| Segs Enterprise Ltd | Wholesale & retail | 2012 |
| Seifton Transport Limited | Transport & logistics | 2025 |
| Select Residential Lettings Limited | Real estate | 2002 |
| Sellwood Developments Limited | Real estate | 2018 |
| Sensei Training and Consultancy Service Limited | Health & social care | 2011 |
| Sentinel Intelligence Ltd | Administrative & support | 2024 |
| Serea Limited | Administrative & support | 2018 |
| Servd Limited | Information & communication | 2011 |
| Seth Bradford Property Ltd | Construction | 2023 |
| Shamaila Ings Limited | Health & social care | 2017 |
| SHD Composite Materials (USA) Ltd | Manufacturing | 2018 |
| SHD Composite Materials Ltd | Manufacturing | 2009 |
| SHD Engineering Limited | Manufacturing | 2016 |
| SHD Holdings Limited | Manufacturing | 2016 |
| Shearman Keylock Limited | Extraterritorial | 2010 |
| Sheldrake Security Consultancy Ltd | Information & communication | 2020 |
| Shire Hire Ltd | Administrative & support | 2019 |
| Shirong Ltd | Hospitality | 2026 |
| SI Smith Co Ltd | Information & communication | 2021 |
| SI the Spud Limited | Financial services | 2023 |
| Sibley Plumbing and GAS Ltd | Construction | 2023 |
| Sids Group Ltd | Real estate | 2024 |
| Silverlinc Developments Ltd | Construction | 2018 |
| Silverwood Asset Management Ltd | Financial services | 2019 |
| Simon Smith Construction Ltd | Construction | 2017 |
| Simple Landscaping Solutions Ltd | Administrative & support | 2025 |
| Sitesol Ltd | Professional & scientific | 2026 |
| Skate Civils Limited | Construction | 2024 |
| Slea and Moss Ltd | Professional & scientific | 2016 |
| Slea Riverbank Trust Ltd | Real estate | 2022 |
| Sleaford Automation Limited | Wholesale & retail | 2009 |
| Sleaford Automotive Services Ltd | Wholesale & retail | 2018 |
| Sleaford Barber Limited | Other services | 2024 |
| Sleaford Building Holdings Limited | Construction | 2014 |
| Sleaford Building Services Limited | Construction | 2003 |
| Sleaford Commercials Limited | Wholesale & retail | 2025 |
| Sleaford Corn Exchange Limited | Construction | 2012 |
| Sleaford Day Nursery Holdings Ltd | Education | 2022 |
| Sleaford Farming Company | Agriculture & fishing | 1951 |
| Sleaford Food Group Limited | Professional & scientific | 2004 |
| Sleaford Gallery Arts Trust Limited | Arts & recreation | 2008 |
| Sleaford Glass and Glazing Limited | Construction | 2020 |
| Sleaford HCW Ltd | Other services | 2014 |
| Sleaford HGV Services Ltd | Wholesale & retail | 2018 |
| Sleaford Hvac Ltd | Construction | 2022 |
| Sleaford in Bloom Ltd | Administrative & support | 2001 |
| Sleaford Masonic Buildings Company Limited(The) | Administrative & support | 1916 |
| Sleaford Play Town Limited | Wholesale & retail | 2019 |
| Sleaford Quality Foods Limited | Manufacturing | 1968 |
| Sleaford Stoves Ltd | Construction | 2025 |
| Sleaford Taxi Company Limited | Transport & logistics | 1964 |
| Sleaford Trading Company Limited | Professional & scientific | 1995 |
| Sleafordian Coaches Limited | Transport & logistics | 2013 |
| Sleafordian Limited | Transport & logistics | 2021 |
| SM Build & Renovate Ltd | Construction | 2025 |
| SMG Healthcare Limited | Health & social care | 2007 |
| SMH Transport Lincolnshire Ltd | Transport & logistics | 2020 |
| SMH Tyres Limited | Wholesale & retail | 2009 |
| SMH Wealth Associates Ltd | Financial services | 2020 |
| Smith Agri Contract Ltd | Agriculture & fishing | 2022 |
| Smith Construction (Heckington) Limited | Construction | 1992 |
| SMS Solutions Ltd | Information & communication | 2011 |
| Softekk Limited | Information & communication | 2018 |
| Solaceera Ltd | Wholesale & retail | 2025 |
| Soma Cafe Ltd | Hospitality | 2025 |
| Sooth Ltd | Manufacturing | 2025 |
| SOS Fuels Limited | Wholesale & retail | 2018 |
| Sotto Voce Limited | Information & communication | 2013 |
| Sotto Voce Music Publishing Limited | Information & communication | 2013 |
| Souths Farming Limited | Administrative & support | 2008 |
| Souths Properties (Lincs) Limited | Real estate | 2019 |
| Spa Developments Limited | Construction | 2014 |
| Spanby Ltd | Information & communication | 2024 |
| Spark Talent Ltd | Administrative & support | 2025 |
| Specialist Education Training Services Ltd | Education | 2023 |
| Spectrum Management (Rochester) Limited | Real estate | 1986 |
| Speedway Car Wash Ltd | Administrative & support | 2020 |
| Speedway Corner Garage Ltd | Wholesale & retail | 2018 |
| Spice Court Ltd | Hospitality | 2021 |
| Spire View Maintenance Limited | Other services | 2018 |
| Spiritline Bookkeeping Services Ltd | Professional & scientific | 2025 |
| Spolton Ltd | Financial services | 2017 |
| Spowage Promotions Limited | Wholesale & retail | 2022 |
| Spraytrac Limited | Agriculture & fishing | 1982 |
| Springthorpe Construction Limited | Construction | 2012 |
| ST Bookkeeping Services Limited | Professional & scientific | 2010 |
| ST George's Academy Trust | Education | 2009 |
| Stacey Addison Limited | Agriculture & fishing | 2018 |
| Stacks Funhouse Ltd | Arts & recreation | 2020 |
| Stamford HR & People Consulting Ltd | Administrative & support | 2026 |
| Star Mobile Sleaford Ltd | Wholesale & retail | 2025 |
| Starbuck & Associates Limited | Professional & scientific | 2020 |
| Stark MED Limited | Health & social care | 2024 |
| Starlight Quantum Computers Ltd | Professional & scientific | 2025 |
| Starlincs Auriga Ltd. | Professional & scientific | 2001 |
| Starlite Dance Holdings Ltd | Professional & scientific | 2021 |
| Starlite Direct Limited | Wholesale & retail | 2005 |
| Stationside Cabins Ltd | Construction | 2021 |
| Stay at Watergate Ltd | Hospitality | 2018 |
| Steve Lawson Plumbing Limited | Construction | 2014 |