltd | Real estate | 2023 |
| SSS Consultant Ltd | Information & communication | 2024 |
| SSS Couriers Ltd | Transport & logistics | 2024 |
| ST Employment Ltd | Wholesale & retail | 2024 |
| ST Johns Chippy Ltd | Hospitality | 2026 |
| ST Lawrence Residential Care Home Ltd | Health & social care | 2021 |
| ST Paul's PRE School Ashby Limited | Education | 2013 |
| ST. James' Court Limited | Households | 1983 |
| Stab Ltd | Administrative & support | 2011 |
| Stacked Suppliments Limited | Health & social care | 2026 |
| Staff Limited | Administrative & support | 2025 |
| Stag Business Solutions Limited | Administrative & support | 2015 |
| Stahlbrite Ltd | Wholesale & retail | 2019 |
| Stalu Property Ltd | Real estate | 2024 |
| Stanage Singh Consulting Limited | Health & social care | 2024 |
| Standy's Property Services Ltd | Real estate | 2024 |
| Star Kebab Special Ltd | Hospitality | 2026 |
| Starkey & Brown (Scunthorpe Lettings) Ltd | Real estate | 2020 |
| Starkey & Brown (Scunthorpe) Limited | Real estate | 2012 |
| Stars Kebab & Pizza Ltd | Hospitality | 2024 |
| Startdev Ltd | Information & communication | 2020 |
| Starz House Ltd | Hospitality | 2025 |
| Starz Pizza Ltd | Hospitality | 2025 |
| Starz Plus Pizza Ltd | Hospitality | 2024 |
| Statepalm Limited | Health & social care | 1982 |
| Stather Limited | Wholesale & retail | 2011 |
| Station Road Scunny Car Wash Ltd | Administrative & support | 2025 |
| Station Road Yard Ltd | Financial services | 2025 |
| Staycations Management Ltd | Hospitality | 2026 |
| Steel FM Scunthorpe Ltd | Information & communication | 2020 |
| Steel Services and Trading Ltd | Wholesale & retail | 2023 |
| Steel Town Cafe Limited | Hospitality | 2025 |
| Steel Town Cars Ltd | Wholesale & retail | 2025 |
| Steel Town Competitions Limited | Wholesale & retail | 2025 |
| Steel Town Gym Limited | Other services | 2013 |
| Steeper Controls Limited | Extraterritorial | 2015 |
| Stefan Transporter Ltd | Transport & logistics | 2021 |
| Stefy Ltd | Transport & logistics | 2022 |
| Stemlabpro Ltd | Information & communication | 2026 |
| Stennett Site Services Limited | Construction | 2023 |
| Stephen Clark Insulation Services Limited | Construction | 2017 |
| Stepladder Sound Ltd | Administrative & support | 2025 |
| Steve Farr Consultants Limited | Wholesale & retail | 2019 |
| Steve Halligan Medico-Legal Ltd | Professional & scientific | 2021 |
| Steve Martin Motors Limited | Wholesale & retail | 2014 |
| Stevens Tech Ltd | Information & communication | 2019 |
| Stingaciu Ltd | Transport & logistics | 2022 |
| Stirling Care Solutions Ltd | Health & social care | 2025 |
| Stitchline Limited | Manufacturing | 2002 |
| Stms Marine & Aviation Services Ltd | Professional & scientific | 2026 |
| Stocks Group Limited | Administrative & support | 2002 |
| Stonehewer Data Solutions Limited | Information & communication | 2013 |
| Stones From Holmes Ltd | Wholesale & retail | 2019 |
| Stones Homes Limited | Households | 2002 |
| Stop & Shop Scunthorpe Ltd | Wholesale & retail | 2024 |
| Strauss & Kruger Limited | Extraterritorial | 2017 |
| Strive Sports and Community CIC | Arts & recreation | 2026 |
| Structural Specialists Ltd | Construction | 2013 |
| STS Industrial Limited | Transport & logistics | 1988 |
| STU Barnes Coaching Limited | Professional & scientific | 2024 |
| Stuart Armstrong & Co (Scunthorpe) Limited | Professional & scientific | 2011 |
| Stubbins & Williamson Limited | Manufacturing | 1976 |
| Stubbins Limited | Administrative & support | 2008 |
| Studio 7 Theatre Arts Limited | Other services | 2019 |
| STUDIO11 Content Ltd | Professional & scientific | 2025 |