| Sellonix Ltd | Wholesale & retail | 2026 |
| Selworks Ltd | Construction | 2025 |
| Semantic Soft Ltd | Information & communication | 2019 |
| Seml Services Ltd | Administrative & support | 2026 |
| Send for ME UK Ltd | Transport & logistics | 2023 |
| Sentry Retail Ltd | Information & communication | 2026 |
| SER IT Consultants Ltd | Information & communication | 2016 |
| Serc Consultancy Ltd | Professional & scientific | 2016 |
| Sereneveilss Ltd | Wholesale & retail | 2026 |
| Serving Humanity | Agriculture & fishing | 2021 |
| Seven Stars Group Ltd | Financial services | 2023 |
| Seven Starz Ltd | Real estate | 2021 |
| Seweryn Limited | Education | 2025 |
| Sextons of Staines (Haulage & Plant Hire) Limited | | 1975 |
| Seyon Software Solutions Limited | Information & communication | 2012 |
| SF House Ltd | Real estate | 2026 |
| Sgate Housing Limited | Real estate | 2026 |
| Sgtfast Ltd | Transport & logistics | 2025 |
| SH Food & Wine Limited | Wholesale & retail | 2025 |
| SH98 Ltd | Construction | 2025 |
| SHA Innovex Ltd | Administrative & support | 2020 |
| Shabaly Ltd | Professional & scientific | 2025 |
| Shah G Food Palace Limited | Hospitality | 2025 |
| Shah's Cars Group Ltd | Transport & logistics | 2025 |
| Shah's Halal Co Ltd | Hospitality | 2026 |
| Shahid Industries Limited | Professional & scientific | 2014 |
| Shaikh ALI & Co Ltd | Households | 2023 |
| Shaikh Estate Ltd | Real estate | 2025 |
| Shairmusic Limited | Other services | 2017 |
| Shaks Accountancy Ltd | Professional & scientific | 2026 |
| Shakti Technologies Ltd | Information & communication | 2012 |
| Shakxy Cars Ltd | Wholesale & retail | 2019 |
| Shama Puylaurent AHP Associate Limited | Health & social care | 2025 |
| Shamama Ltd | Manufacturing | 2020 |
| Shanaya & Aanaya PVT Ltd | Wholesale & retail | 2023 |
| Shanaya Logistics Ltd | Transport & logistics | 2025 |
| Shangalo Limited | Information & communication | 2015 |
| Share Your Care Limited | Health & social care | 2024 |
| Shareholder Value Limited | Professional & scientific | 2003 |
| Shark Cleaning Services Limited | Administrative & support | 2023 |
| SHAYMY7 Ltd | Construction | 2015 |
| Shazia Merrys Ltd | Real estate | 2026 |
| SHEDSHOP999 Ltd | Wholesale & retail | 2023 |
| Sheen Property Partners Ltd | Real estate | 2025 |
| Sheen Star Ltd | Construction | 2022 |
| Sheen Structures Ltd | Construction | 2025 |
| Shelter International Limited | Construction | 2016 |
| Shepherd and Stone Property Group Limited | Real estate | 2025 |
| Sherides Ltd | Transport & logistics | 2025 |
| Sherock Ltd | Health & social care | 2019 |
| Shhut Limited | Wholesale & retail | 2021 |
| Shifa Box Limited | Administrative & support | 2017 |
| Shine Glazing Limited | Construction | 2019 |
| Shine Pro Cleaning Services Ltd | Administrative & support | 2025 |
| Shinwari Chauffeurs Limited | Transport & logistics | 2016 |
| Ship Fast Global Limited | Other services | 2023 |
| Shipshop Ltd | Wholesale & retail | 2024 |
| Shireya B Ltd | Real estate | 2024 |
| Shiv Cloud Tech Ltd | Information & communication | 2018 |
| Shivashakti Properties Limited | Real estate | 2023 |
| Shiven Limited | Wholesale & retail | 2025 |
| Shivian Ltd | Real estate | 2025 |
| Shoelace Rigging Ltd | Information & communication | 2024 |
| Shoop-Shoop Limited | Wholesale & retail | 2015 |
| Shop TJC Limited | Wholesale & retail | 2005 |
| Shopscafolding Ltd | Professional & scientific | 2016 |
| Shree Shyangdan Properties Ltd | Real estate | 2026 |
| Shri Real Estate Limited | Real estate | 2017 |
| Shruthi Vinoth Kumar Limited | Information & communication | 2012 |
| Shubhauracreation Ltd | Wholesale & retail | 2025 |
| Shutters Repair London Ltd | Manufacturing | 2023 |
| SHY Loyalty Ltd | Hospitality | 2019 |
| Siana 2008 Ltd | Construction | 2015 |
| Siandwils Limited | Information & communication | 2026 |
| Sibal Wholesale Ltd | Wholesale & retail | 2017 |
| Siddam Arts Limited | Information & communication | 2018 |
| Siddam Events Ltd | Hospitality | 2023 |
| Siddam Realtors Limited | Real estate | 2022 |
| Siddique Cars Ltd | Administrative & support | 2025 |
| Sidhu Elite & Construction Ltd | Construction | 2025 |
| Sidhu Fitness Ltd | Arts & recreation | 2022 |
| SIE Services Ltd | Wholesale & retail | 2026 |
| Signs Plus Limited | Professional & scientific | 2004 |
| Signsmiths Ltd | Manufacturing | 2010 |
| Silk Whisper Ltd | Wholesale & retail | 2026 |
| Silky Consultancy Ltd | Professional & scientific | 2020 |
| Silver Key Limited | Construction | 2021 |
| Silver Space Investments Limited | Real estate | 2021 |
| Silverframe Ltd | Transport & logistics | 2025 |
| Silverspoon Services Ltd | Other services | 2019 |
| Silverstone Construction Ltd | Construction | 2025 |
| Sima Fibre Optic Services Ltd | Wholesale & retail | 2025 |
| Simmons & Hawker (AHH) Limited | Real estate | 2022 |
| Simmons & Hawker (Holdings) Limited | Financial services | 2022 |
| Simmons & Hawker (Investments) Limited | Financial services | 2022 |
| Simmons & Hawker (Residential) Limited | Real estate | 2022 |
| Simon Pacer Ltd | Information & communication | 2019 |
| Simplify Systems Ltd | Information & communication | 2021 |
| Simply Building Works Limited | Construction | 2019 |
| Simplycotton Ltd | Wholesale & retail | 2025 |