| Soul Sister Swim Ltd | Wholesale & retail | 2024 |
| Sounds Heavenly Limited | Manufacturing | 2008 |
| Sounds Natural Ltd | Extraterritorial | 2016 |
| South London Psychology Ltd | Health & social care | 2022 |
| Soyfoods Limited | Manufacturing | 1983 |
| Sozgow Limited | Financial services | 2025 |
| Space Foods Limited | Agriculture & fishing | 1962 |
| Sparkly Clean by Monika Limited | Administrative & support | 2024 |
| Sparky Labs Limited | Wholesale & retail | 2016 |
| Specialised Valve Solutions Limited | Professional & scientific | 2012 |
| Spectrum House Ltd | Financial services | 2006 |
| Spectrum Software Solutions Limited | Information & communication | 2020 |
| Spence Arnold Ltd | Information & communication | 2014 |
| Spencer and Wilcox Ltd | Construction | 2019 |
| Spencer Property Solutions Limited | Construction | 2014 |
| Spencer Residential Holdings Limited | Real estate | 2026 |
| Spirit Level Success Ltd | Other services | 2016 |
| Sportivomedia Limited | Information & communication | 2008 |
| Sports Facilities Group Limited | Administrative & support | 2005 |
| Sportsground Maintenance & Machinery Limited | Manufacturing | 2003 |
| Spot on Sport Ltd | Wholesale & retail | 2023 |
| Spray Kitchen Elite Ltd | Construction | 2020 |
| Spring Chicken Games Ltd | Manufacturing | 2026 |
| Spring Lane Holdings Ltd | Financial services | 2024 |
| Springfield Green Limited | Real estate | 2014 |
| Springfield Partnership Limited | Wholesale & retail | 2023 |
| Springfield Stud Ltd | Agriculture & fishing | 2019 |
| Springwood Management Services Limited | Professional & scientific | 2005 |
| Sprocketcog Ltd | Manufacturing | 2013 |
| SPT Associates (EM) Ltd | Construction | 2022 |
| Spudlicious Ltd | Hospitality | 2022 |
| Squeaky Klin Limited | Administrative & support | 2025 |
| Squirrel Stores Limited | Wholesale & retail | 2018 |
| SR Integrated Engineering Ltd | Professional & scientific | 2025 |
| SR Specialty Ltd | Financial services | 2023 |
| SRB Associates (Leicestershire) Limited | Professional & scientific | 2013 |
| Srisupa Thai Massage Wellness & Spa Ltd | Other services | 2026 |
| SSE Lettings Ltd | Real estate | 2025 |
| ST. Mary's (Market Harborough) Limited | Households | 2003 |
| Stace Roofing Limited | Construction | 2010 |
| Stacey the Rainmaker Limited | Professional & scientific | 2022 |
| Standone LLP | | 2014 |
| Stanton Asset Management Limited | Real estate | 2011 |
| Stapleford Doggy Day Care Limited | Other services | 2023 |
| Stapleford Estate Events Limited | Other services | 2023 |
| Starlight Union Property Limited | Real estate | 2021 |
| Stateley Developments Limited | Hospitality | 2016 |
| Station View Property Ltd | Construction | 2020 |
| Station View Residents Management Company Limited | Households | 2020 |
| Staveley Gardens Development Company Limited | Construction | 2019 |
| Staveley Lodge Development Company Limited | Construction | 2019 |
| Steam & Bean Coffee Ltd | Hospitality | 2026 |
| Steamspa Ltd | Professional & scientific | 2022 |
| Steelwork by Sheridans Ltd | Construction | 2024 |
| Stem Consults LLP | | 2024 |
| Steve Ellerby HR Limited | Administrative & support | 2007 |
| Steve Mound Fencing Limited | Construction | 2019 |
| Steven Lewis Ltd | Financial services | 2025 |
| Steve’S Motoring Solutions (SMS) Limited | Education | 2025 |
| Stewart Halford Sales Limited | Wholesale & retail | 2018 |
| Stone Lion Services Ltd | Administrative & support | 2013 |
| Stonecroft Builders Limited | Construction | 2019 |
| Stonecroft Country Homes Limited | Construction | 2000 |
| Stonelodge Farm Limited | Agriculture & fishing | 2020 |
| Storage Answers Limited | Administrative & support | 2020 |
| Storage Concepts Limited | Construction | 1984 |
| Storage Optimal Limited | Administrative & support | 2020 |
| Storage Resolutions Limited | Administrative & support | 2020 |
| Storage Solved Limited | Administrative & support | 2020 |
| Storehouse Facilities Limited | Manufacturing | 2020 |
| Storehouse Solutions Limited | Manufacturing | 2020 |
| Storrax Shopfitters Limited | Construction | 2013 |
| Strawberry Court Management Co. Limited | Households | 1994 |
| Strongvan Ltd | Transport & logistics | 2024 |
| Stuart's Outdoor Cleaning Ltd | Administrative & support | 2023 |
| Students International Limited | Hospitality | 1994 |
| Studio Forma Pilates Ltd | Arts & recreation | 2025 |
| Studio Pro 17 Ltd | Other services | 2026 |
| Studio Softbox Limited | Information & communication | 2018 |
| Style Bureau Ltd | Other services | 2026 |
| Sudel Property Limited | Real estate | 2026 |
| SUE Tilley Associates Limited | Professional & scientific | 2024 |
| Sulney Nursery Ltd | Administrative & support | 2022 |
| SUM Thing Good Limited | Real estate | 2021 |
| Sundown 247 Limited | Wholesale & retail | 2015 |
| Sunnier Skies Care Services Ltd | Health & social care | 2020 |
| Sunny Skies Enterprise CIC | Health & social care | 2019 |
| Sunnymead Sports Group Ltd | Wholesale & retail | 2026 |
| Sunz IT Solutions Ltd | Information & communication | 2020 |
| Superior Property Maintenance & Improvements Ltd | Administrative & support | 2014 |
| Superscada Ltd | Manufacturing | 2023 |
| Supply Personnel Limited | Administrative & support | 2019 |
| Support Stack Limited | Information & communication | 2015 |
| Surplus Sales Limited | Professional & scientific | 2001 |
| Swan Lodge Limited | Agriculture & fishing | 1994 |
| Swasti Group Limited | Professional & scientific | 2020 |
| Sweetpot Ltd | Financial services | 2010 |
| SWI Security Concepts Limited | Construction | 2017 |
| Swithland Systems LLP | | 2005 |
| Sycamore Energy Assessors Ltd | Other services | 2007 |