| Scrutton Street Studios Limited | Information & communication | 2016 |
| Scyld Capital LLP | | 2024 |
| Scyld Management Limited | Professional & scientific | 2024 |
| SD Collective Ltd | Wholesale & retail | 2020 |
| SDL Property Management Ltd | Real estate | 2024 |
| SDV Electrical Contractors Ltd | Construction | 2015 |
| SEB Ltd | Extraterritorial | 2009 |
| Sebpo Ltd | Administrative & support | 2018 |
| Second Site Sailing Limited | Hospitality | 1991 |
| Select Interiors Limited | Construction | 1994 |
| Semitechnology Ltd | Manufacturing | 2011 |
| Sempiternum Ltd | Professional & scientific | 2018 |
| Sensory Design & Technology Ltd | Professional & scientific | 2004 |
| Serene Mint Ltd | Professional & scientific | 2024 |
| Serenity Hair Lounge Ltd | Other services | 2019 |
| Serenity Valley Holdings Ltd | Real estate | 2022 |
| Serious Admin Services Ltd | Administrative & support | 2001 |
| Seventy Four Limited | Administrative & support | 2013 |
| SEW Susie Limited | Wholesale & retail | 2026 |
| SFG Property Management Limited | Households | 2020 |
| SG Autovest LLP | | 2023 |
| SG Ltd | Extraterritorial | 2008 |
| SGA Technologies Limited | Manufacturing | 1969 |
| Shalini Sharma Ltd | Health & social care | 2021 |
| Shanyai World Limited | Information & communication | 2019 |
| Sharp Built Homes Ltd | Construction | 2021 |
| Shawyer Woodcraft & Co Ltd | Manufacturing | 2026 |
| Shepherd Filters UK Ltd | Other services | 2022 |
| Shimpac Limited | Extraterritorial | 1999 |
| Shinboku Ltd | Real estate | 2024 |
| Shire Hill Holdings Limited | Financial services | 2020 |
| Shivlathyrus Investments Limited Liability Partnership | | 2009 |
| Shivlathyrus Services Limited | Professional & scientific | 2025 |
| SHP Property Developments Ltd | Real estate | 2017 |
| Shpdr Ltd | Wholesale & retail | 2021 |
| Shutterbrand Limited | Professional & scientific | 2025 |
| SHY Bambino Ltd | Education | 2023 |
| Shyguy Art Limited | Arts & recreation | 2018 |
| Sibbards Investments Limited | Construction | 2017 |
| Sibbards Property Management Limited | Real estate | 2019 |
| Sightmead Limited | Agriculture & fishing | 1979 |
| Sigma Management Holdings Ltd | Real estate | 2022 |
| Signagelive Limited | Information & communication | 2000 |
| Silver Lantern Limited | Wholesale & retail | 2011 |
| Silver Squirrel Ltd. | Wholesale & retail | 2018 |
| Silver Street Barbers Ltd | Other services | 2019 |
| Silver Tree Contracting Limited | Administrative & support | 2020 |
| Silverbale Limited | Professional & scientific | 1985 |
| Silverwood Architecture and Building Services Ltd | Construction | 2012 |
| Simon Evans Hairdressing Limited | Other services | 2007 |
| Simon Sheldon Consulting Limited | Administrative & support | 2019 |
| Simpkins Farm Limited | Real estate | 2017 |
| Simply ABS Consulting Limited | Professional & scientific | 2023 |
| Sinclair James Group Limited | Administrative & support | 2026 |
| Sinnott Acquisitions Ltd | Information & communication | 2025 |
| Sinus UK - Patient Organisation CIC | Health & social care | 2021 |
| Sion HR Ltd | Administrative & support | 2021 |
| Sitegrafters Ltd | Administrative & support | 2023 |
| Skai Boutique Limited | Wholesale & retail | 2024 |
| SKI Expectations Limited | Professional & scientific | 2009 |
| Skialight Limited | Wholesale & retail | 2015 |
| Skills Framework Partners (SFP) Ltd | Professional & scientific | 2011 |
| Skintight Media Ltd | Extraterritorial | 2014 |
| Skylogic Aero Ltd | Professional & scientific | 2025 |
| Skytex Logistics Limited | Wholesale & retail | 2026 |
| Skyward Lofts Limited | Manufacturing | 2026 |
| Slam Fit Limited | Arts & recreation | 2022 |
| SM Walker Ltd | Professional & scientific | 2023 |
| Small Human, Big Dreams Limited | Extraterritorial | 2018 |
| Smart Finds Ltd | Wholesale & retail | 2019 |
| Smart Money Data Ltd | Other services | 2026 |
| Smart Money Dealing Ltd | Other services | 2022 |
| Smart Surveyors Limited | Construction | 2005 |
| Smart TEC Property Maintenance Limited | Construction | 2021 |
| Smartbrief Broadcast App Limited | Information & communication | 2018 |
| Smartnet Publishers Ltd | Information & communication | 2016 |
| Smartphone Media Group Limited | Information & communication | 2017 |
| Smashandgrabfoodtruck Ltd | Hospitality | 2025 |
| Smeserv Limited | Energy | 2012 |
| Smith Sumner Design Partnership Limited | Professional & scientific | 1997 |
| Smokin' Roses Vintage LLP | | 2025 |
| Smother Spudder's Ltd | Hospitality | 2024 |
| So-Vida Ltd | Administrative & support | 2017 |
| Solarbarn Generation Limited | Energy | 2011 |
| Solarbarn Limited | Construction | 2010 |
| Solid Spikes Limited | Manufacturing | 2006 |
| SOLO2DARWIN Ltd | Transport & logistics | 2019 |
| Soni PMC Limited | Extraterritorial | 2013 |
| Soni Properties UK Ltd | Real estate | 1999 |
| Sonic Chanter Ltd | Information & communication | 2023 |
| Sonic Data Limited | Information & communication | 2013 |
| Sonicai Limited | Information & communication | 2025 |
| Sophie Freeman Events Limited | Professional & scientific | 2018 |
| Soul Nest Retreats Limited | Health & social care | 2025 |
| Source Business Services Limited | Professional & scientific | 2013 |
| South Coast SLT Ltd | Information & communication | 2018 |
| Southfield Ickleton Management Limited | Professional & scientific | 1997 |
| SP Education Services Limited | Education | 2024 |
| Spark Economics Ltd | Other services | 2024 |
| Sparrows END Farm Shop Limited | Wholesale & retail | 2020 |