| Solus Computing Limited | Information & communication | 1997 |
| Solution Factors Limited | Professional & scientific | 2003 |
| Solutionise Consultancy Ltd | Professional & scientific | 2024 |
| Something a BIT Different Ltd | Administrative & support | 2018 |
| Soundesign Broadcast Limited | Administrative & support | 2004 |
| South Central (Essex Street) Management Company Limited | Households | 2023 |
| South Central Treasury Co Ltd | Households | 2024 |
| South Northants Volunteer Bureau | Information & communication | 2004 |
| South Olive Spaces Limited | Real estate | 2025 |
| Southgate Rents Limited | Administrative & support | 1992 |
| Sp&F Ltd | Manufacturing | 2010 |
| Spagbot Games Ltd | Information & communication | 2024 |
| Sparkle & BOO Limited | Wholesale & retail | 2026 |
| Sparkles Cleaning Company Limited | Administrative & support | 2003 |
| Sparkles Commercial Cleaning Ltd | Administrative & support | 2016 |
| Sparkles Properties Limited | Real estate | 2017 |
| Specialist Access Ltd | Construction | 2023 |
| Spectis Ltd | Professional & scientific | 2025 |
| Spencer Micro Limited | Other services | 2010 |
| SPH 521 Limited | Extraterritorial | 2007 |
| Sphrm Limited | Administrative & support | 2015 |
| Spider Blue Ltd | Hospitality | 2019 |
| Spinal Track | Health & social care | 2016 |
| Sports Hall Services Ltd | Manufacturing | 2011 |
| Spotra Limited | Professional & scientific | 2013 |
| Spring Hill Houses Ltd | Agriculture & fishing | 2023 |
| Spyder Club Limited | Administrative & support | 2014 |
| Spyder Events Limited | Administrative & support | 2006 |
| Spyder Motorcycles Limited | Administrative & support | 2017 |
| Spyder Ventures Ltd | Administrative & support | 2011 |
| Sr-Tek Limited | Manufacturing | 2009 |
| SRB Global Solutions Limited | Manufacturing | 2025 |
| SRD Engineering Solutions Limited | Construction | 2021 |
| SSI Schaefer Ltd | Wholesale & retail | 1960 |
| SSI Schaefer Plastics UK Limited | Manufacturing | 2022 |
| ST Barts Media Ltd | Extraterritorial | 2011 |
| ST Giles Home Lighting and Furniture Ltd | Professional & scientific | 2024 |
| ST. Marys Livestock Transport Ltd | Agriculture & fishing | 2011 |
| Stable Fabrication Limited | Manufacturing | 2002 |
| Stamford Cannon (1886) Ltd | Construction | 2014 |
| Stamford Cannon (1905) Ltd | Construction | 2015 |
| Stamford Cannon (NDM) Ltd | Construction | 2021 |
| Stamford Cannon (Northampton) Ltd | Construction | 2020 |
| Stamford Cannon (Thornton) Limited | Real estate | 2012 |
| Stamford Cannon (Wrexham) Ltd | Construction | 2020 |
| Stamford Cannon Investments LLP | | 2012 |
| Stanga Atlantic Limited | Health & social care | 2026 |
| Stanga Limited | Health & social care | 2003 |
| Starkie Enterprises Ltd | Professional & scientific | 2023 |
| Station Holdings Limited | Financial services | 2021 |
| Status Grand Prix Engineering Limited | Arts & recreation | 2009 |
| Status GT Racing Limited | Arts & recreation | 2010 |
| STC Aesthetics Ltd | Other services | 2023 |
| Steadfast Capital Group Ltd | Financial services | 2025 |
| Steamwork Film Limited | Information & communication | 2016 |
| Stefano Jewellery Ltd | Wholesale & retail | 2024 |
| Steiner Friends Limited | Health & social care | 1998 |
| Steiner Therapeutics Limited | Extraterritorial | 2019 |
| Step IT Services Limited | Information & communication | 2007 |
| Stephen Jones Consulting Ltd | Professional & scientific | 2024 |
| Steve Corbett Ltd | Wholesale & retail | 2012 |
| Steven Wills Ltd | Extraterritorial | 2024 |
| Stick of Rock Limited | Professional & scientific | 2010 |
| Stickland Property Investment Ltd | Real estate | 2025 |
| Stilp Property Developments Ltd | Real estate | 2018 |
| Stirling Psychology Ltd | Professional & scientific | 2025 |
| Stock Engineering Services Limited | Professional & scientific | 2018 |
| Stone Wolf Guitars Ltd. | Manufacturing | 2013 |
| Stony Service Centre Limited | Wholesale & retail | 2005 |
| Stopalert Limited | Information & communication | 2015 |
| Stopptech Limited | Professional & scientific | 2020 |
| Storey Motorsport Limited | Arts & recreation | 2026 |
| Storey Watch Company Limited | Professional & scientific | 2022 |
| Strangford Property Consultancy Limited | Other services | 2001 |
| Stratford Residential Lettings Ltd | Real estate | 2008 |
| Stratford Residential Property Ltd | Real estate | 2008 |
| Stratfords DRY Cleaners (Towcester) Ltd | Other services | 2025 |
| Stratos Performance Solutions Ltd | Information & communication | 2026 |
| Streamlined Limited | Professional & scientific | 2016 |
| Strider Holdings Limited | Financial services | 2023 |
| Stuart Robert Construction Limited | Construction | 2006 |
| Studio RHD Limited | Professional & scientific | 2019 |
| Studio Sofia Limited | Professional & scientific | 2022 |
| Studycat Publications Limited | Information & communication | 2019 |
| Subs Solutions Ltd | Administrative & support | 2019 |
| Suki Holdingz Limited | Financial services | 2025 |
| Suku Saunas Ltd | Other services | 2023 |
| Summer Street Spirits Ltd | Wholesale & retail | 2021 |
| Summit TV Ltd | Information & communication | 2025 |
| Sunmaker Ltd | Real estate | 2015 |
| Sunseeker Developments Ltd | Construction | 2025 |
| Super Magic Bean Limited | Wholesale & retail | 2018 |
| Super Turismo UK Limited | Wholesale & retail | 2011 |
| Supercar Fest Ltd | Administrative & support | 2021 |
| Superscan 360 Limited | Professional & scientific | 2013 |
| Survinspect Ltd | Professional & scientific | 2025 |
| Sussi Yami Ltd | Wholesale & retail | 2026 |
| SW21 Ltd | Financial services | 2021 |
| Swallowfields Stud Limited | Other services | 2017 |
| Swan Valley Office Village Management Company Limited | Real estate | 2007 |