| Skyward Select Recruitment Solutions Ltd | Administrative & support | 2026 |
| Slavsons Ltd | Wholesale & retail | 2018 |
| Slaybaugh Enterprises Ltd | Arts & recreation | 2025 |
| SLC Management Consultancy Limited | Professional & scientific | 2013 |
| Sllatine Logistics Ltd | Transport & logistics | 2025 |
| SM2COMMUNICATE Limited | Professional & scientific | 2012 |
| SMA Property Investment Ltd | Real estate | 2020 |
| Small Gains Limited | Administrative & support | 2020 |
| Smamci Ltd | Wholesale & retail | 2023 |
| Smart Buy Store Ltd | Wholesale & retail | 2026 |
| Smart Hive Ltd | Construction | 2019 |
| Smart Prime Ltd | Wholesale & retail | 2023 |
| Smart Spaces Construction Ltd | Construction | 2024 |
| Smart Sparkies Limited | Construction | 2016 |
| Smartfix U.K. Limited | Wholesale & retail | 2001 |
| Smarty Schoolwear Ltd | Wholesale & retail | 2014 |
| Smig UK Limited | Transport & logistics | 2017 |
| Smilewood Limited | Professional & scientific | 2002 |
| Smith & Webb (Drilling) Limited | Construction | 1977 |
| Smma Properties Ltd | Real estate | 2019 |
| SMS Designs Limited | Construction | 2010 |
| SN Technology Group Limited | Information & communication | 2025 |
| SNL James Limited | Real estate | 2015 |
| Snowgold Developments (Hertfordshire) Limited | Real estate | 2013 |
| Snowgold Developments (Woodside) Limited | Construction | 2001 |
| Snowgold Developments Grimsby Ltd | Real estate | 2015 |
| Snowgold Developments Limited | Construction | 1997 |
| Snowgold Leisure Limited | Hospitality | 1996 |
| Soccer Services Limited | Arts & recreation | 1979 |
| Softbyt Limited | Information & communication | 2023 |
| Sogo Mobility Limited | Administrative & support | 2020 |
| Solanke Jewellery Ltd | Wholesale & retail | 2020 |
| Solescope Studio & Design Ltd | Information & communication | 2026 |
| Solihull Racquets & Healthtrack Limited | Professional & scientific | 1995 |
| Solin Driving School Limited | Education | 2024 |
| Solo Air Services Ltd | Transport & logistics | 2019 |
| Solo Services Limited | Transport & logistics | 2023 |
| Solocare 2016 Unlimited | Administrative & support | 2016 |
| Solyd Ltd | Administrative & support | 2023 |
| Somerstone Investments Limited | Real estate | 2014 |
| Somervile Consulting Limited | Information & communication | 2019 |
| Something Necessary Ltd | Wholesale & retail | 2022 |
| Sonocouture Ltd | Wholesale & retail | 2024 |
| Sonograde Limited | Health & social care | 2023 |
| Sonya's Beauty Ltd | Other services | 2021 |
| Soros Transport and Removals Limited | Transport & logistics | 2014 |
| Soryn Builders Ltd | Construction | 2023 |
| Soulkonnection Limited | Information & communication | 2024 |
| Sounds Mint Ltd | Information & communication | 2024 |
| Sour Firm Ltd | Wholesale & retail | 2019 |
| Sourcedbysolanke Ltd | Wholesale & retail | 2020 |
| South Herts Financial Services Ltd | Financial services | 2014 |
| South Herts Properties Limited | Real estate | 2003 |
| South Mimms Properties Limited | Financial services | 2023 |
| SP Secure Ltd | Administrative & support | 2026 |
| SPA4CARS Ltd | Other services | 2023 |
| Space Systems & Partners for Exploration Ltd | Information & communication | 2024 |
| Sparkle N Shine Cleaning Limited | Administrative & support | 2018 |
| Sparkle Supported Living Ltd | Health & social care | 2021 |
| Sparkle-Shine-Cleaning Ltd | Administrative & support | 2025 |
| Sparklenest Cleaning Services Ltd | Administrative & support | 2025 |
| Sparklenestclothing Ltd | Wholesale & retail | 2026 |
| Special Catering and Decoration Ltd | Hospitality | 2023 |
| Special Experience Ltd | Arts & recreation | 2020 |
| SPG Tropical Foods Limited | Wholesale & retail | 2000 |
| Spicefield (Herts) Ltd | Hospitality | 2017 |
| Spicers Carpets and Beds Limited | Wholesale & retail | 2005 |
| Spicypot Limited | Hospitality | 2026 |
| Spinel Studios Ltd | Manufacturing | 2025 |
| Spinox Limited | Other services | 2025 |
| Spis Tech Ltd | Information & communication | 2009 |
| Splash-Cfd Ltd | Information & communication | 2026 |
| Sponono Care Ltd | Health & social care | 2019 |
| Sports NOW Social Leagues Ltd | Arts & recreation | 2024 |
| Spotlis Cleaning Limited | Administrative & support | 2025 |
| Springskill Ltd | Wholesale & retail | 2022 |
| Springstead Village Cherry Hinton Residents Management Company Limited | Households | 2024 |
| Sprint-Uk Ltd | Transport & logistics | 2021 |
| Squires Property MK Limited | Real estate | 2022 |
| SR Solutions London Ltd | Construction | 2023 |
| SRI Annapoorna Restaurants Ltd | Hospitality | 2026 |
| SRI Consultants Limited | Professional & scientific | 2000 |
| Srpm Consulting Limited | Professional & scientific | 2014 |
| SRR Consult Limited | Professional & scientific | 2017 |
| SS Diaconu Ltd | Transport & logistics | 2016 |
| SS99 Design Limited | Other services | 2019 |
| Ssap Solutions Limited | Information & communication | 2019 |
| SSB Erad Limited | Administrative & support | 2015 |
| SSB Trade Ltd | Professional & scientific | 2024 |
| ST Albans Basement Limited | Construction | 2014 |
| ST Albans Steiner Kindergarten Limited | Education | 2002 |
| ST George's Mews Property Management Limited | Households | 2000 |
| ST Metals Ltd | Transport & logistics | 2024 |
| ST Plumbing & Heating Solutions Ltd | Construction | 2025 |
| ST. Andrews Management Company (Stamford Hill) Limited | Households | 1999 |
| Stac Consulting Limited | Professional & scientific | 2021 |
| Stag Electrical Limited | Manufacturing | 2003 |
| Stag House Hertford Limited | Households | 2023 |
| Stag Publications Holdings Limited | Professional & scientific | 2014 |
| Stallon Ltd | Construction | 2020 |