| SAM Decorating Ltd | Construction | 2024 |
| SAM Pesterfield Builders Limited | Construction | 2002 |
| Same Shop Ltd | Wholesale & retail | 2024 |
| Samkev Medical Limited | Health & social care | 2025 |
| Samual Vickers Ltd | Other services | 2023 |
| Sanderson Group Holdings Limited | Financial services | 2018 |
| Sandford Consulting Limited | Professional & scientific | 2015 |
| Sandford Properties (Boston) Ltd | Real estate | 2021 |
| Sandip and Sons Property Services Limited | Real estate | 2017 |
| Sandra Snell Physiotherapy Ltd | Health & social care | 2011 |
| Sanov Express Ltd | Transport & logistics | 2021 |
| Santos Consulting Group Ltd | Information & communication | 2026 |
| Sapphire Digital Health Advisory Ltd | Information & communication | 2026 |
| Sapphire Joani Limited | Wholesale & retail | 2024 |
| Sarah & Care Limited | Administrative & support | 2019 |
| Sarah J Mckay Limited | Professional & scientific | 2011 |
| Saturn Bars Limited | Transport & logistics | 2025 |
| Saules Auto Ltd | Wholesale & retail | 2024 |
| Saulius Cargo Limited | Transport & logistics | 2024 |
| Savas Transport Ltd | Transport & logistics | 2025 |
| Save Time in Business Ltd | Information & communication | 2024 |
| SAY YES Therapy Ltd | Health & social care | 2023 |
| SB Housing Limited | Real estate | 2021 |
| SBS Engineering Inspection Services Ltd | Professional & scientific | 2015 |
| Scadanet Limited | Information & communication | 2009 |
| Scanner Services Ltd | Manufacturing | 1996 |
| SCM Properties Limited | Real estate | 2015 |
| Scoffit Limited | Hospitality | 2026 |
| Scott LEE Bartlett Ltd | Construction | 2012 |
| Scotts Industries Limited | Manufacturing | 2003 |
| Scotts Precision Manufacturing Limited | Manufacturing | 2008 |
| Sd&M Real Estate Holdings Ltd | Real estate | 2023 |
| Sdipcharge Ltd | Financial services | 2021 |
| SDW Brickwork Ltd | Construction | 2026 |
| Sebtec Limited | Wholesale & retail | 2025 |
| Secure FOG Limited | Manufacturing | 2021 |
| Sekyd Property Services Ltd | Construction | 2024 |
| SELLFOR444 Limited | Other services | 2026 |
| Setal Ltd | Wholesale & retail | 2019 |
| Setra Wood Products Limited | Wholesale & retail | 1998 |
| Seventh Heaven Cafe Limited | Hospitality | 2010 |
| Seyhan Meal Ltd | Hospitality | 2024 |
| SG Property Management Services Limited | Real estate | 2017 |
| SGB Innovations Ltd | Financial services | 2024 |
| SGMECHANICAL24 Limited | Manufacturing | 2026 |
| SGS Boilers Limited | Construction | 2026 |
| Shalom First Company Limited | Real estate | 2019 |
| Shane Stengel Construction Limited | Construction | 2005 |
| Shapla Lincs Ltd | Hospitality | 2020 |
| Shark Wash and Shine Ltd | Administrative & support | 2024 |
| Sharman Burgess Lettings Limited | Extraterritorial | 2016 |
| Sharman Burgess Properties Limited | Real estate | 2000 |
| Sharpe Move Ltd | Real estate | 2020 |
| Sheltered Spaces Ltd | Construction | 2019 |
| Shephards (Bakers) Limited | Manufacturing | 1946 |
| Sherridan Homes Limited | Construction | 2018 |
| Sherwood Forest Brewing Company Limited | Manufacturing | 2008 |
| SHG Tree House Ltd | Real estate | 2024 |
| Shhs Consultancy Limited | Extraterritorial | 2011 |
| Shields Wilson Limited | Professional & scientific | 2020 |
| Shins Cleaning and Maintenance Ltd | Construction | 2018 |
| Shop by DS Limited | Wholesale & retail | 2025 |
| SIB Medical Ltd | Health & social care | 2015 |
| Sibili Group Live & Retail Ltd | Wholesale & retail | 2023 |
| Sibling Keys Property Rentals Ltd | Real estate | 2026 |
| Sibsey Energy Management Limited | Energy | 2024 |
| Sibsey Power Generation Limited | Energy | 2024 |
| Sibsey Stores Ltd | Wholesale & retail | 2025 |
| Sidlauskas Trans Ltd | Transport & logistics | 2025 |
| Silk Accommodation Ltd | Health & social care | 2025 |
| Silt Side Service Limited | Wholesale & retail | 1983 |
| Silver Squid Jewellery Ltd | Manufacturing | 2023 |
| Silverdale Avenue Management Limited | Administrative & support | 2016 |
| Silvester Homes Ltd | Construction | 2020 |
| Simon Cooper Property Limited | Real estate | 2023 |
| Simon Foster Farm Services Limited | Administrative & support | 2006 |
| Simon Middlebrook Farriers Ltd | Agriculture & fishing | 2009 |
| Simpatico Services Ltd | Construction | 2020 |
| Simple Accountancy Ltd | Professional & scientific | 2022 |
| Simple Tenant Find Ltd | Hospitality | 2021 |
| Simplybest Ltd | Wholesale & retail | 2021 |
| Sinthaweekoon Ltd | Other services | 2024 |
| Sirevoc Ltd | Hospitality | 2023 |
| Sirius Supplier Ltd | Transport & logistics | 2022 |
| Siuntos Kroviniai Ltd | Transport & logistics | 2020 |
| SJ Property Solutions Group Ltd | Construction | 2025 |
| SJC LM Lincolnshire Limited | Hospitality | 2026 |
| SJC LM Mansfield Limited | Hospitality | 2023 |
| SJG Electrical and Security Limited | Construction | 2009 |
| SJH Boston Limited | Real estate | 2015 |
| SJP Locksmiths and Property Maintenance Ltd | Administrative & support | 2016 |
| SK Capital Global Investments Bullion Reserve Limited | Financial services | 2026 |
| SK Capital Global Investments Ltd | Financial services | 2025 |
| SK Elite Solicitors Ltd | Professional & scientific | 2026 |
| Skegness Blinds & Interiors Ltd | Wholesale & retail | 2025 |
| Skew Whiff Design Limited | Professional & scientific | 2005 |
| Skin Solutions Aesthetic Clinic Ltd | Other services | 2023 |
| Skinbyevangeline Ltd | Other services | 2025 |
| Skinners Ice Cream Limited | Manufacturing | 2014 |
| Skinsmar Ltd | Information & communication | 2026 |