| Skirbeck Gardens Management Company Limited | Households | 2003 |
| Sky Mapper Surveys Ltd | Construction | 2023 |
| Sky Store Ltd | Wholesale & retail | 2025 |
| SKY4PILOTS Limited | Manufacturing | 2019 |
| SL Developments (Nationwide) Limited | Construction | 2019 |
| Slaters Mobile Services Ltd | Administrative & support | 2014 |
| Sleaford Road Management Company Limited | Real estate | 2005 |
| Slightly Shifted Ltd | Information & communication | 2026 |
| SLL Business Consultancy Ltd | Professional & scientific | 2020 |
| Smart Edge House Limited | Real estate | 2025 |
| Smart Move (Boston) Limited | Real estate | 2012 |
| Smart Move Cleaning Limited | Administrative & support | 2017 |
| Smart Move Design & Build Limited | Construction | 2004 |
| Smart Move Hotels (UK) Limited | Hospitality | 2020 |
| Smart Move Hotels Europe Limited | Hospitality | 2017 |
| Smart Move Hotels International Limited | Hospitality | 2026 |
| Smart Move Hotels Limited | Hospitality | 2024 |
| Smart Move Landbank Limited | Real estate | 2021 |
| Smart Start &Pancake Haven Ltd | Manufacturing | 2025 |
| SME Care Ltd | Health & social care | 2024 |
| SMG Development Co Ltd | Construction | 2003 |
| SMG Motors Ltd | Wholesale & retail | 2015 |
| SMI Logistic Ltd | Transport & logistics | 2013 |
| Smith Brickwork and Building Services Ltd | Construction | 2017 |
| Smiths Electrical (Boston) Limited | Construction | 2006 |
| Smiths Property (Lincs) Limited | Real estate | 2021 |
| Smiths Smokery Limited | Manufacturing | 2020 |
| SML Digital Marketing Ltd | Other services | 2025 |
| SML Property Investment Ltd | Real estate | 2026 |
| Smoaks Store Limited | Manufacturing | 2025 |
| Smoke Screen Limited | Extraterritorial | 1993 |
| Smokin Flavour Limited | Hospitality | 2025 |
| SMS Medical Ltd | Health & social care | 2015 |
| Smukss Property Ltd | Real estate | 2025 |
| Sneaker Boys Limited | Wholesale & retail | 2016 |
| Socials by Amber Ltd | Professional & scientific | 2024 |
| Solace Energy Ltd | Manufacturing | 2016 |
| Solca Transport Ltd | Transport & logistics | 2014 |
| Soldout Competitions Ltd | Other services | 2023 |
| Soliaris Ltd | Transport & logistics | 2015 |
| Sololevel Systems Ltd | Information & communication | 2025 |
| Somersby Green Residents Limited | Administrative & support | 1988 |
| Somersby Holdings Ltd | Real estate | 2026 |
| Sonesta Investment Company Limited | Agriculture & fishing | 2015 |
| Sonicride Limited | Households | 1989 |
| Sonkin Cleaning Services Ltd | Administrative & support | 2025 |
| Soteria Solutions Limited | Administrative & support | 2012 |
| Sourcedot Productions Ltd | Wholesale & retail | 2025 |
| South Downs Windscreen Services Limited | Wholesale & retail | 2018 |
| South Lincolnshire Scaffolding Limited | Construction | 1998 |
| South Lincs Glass Shop Limited | Manufacturing | 2004 |
| South Lincs Properties Limited | Real estate | 2012 |
| South Lincs Resin & Paving Limited | Administrative & support | 2025 |
| South Parade Management Company (NO 1) Limited | Real estate | 2012 |
| Southfield Windows & Doors Limited | Construction | 2018 |
| Sovereign Blackwater Ltd | Financial services | 2025 |
| Spalding Fitness Limited | Education | 2017 |
| Spalding Storage Containers Ltd | Transport & logistics | 2024 |
| Spar News Limited | Wholesale & retail | 2011 |
| Sparra Enterprises Ltd | Hospitality | 2019 |
| SPC Developments Limited | Construction | 2006 |
| Specialised Auto & Motorcycle Salvage Limited | Wholesale & retail | 2007 |
| Specialist Recovery Vehicle Hire Limited | Administrative & support | 2002 |
| Speedwell Homes Limited | Real estate | 2005 |
| Spencer-Todd Limited | Other services | 2012 |
| Spices World Boston Limited | Wholesale & retail | 2024 |
| Spirit of Serenity Ltd | Manufacturing | 2021 |
| Sport Facilities Management Limited | Construction | 2020 |
| Sporting Estates Game Ltd | Agriculture & fishing | 2019 |
| Sportsbikeshop Limited | Wholesale & retail | 2005 |
| SRC Homes LET Ltd | Real estate | 2026 |
| Sripal Kumar Ltd | Health & social care | 2014 |
| Ssservises Limited | Construction | 2022 |
| SSV Auto Ltd | Wholesale & retail | 2024 |
| ST Anne's Group (UK) Ltd | Administrative & support | 2006 |
| ST Anns Wharf Management Company Limited | Real estate | 2005 |
| ST George's Preparatory School Limited | Education | 2010 |
| ST Pancras Renewables Ltd | Agriculture & fishing | 2023 |
| ST Peter Close (Lincolnshire) Management Company Limited | Households | 2024 |
| ST Peter's Avenue Pharma Limited | Wholesale & retail | 2024 |
| Stackd Foods Ltd | Hospitality | 2026 |
| Staff U Trust Ltd | Administrative & support | 2021 |
| Staff YOU Like Limited | Administrative & support | 2018 |
| Stainthorpe Limited | Manufacturing | 2024 |
| Stamchem Ltd | Wholesale & retail | 2011 |
| Stamford Garden Centre Limited | Wholesale & retail | 2013 |
| Stamin Trans Ltd | Transport & logistics | 2019 |
| Stan Odell Ltd | Wholesale & retail | 2011 |
| Standartlinc Ltd | Transport & logistics | 2016 |
| Stanfield Darcy Ltd | Real estate | 2020 |
| Staples Electrical Engineering Limited | Construction | 2021 |
| Star Agency Ltd | Administrative & support | 2022 |
| Star Icon Services Ltd | Construction | 2025 |
| Star Taxis Boston Limited | Transport & logistics | 2024 |
| Stark & Daughters Services Ltd | Construction | 2023 |
| Stark Brothers Services Ltd | Wholesale & retail | 2020 |
| Starsys Limited | Professional & scientific | 2003 |
| State Street Bank and Trust Company | | 1993 |
| State Street Bank and Trust Company | | 2023 |
| Staxford Limited | Wholesale & retail | 2004 |