| Seize Your Moments Smart Bath Tubs Ltd | Professional & scientific | 2025 |
| Selly Park Ltd | Real estate | 2018 |
| Semhelp Ltd | Information & communication | 2021 |
| Sendowa Limited | Transport & logistics | 2025 |
| Sense Massage Therapy Ltd | Health & social care | 2014 |
| Sentinel Door Supervision Limited T/A Sentinel Security Services Ltd | Administrative & support | 2017 |
| Senwick Road Motors Garage Limited | Wholesale & retail | 2025 |
| SEO Moves Ltd | Information & communication | 2015 |
| Seooyh Ltd | Extraterritorial | 2025 |
| Seraphic Records Limited | Information & communication | 2024 |
| Serban Homes Ltd | Financial services | 2025 |
| Serenco (UK) Limited | Wholesale & retail | 1999 |
| Serene Events Limited | Other services | 2018 |
| Serene Haven Solutions Ltd | Health & social care | 2024 |
| Serrago Ltd | Manufacturing | 2020 |
| Servanta Services Ltd | Hospitality | 2026 |
| Service Logistics Ltd | Administrative & support | 2009 |
| Service SIX | Other services | 2008 |
| Serviced Places Ltd | Hospitality | 2023 |
| Servswift Holdings Ltd | Financial services | 2023 |
| Servswift Limited | Manufacturing | 2020 |
| Servswiftfm Limited | Construction | 2023 |
| Setaj Ahmed Ltd | Transport & logistics | 2019 |
| SEVENTY9 Sports Management Ltd | Arts & recreation | 2025 |
| SFM Pubs Ltd | Hospitality | 2023 |
| SFW Transport Ltd | Transport & logistics | 2018 |
| SG Accountants Limited | Professional & scientific | 2024 |
| SG Group Private Ltd | Wholesale & retail | 2022 |
| SG Legionella Services Ltd | Professional & scientific | 2025 |
| SG Plastering & DRY Lining Limited | Construction | 2008 |
| SGL Protection Ltd | Administrative & support | 2025 |
| SGR 2 Ltd | Real estate | 2026 |
| SGR Cafe Ltd | Hospitality | 2025 |
| SGV Motors Ltd | Wholesale & retail | 2025 |
| Shadow & Spectre Investigations Ltd | Arts & recreation | 2026 |
| Shadow Commercial Ltd | Manufacturing | 2022 |
| Shadow Haulage Ltd | Transport & logistics | 2015 |
| Shake a Shake Forestgate Ltd | Hospitality | 2023 |
| Shakti Partners Ltd | Real estate | 2025 |
| Shakti Trading Ltd | Wholesale & retail | 2016 |
| Shan UK Property Ltd | Real estate | 2018 |
| Shayona 24 Limited | Real estate | 2026 |
| Shayona Pharma Limited | Wholesale & retail | 2023 |
| Shayona Services Limited | Information & communication | 2020 |
| Sheehan Computer Services Limited | Information & communication | 1981 |
| Sheetal Global Ltd | Wholesale & retail | 2026 |
| Shelley Homes Builders Limited | Real estate | 2002 |
| Shelly's Hair and Beauty Ltd | Other services | 2013 |
| Sheng LI 10 Limited | Hospitality | 2026 |
| Sheriff House Management Limited | Professional & scientific | 1990 |
| Shibha Ltd | Health & social care | 2026 |
| Shield Social Care Ltd | Health & social care | 2014 |
| Shift Media (Global) Ltd | Information & communication | 2021 |
| Shill Consulting Limited | Professional & scientific | 2019 |
| Shiloh Haven Group Ltd | Health & social care | 2024 |
| Shine DRY Wall Ltd | Construction | 2021 |
| Shinny Hand Carwash Ltd | Administrative & support | 2023 |
| Shipart Ltd | Transport & logistics | 2025 |
| Shire Community Services Limited | Other services | 2006 |
| Shire Training and Compliance Ltd | Administrative & support | 2023 |
| Shiv Janki Ltd | Wholesale & retail | 2018 |
| Shiv Krish Limited | Professional & scientific | 2016 |
| Shivansh International Limited | Wholesale & retail | 2025 |
| Shoky Trans Ltd | Transport & logistics | 2018 |
| Shonastore Limited | Wholesale & retail | 2025 |
| Shopblitz.Co.Uk Ltd | Wholesale & retail | 2024 |
| Shopping Phase Limited | Wholesale & retail | 2025 |
| Short Stay Lettings Ltd | Real estate | 2019 |
| Shree Gurukrupa Enterprise Ltd | Hospitality | 2022 |
| Shree RAM Food Limited | Wholesale & retail | 2024 |
| Shreeji Food Limited | Hospitality | 2014 |
| Shreeji House Limited | Real estate | 2024 |
| Shreeji Krupa Investments Ltd | Real estate | 2025 |
| Shreeji Krupa Limited | Wholesale & retail | 2016 |
| Shreeji Travel Ltd | Administrative & support | 2009 |
| Shreenathji Investments Limited | Real estate | 2018 |
| Shrijee Ltd | Wholesale & retail | 2026 |
| Shudan Community Interest Company | Education | 2015 |
| Shutter Presser Ltd | Information & communication | 2022 |
| Side Order Catering Ltd | Hospitality | 2026 |
| Sideways Systems Ltd | Wholesale & retail | 2020 |
| Sidill Limited | Construction | 2023 |
| SIF Logistiq Ltd | Transport & logistics | 2025 |
| Sign and Graphic Solutions Ltd | Manufacturing | 2018 |
| Signal Properties Limited | Real estate | 2019 |
| Signalbox Properties Limited | Real estate | 2024 |
| Sikadua Ltd | Real estate | 2025 |
| SIL ALL Services Ltd | Administrative & support | 2019 |
| Silvaway Finance Limited | | 1969 |
| Silver Lion Homes Ltd | Health & social care | 2024 |
| Silver Slippers Ltd | Education | 2024 |
| Silver Street Mini Market Ltd | Wholesale & retail | 2026 |
| Silverline Transport & Recovery Limited | Transport & logistics | 2025 |
| Silversage Ltd | Information & communication | 2008 |
| Simco Acquisitions Limited | Financial services | 2026 |
| Simion Trans Ltd | Administrative & support | 2017 |
| Simionescu Ltd | Transport & logistics | 2022 |
| Simon's Blues Ltd | Wholesale & retail | 2026 |
| Simple-Safety (Northants) Ltd | Professional & scientific | 2023 |
| Simplex Holdings Limited | Financial services | 2025 |