| SAP Property Investment Limited | Real estate | 2013 |
| Sarah Burns Orthodontics & Aesthetics Ltd | Health & social care | 2024 |
| Sarah Swinyard Limited | Administrative & support | 2018 |
| Sarai Hair & Beauty Limited | Other services | 2012 |
| Sareen Portfolio Ltd | Real estate | 2005 |
| Saturday Studios Ltd | Information & communication | 2019 |
| Saval Solutions Limited | Professional & scientific | 2023 |
| SAW IT Loved IT Limited | Wholesale & retail | 2020 |
| Sblended Aquascorp Ltd | Administrative & support | 2016 |
| Sblended Milkshakes Ltd | Wholesale & retail | 2012 |
| Scented Wick Works Limited | Manufacturing | 2024 |
| Scholarco Estates Ltd | Real estate | 2025 |
| Schorem Limited | Real estate | 2022 |
| Sciencia Laboratories Ltd | Professional & scientific | 2019 |
| Score-Ai Ltd | Information & communication | 2026 |
| Scorpio Consultants Ltd | Professional & scientific | 2019 |
| Scotswood Residents' Association Limited | Households | 1992 |
| Scotts Mews Limited | Real estate | 2001 |
| Script to Screen Limited | Administrative & support | 2009 |
| Scrumptious Ltd | Wholesale & retail | 2024 |
| Scutt Consulting Ltd | Professional & scientific | 2025 |
| SDD Metals Limited | Administrative & support | 2011 |
| Sea Crest Productions Limited | Real estate | 2013 |
| Searunner Ltd | Real estate | 2010 |
| Sechi & Sechi Properties Limited | Real estate | 2014 |
| Sechi Skin Clinic Limited | Wholesale & retail | 2020 |
| Second Millennium Limited | Information & communication | 2021 |
| Selman & Sons Ltd | Construction | 2025 |
| Sennossi Limited | Real estate | 2021 |
| Sensortec Solutions Limited | Information & communication | 1998 |
| Sentinel & Bloomington Partners Limited | Financial services | 2025 |
| Serimind Healthcare Ltd | Health & social care | 2023 |
| Serreus Global Technology Limited | Information & communication | 2023 |
| Serviqon Technologies Ltd | Information & communication | 2026 |
| Sevco U1162 | Households | 2000 |
| Seventh Sector Limited | Information & communication | 2014 |
| SG Luxury Developments Ltd | Construction | 2021 |
| SGP Garden Ltd | Wholesale & retail | 2021 |
| Shadowss Limited | Wholesale & retail | 2024 |
| Shalabi Medical Enterprises Ltd | Health & social care | 2024 |
| Shark Fire London Ltd | Construction | 2025 |
| Sharpes Services (Ascot) Ltd | Professional & scientific | 2015 |
| Shed Property Holdings EC Limited | Administrative & support | 2026 |
| Shed Property Holdings HC Limited | Administrative & support | 2026 |
| Shed Property Investments Ltd | Real estate | 2022 |
| Sheehan Site Services Limited | Transport & logistics | 1995 |
| Sheikh Property Investments Ltd | Real estate | 2024 |
| SHER0NE Group Ltd | Information & communication | 2026 |
| Sheridan Grange Management Company Limited | Real estate | 1999 |
| Sherrington Racing Ltd | Arts & recreation | 2024 |
| Sherven Ltd | Professional & scientific | 2017 |
| Shift and Shape Studios Limited | Arts & recreation | 2025 |
| Shika's Brow Bar & Beauty Ltd | Administrative & support | 2020 |
| Shjoe Consulting Ltd | Education | 2016 |
| SHOP4HANDLES Limited | Wholesale & retail | 2007 |
| Shopping for Limited | Professional & scientific | 2018 |
| Shree RAM PS Ltd | Hospitality | 2025 |
| Shrubbs Hill Garden House Limited | Households | 2008 |
| Shrubbs Hill Lane Limited | Administrative & support | 1972 |
| Sieffect Limited | Professional & scientific | 2023 |
| Silicon Squares AI Ltd | Information & communication | 2026 |
| Sillac Associates Limited | Transport & logistics | 2019 |
| Silo Logistics Ltd | Transport & logistics | 2015 |
| Silver Star Auto Refinishing Ltd | Administrative & support | 2017 |
| Silverback Europe Limited | Real estate | 2005 |
| Silvermont Pictures Ltd | Information & communication | 2022 |
| Silverstone Resources Ltd | Wholesale & retail | 2020 |
| Silwood of Ascot DRY Cleaning Limited | Other services | 2017 |
| Silwood Technology Ltd | Information & communication | 1991 |
| Simon Pearce Limited | Information & communication | 2015 |
| SIMPLICITY37 Ltd | Information & communication | 2015 |
| Simply Limited | Wholesale & retail | 2001 |
| Sintercast Limited | Manufacturing | 1986 |
| Siphr Impact Ltd | Energy | 2024 |
| Sisaan Construction Ltd | Construction | 2026 |
| Sisaan Properties Ltd | Real estate | 2024 |
| SIX Dots Design Limited | Manufacturing | 2021 |
| Sixpenny Woodside Limited | Administrative & support | 2026 |
| Sizigi Ltd | Information & communication | 2022 |
| SJ Estate Developments Limited | Real estate | 2026 |
| SK Residential Properties Limited | Households | 2021 |
| Sk&Sh Medical Ltd | Health & social care | 2019 |
| Skcustoms Ltd | Construction | 2022 |
| SKG Acquisitions Limited | Administrative & support | 2021 |
| Skinirvana Limited | Manufacturing | 2017 |
| Skinlaze Ltd | Education | 2025 |
| Skinvie UK Limited | Other services | 2021 |
| Sklinic Ltd | Other services | 2025 |
| SKS 1 SUB Limited | Real estate | 2023 |
| SL5 Ventures Limited | Real estate | 2025 |
| Sleep School Health Ltd | Health & social care | 2023 |
| Sloan Property Group Ltd | Real estate | 2019 |
| Sloanindustries Limited | Other services | 2010 |
| Smart FT Property Investments Ltd | Real estate | 2025 |
| Smile Studio Spaces Ltd | Wholesale & retail | 2024 |
| SMILE4ME Limited | Health & social care | 2020 |
| Smink Limited | Manufacturing | 2008 |
| Smith's of Covent Garden Ltd. | Real estate | 1963 |
| Snowmec Limited | Extraterritorial | 2010 |
| Snug Nursery Schools Limited | Education | 2013 |