| SPO Scaffolding Ltd | Construction | 2014 |
| Sports Ground Development Ltd | Arts & recreation | 2013 |
| Sportsground Support Ltd | Construction | 2020 |
| Spot Cars Limited | Transport & logistics | 2026 |
| Spot on Bookkeeping Ltd | Professional & scientific | 2022 |
| Spot on Thrapston Limited | Administrative & support | 2015 |
| Spot Saviour Ltd | Wholesale & retail | 2023 |
| Spray Wizards Ltd | Construction | 2020 |
| Spreadbury Property Limited | Real estate | 2023 |
| Spring Crop Protection Ltd | Professional & scientific | 2017 |
| Springfield HDT Ltd | Financial services | 2025 |
| Springvale Support Limited | Health & social care | 2025 |
| SPS Elec Ltd | Construction | 2017 |
| SPS Multitrade Limited | Administrative & support | 2019 |
| Spud Shack Ltd | Hospitality | 2023 |
| Sqft Property Ltd | Construction | 2022 |
| Square Media Solutions Ltd | Professional & scientific | 2013 |
| SR Track Limited | Wholesale & retail | 2016 |
| Sreekrish Ltd | Hospitality | 2024 |
| SRG Group Holdings Ltd | Financial services | 2024 |
| Srjg Consulting Ltd | Professional & scientific | 2015 |
| SS Creative Solutions UK Ltd | Information & communication | 2024 |
| SSB Investment Services Limited | Real estate | 2018 |
| SSB Medical Services Limited | Health & social care | 2010 |
| SSP Global Limited | Wholesale & retail | 2026 |
| SSR Associates Ltd | Information & communication | 2010 |
| ST Anthony's Walk Management Company Limited | Households | 2011 |
| ST Bridge Ltd | Hospitality | 2025 |
| ST George's Place (Northampton) Management Company Limited | Professional & scientific | 2000 |
| ST Mary's Church of England VA Primary Academy | Education | 2013 |
| ST Peter's Court (Kettering) Management Company Limited | Real estate | 2005 |
| ST Training Services Ltd | Health & social care | 2019 |
| ST. Neots Bowmen Archery Club | Arts & recreation | 2019 |
| Staatec Limited | Construction | 2023 |
| Stable Properties Limited | Real estate | 2013 |
| Staci's Limited | Hospitality | 2024 |
| Staff Connection Ltd | Administrative & support | 2010 |
| Stage TEC Productions Limited | Arts & recreation | 2018 |
| Stamco Limited | Administrative & support | 2021 |
| Stamford Brands Limited | Wholesale & retail | 2021 |
| Stanair Industrial Door Services Limited | Construction | 1974 |
| Standard Engineering Holdings Limited | Manufacturing | 2019 |
| Standard Engineering Limited | Manufacturing | 1999 |
| Standard Engineering Property Limited | Real estate | 2019 |
| Standard Group Limited | Manufacturing | 2006 |
| Stanion Developers Limited | Construction | 2013 |
| Stanley Wilson Properties Limited | Real estate | 2021 |
| Star Baby Audio Limited | Information & communication | 2025 |
| Star Leon Ltd | Construction | 2020 |
| Star Private Limited | Health & social care | 2016 |
| Star Supplier Limited | Professional & scientific | 2014 |
| Starplus Features Limited | Information & communication | 2012 |
| Stas-Kam Ltd | Transport & logistics | 2014 |
| Stasboxx Ltd | Transport & logistics | 2025 |
| Stately Corporation Ltd | Professional & scientific | 2021 |
| Status Care Services Ltd | Hospitality | 2022 |
| Stay Apartments Cardiff Limited | Real estate | 2019 |
| Stay Sourcing Ltd | Real estate | 2019 |
| Stay Sweet With Cristina Ltd | Manufacturing | 2023 |
| STC Safeguarding Limited | Professional & scientific | 2023 |
| Steak and Bar Ltd | Hospitality | 2025 |
| Stealth Elite Limited | Wholesale & retail | 2023 |
| Stealth Networx Ltd | Construction | 2022 |
| Steel Building Services Ltd | Administrative & support | 2023 |
| Steel City Engineering Solutions Ltd | Professional & scientific | 2026 |
| Steel Stock Direct Ltd | Wholesale & retail | 2025 |
| Steeping Farms Limited | Agriculture & fishing | 1975 |
| Steer Consulting Ltd | Administrative & support | 2023 |
| Stefaniel Ltd | Transport & logistics | 2025 |
| Stellar Dance Limited | Arts & recreation | 2025 |
| Stema Solution Ltd | Construction | 2019 |
| Stephen Holdings Ltd | Real estate | 2025 |
| Stephens Curry Ltd | Hospitality | 2024 |
| Steps and Stillages Limited | Manufacturing | 2011 |
| Sterling Telecom Solutions Limited | Other services | 2017 |
| Steve Abbott Limited | Construction | 2013 |
| Steve Rutherford Ltd | Other services | 2022 |
| Steven Michael Limited | Construction | 2023 |
| Stevens Court Management Limited | Households | 1989 |
| Stevenson Skin Specialist Limited | Health & social care | 2013 |
| STH Properties Limited | Construction | 2014 |
| Stileman Estates (Northants) Limited | Real estate | 2020 |
| Stokes Carpentry and Joinery Limited | Construction | 2020 |
| Stokes Family Investments Limited | Real estate | 2022 |
| Stone & Webb Limited | Administrative & support | 2013 |
| Stone Bridge Residential's Ltd | Real estate | 2025 |
| Stoneline Elite Construction Ltd | Construction | 2025 |
| Stop N Shop Kettering Ltd | Wholesale & retail | 2024 |
| Stor-Ace Ltd | Transport & logistics | 2025 |
| Store Small Ltd | Transport & logistics | 2021 |
| Storefield Aggregates Limited | Mining & quarrying | 2009 |
| Storefield Environmental Limited | Water & waste | 2011 |
| Storefield Group Limited | Professional & scientific | 2007 |
| Storefield Plant Rushton Limited | Construction | 1995 |
| Stowe Hill Marine Limited | Professional & scientific | 2003 |
| Stph Property Limited | Real estate | 2014 |
| Straight Forward Sales Ltd | Professional & scientific | 2023 |
| Straightforward Advisors Ltd | Professional & scientific | 2020 |
| Strategic Online Services Ltd | Administrative & support | 2008 |
| Stratent Consultancy Ltd | Information & communication | 2024 |