| Sech Management Limited | Administrative & support | 2012 |
| Self Determine UK Limited | Professional & scientific | 2016 |
| Serra Consultants Ltd | Professional & scientific | 2011 |
| Services Family Ltd | Financial services | 2014 |
| Services Finance Limited | Financial services | 2018 |
| Settestars Limited | Transport & logistics | 2025 |
| Seventy Events Limited | Administrative & support | 2020 |
| SFG Media Ltd | Arts & recreation | 2024 |
| SG Curation SS CV LLP | | 2024 |
| SG Curation SS LLP | | 2024 |
| Shade Hair Studio Ltd | Other services | 2026 |
| Shark and Bear Ltd | Manufacturing | 2024 |
| Sharman Plumbing & Heating Ltd | Construction | 2017 |
| Shaun Veasey Building Contractor Ltd | Construction | 2021 |
| Shekleton Wines Ltd | Wholesale & retail | 2020 |
| Shelleys Poochie Parlour - Stamford Limited | Other services | 2022 |
| Shelley’S Poochie Parlour Mobile Dog Grooming Limited | Other services | 2026 |
| Shelton Sportsturf Drainage Ltd | Manufacturing | 2013 |
| Shft Training Ltd | Arts & recreation | 2025 |
| Shipmeadow Battery Support Limited | Energy | 2024 |
| Shoolin RSK Limited | Real estate | 2024 |
| Shooting Star Film Productions Ltd | Information & communication | 2023 |
| Shrewsbury Nexus Management Company Limited | Households | 2013 |
| Shri Krish Food UK Ltd | Wholesale & retail | 2018 |
| Shri Krish Fuels Ltd | Wholesale & retail | 2018 |
| Siam Homes Ltd | Construction | 2020 |
| Sian Jones Consulting Ltd | Professional & scientific | 2005 |
| Sicosys Ltd | Professional & scientific | 2025 |
| SID Paving and Construction Limited | Construction | 2024 |
| Sidechapel Limited | Financial services | 2016 |
| SIH Services Ltd | Professional & scientific | 2011 |
| Silverbullet PR Ltd | Information & communication | 2006 |
| Silverlane Health Store Ltd | Wholesale & retail | 2017 |
| Simaax Ltd | Professional & scientific | 2026 |
| Simmotech Limited | Professional & scientific | 2012 |
| Simon Worrell Heating Services Limited | Construction | 2026 |
| Simply Land Development Ltd | Construction | 2024 |
| Simply Risk Control Ltd | Information & communication | 2010 |
| Simply Stamford Limited | Wholesale & retail | 2020 |
| Simply-Fi Ltd | Financial services | 2022 |
| Sinda CIC | Professional & scientific | 2026 |
| Sinead Crowe Ltd | Professional & scientific | 2018 |
| Site Electrical Services (Ramsey) Limited | Manufacturing | 1986 |
| Siwik Property Services Limited | Construction | 2020 |
| SIX Degrees Wellness Ltd | Wholesale & retail | 2025 |
| SJ Taylor Property Developments Ltd | Real estate | 2024 |
| Skater Limited | Financial services | 2020 |
| Sketchwing Ltd | Professional & scientific | 2018 |
| SKF Associates Ltd | Professional & scientific | 2023 |
| Skin Within Clinic Limited | Other services | 2023 |
| Sky Blue Advantage Limited | Professional & scientific | 2015 |
| Skyline Cabs of Stamford Ltd | Transport & logistics | 2023 |
| Skywharf Solutions Limited | Information & communication | 2014 |
| SL Property & Surveying Limited | Administrative & support | 2022 |
| Slashbackslash Ltd | Professional & scientific | 2021 |
| Slide Consultancy Ltd | Professional & scientific | 2023 |
| Sloss & Co Ltd | Administrative & support | 2016 |
| Smart FIX Appliances Limited | Other services | 2025 |
| Smarta Property Ltd | Real estate | 2018 |
| Smartfish Europe Limited | Professional & scientific | 2010 |
| SMC Creative Ltd | Information & communication | 2019 |
| SMC PR Ltd | Professional & scientific | 2025 |
| SME Direct Limited | Professional & scientific | 2013 |
| Smile & Print Ltd | Manufacturing | 2025 |
| Smithers of Stamford Limited | Wholesale & retail | 2014 |
| Smrt Group Holdings Limited | Financial services | 2025 |
| Snap Media Services Limited | Professional & scientific | 2016 |
| Snikarts Limited | Arts & recreation | 2015 |
| Snowboy Systems Limited | Professional & scientific | 2010 |
| Snowdens Clinic & Beauty Room Ltd | Health & social care | 2013 |
| SO Scrumptious Ltd | Hospitality | 2019 |
| Soap & Furry Ltd | Other services | 2022 |
| Social Impact Consultants Ltd | Professional & scientific | 2024 |
| Solar Consulting Limited | Professional & scientific | 2015 |
| Solar Power Recovery Limited | Manufacturing | 2021 |
| Solution Media Limited | Professional & scientific | 2016 |
| Sonado Limited | Manufacturing | 2026 |
| Sonder Video Limited | Information & communication | 2017 |
| Sort Engine Ltd | Information & communication | 2025 |
| Southcliffe Technology Limited | Information & communication | 2015 |
| Southorpe Limited | Information & communication | 2010 |
| Southwood Building Services Limited | Construction | 2025 |
| Sovereign Global Holdings Ltd | Wholesale & retail | 2026 |
| Sovereign Property Partners LLP | | 2009 |
| Sowden Wallis Limited | Real estate | 2018 |
| SP Powerworld Ltd | Professional & scientific | 2005 |
| Spaces by Design Limited | Construction | 2020 |
| Spada Services Limited | Professional & scientific | 2025 |
| Sparqz Limited | Education | 2015 |
| Spartan Partners Limited | Real estate | 2015 |
| Special Connexions Limited | Health & social care | 2024 |
| Spectrum Courses Limited | Education | 2019 |
| Speedworks Solutions Ltd | Information & communication | 2022 |
| Speedworks Training Ltd | Arts & recreation | 2013 |
| Spencers Horsebox Hire Ltd | Administrative & support | 2019 |
| Spep Limited | Energy | 2010 |
| SPG DRY Lining Ltd | Construction | 2023 |
| SPG Energy Park 1 Ltd | Real estate | 2025 |
| Spiegl Press Limited | Manufacturing | 2010 |
| Splendid Supplies Ltd | Wholesale & retail | 2024 |