| Shreyanshs CIC | Education | 2025 |
| Shreyanshs Global Consultancy Ltd | Information & communication | 2025 |
| Shroff Ltd | Wholesale & retail | 2018 |
| Shuresec Consulting Ltd | Information & communication | 2022 |
| Siah Ltd | Wholesale & retail | 2017 |
| Sibiram Consultancy Ltd | Information & communication | 2010 |
| Siddledean Content Limited | Information & communication | 2019 |
| Sidraoptical Ltd | Other services | 2019 |
| Sign and Print Studio Ltd | Professional & scientific | 2006 |
| Signature Designs London Ltd | Professional & scientific | 2023 |
| Silent Gardeners Limited | Extraterritorial | 2022 |
| Silk Designing Ltd | Manufacturing | 2021 |
| Silva Tapas Limited | Hospitality | 2017 |
| Silver Nest Properties Limited | Real estate | 2016 |
| Silver Sevket & Co Accountants Limited | Professional & scientific | 2012 |
| Silver Sevket & Co. Limited | Extraterritorial | 2015 |
| Silver Spring Developments Ltd | Real estate | 2025 |
| Silver Struck Property and Investment Ltd | Real estate | 2020 |
| Silverash Limited | Wholesale & retail | 2025 |
| Silvereef Estates Limited | Real estate | 2007 |
| Silverland Brixton Limited | Construction | 2025 |
| Silverland Investments Ltd | Real estate | 2023 |
| Silverland Residential Ltd | Real estate | 2023 |
| Silvermere Court Caterham Limited | Households | 2006 |
| Silverstream Capital Management Ltd | Real estate | 2024 |
| Sima B & Co Ltd | Professional & scientific | 2024 |
| Simlec Limited | Construction | 2010 |
| Simple Acoustics Limited | Wholesale & retail | 2020 |
| Simple AS a B C Limited | Financial services | 1994 |
| Simple Windows Ltd | Manufacturing | 2023 |
| Simplify Voip Limited | Information & communication | 2015 |
| Simply Care Partners Liability Partnership LLP | | 2013 |
| Simply Casa Limited | Real estate | 2010 |
| Simply Dwellings Limited | Real estate | 2020 |
| Simply Grace Tots Ltd | Manufacturing | 2018 |
| Simply NU Ltd | Other services | 2022 |
| Simply Pathways C.I.C. | Health & social care | 2025 |
| Simply Seamoss LDN Ltd | Hospitality | 2022 |
| Simply Suited Ltd | Wholesale & retail | 2023 |
| Sincere Events Ltd | Other services | 2013 |
| Sindh Consultancy Ltd | Professional & scientific | 2018 |
| Sindh Punjab International Limited | Wholesale & retail | 2016 |
| Sirius Bookkeeping Consultancy Limited | Professional & scientific | 2020 |
| Sirius Decoration Ltd | Construction | 2021 |
| Sisters Food Limited | Hospitality | 2019 |
| Sisu Developer Limited | Real estate | 2019 |
| Sixonmoreton Ltd | Households | 2016 |
| SJR Communications Ltd | Professional & scientific | 2021 |
| SJW Screed Limited | Construction | 2018 |
| SK Plumb Ltd | Construction | 2026 |
| SKA Reality Limited | Financial services | 2025 |
| Skardin Industrial (UK) Limited | Wholesale & retail | 1999 |
| Skeam Limited | Professional & scientific | 2021 |
| Skelt Realty Limited | Real estate | 2024 |
| Sketch Appeal CIC | Education | 2019 |
| Skill Beyond Boundaries Limited | Information & communication | 2018 |
| Skillful Hands CIC | Education | 2026 |
| Skillshive Decentral Ltd | Information & communication | 2023 |
| Skky Properties Limited | Real estate | 2024 |
| SKL Consulting Ltd | Professional & scientific | 2026 |
| Skurf Limited | Wholesale & retail | 2019 |
| SKV Retail Limited | Wholesale & retail | 2023 |
| Skyrise Lift Installations Ltd | Construction | 2022 |
| SL Autos London Ltd | Administrative & support | 2024 |
| SL Woods Ltd | Wholesale & retail | 2026 |
| Slades of Surrey Limited | Health & social care | 2009 |
| SLF Consultancy Services Ltd | Information & communication | 2014 |
| SLF Investments Limited | Financial services | 2021 |
| Slipstream Leadership Development Ltd | Professional & scientific | 2023 |
| Slough Central Property Co Limited | Financial services | 2017 |
| Slurp Games Ltd | Information & communication | 2026 |
| SM Energy Recruitment Limited | Administrative & support | 2025 |
| SM Optics Ltd | Health & social care | 2020 |
| SM Planners Limited | Financial services | 2025 |
| Smallbiz E Solutions Ltd | Information & communication | 2002 |
| Smart Emergency Lighting Ltd | Wholesale & retail | 2024 |
| Smart Media Consulting Limited | Professional & scientific | 2018 |
| Smash Robot Limited | Real estate | 2013 |
| SMF Logistics Ltd | Transport & logistics | 2016 |
| SMG Electrical Services Ltd | Construction | 2012 |
| Smile Design Orthodontics Ltd | Health & social care | 2018 |
| Smiley Building & Construction Ltd | Construction | 2017 |
| Smithz Ltd | Households | 2022 |
| SML Electrical Services Limited | Construction | 2016 |
| Smolin Ltd | Wholesale & retail | 2025 |
| SN Consultancy Limited | Professional & scientific | 2016 |
| SNA Consultants and Maintenance Ltd | Construction | 2026 |
| SNA Print Limited | Manufacturing | 2009 |
| Snacktapgo Ltd | Wholesale & retail | 2026 |
| Snapdog Limited | Information & communication | 2006 |
| Snaps Limited | Information & communication | 2007 |
| SND Grand Ltd | Wholesale & retail | 2025 |
| SNM (UK) Limited | Real estate | 2015 |
| SNP Financial Services Limited | Financial services | 2023 |
| Soba John Driving School Ltd | Education | 2025 |
| Sofia House Dental Care Ltd | Health & social care | 2025 |
| Sohail AMK Limited | Wholesale & retail | 2025 |
| Solarcom Limited | Information & communication | 1997 |
| Solid Franchising Limited | Professional & scientific | 2019 |
| Solvency II Solutions Holdings Ltd | Information & communication | 2023 |