| Select Inns Limited | Hospitality | 2017 |
| Selle Italia (UK) Limited | Professional & scientific | 2017 |
| Sellist Ltd | Wholesale & retail | 2024 |
| Sendco Hub Ltd | Information & communication | 2026 |
| Sentes.Ry Limited | Wholesale & retail | 2026 |
| Sentinels Group UK Ltd | Wholesale & retail | 2021 |
| Sepia Health Limited | Professional & scientific | 2018 |
| Serava Limited | Hospitality | 2026 |
| Serban Logistics Ltd | Transport & logistics | 2017 |
| Serenity Luxe Jewellery Ltd | Wholesale & retail | 2024 |
| Serious.Members.Only Limited | Other services | 2025 |
| SET Straight Limited | Other services | 2023 |
| Seval Barber Limited | Other services | 2025 |
| Seven @ Eleven Ltd | Wholesale & retail | 2021 |
| Seven Arms Limited | Hospitality | 2023 |
| Seven G Power Ltd | Construction | 2026 |
| SF Independent Specialists Limited | Professional & scientific | 2018 |
| Sfhs Properties Ltd | Real estate | 2023 |
| Sfks Builders Limited | Other services | 2013 |
| SG Accountancy Solutions Ltd | Professional & scientific | 2020 |
| SGR Audio Visual Ltd | Administrative & support | 2020 |
| SGR Commercial Ltd | Real estate | 2022 |
| Shad & Sons Ltd | Wholesale & retail | 2026 |
| Shaecc Ltd | Information & communication | 2013 |
| Shafiq and Sons Limited | Wholesale & retail | 2004 |
| Shahs Solstice Market Ltd | Wholesale & retail | 2025 |
| Shake Rattle N Roll Ltd | Hospitality | 2013 |
| Shaker Estate Group Ltd | Hospitality | 2026 |
| Shane’S of Dunstable Ltd | Wholesale & retail | 2022 |
| Shannak Orthopaedics Limited | Health & social care | 2023 |
| Sharp Arts Ltd | Arts & recreation | 2026 |
| Shaw and Gadsden Limited | Construction | 2008 |
| Shawllzz Limited | Information & communication | 2024 |
| SHC Waste Brokerage Limited | Wholesale & retail | 2017 |
| SHE CAN Prosper CIC | Education | 2025 |
| SHE Goes Wear Limited | Wholesale & retail | 2023 |
| She's a Spark Ltd | Construction | 2022 |
| She's Healing Limited | Manufacturing | 2025 |
| Shelleto's Kitchen Ltd | Hospitality | 2022 |
| Shelton Way Limited | Hospitality | 2025 |
| Sheltura Housing CIC | Hospitality | 2026 |
| SHF (MK) Limited | Administrative & support | 2019 |
| Shifts-In Limited | Construction | 2025 |
| Shikata Ltd | Wholesale & retail | 2025 |
| Shinwari Motors UK Ltd | Transport & logistics | 2025 |
| SHINWARI9696 Ltd | Administrative & support | 2023 |
| Shipley Tenpin Bowling Limited | Arts & recreation | 2015 |
| Shire Finance Limited | Financial services | 1990 |
| Shire Property Management Limited | Real estate | 2023 |
| Shire Property Operations Limited | Real estate | 2026 |
| Shivers Above Madness Ltd | Information & communication | 2014 |
| SHO Building Services Ltd | Construction | 2022 |
| Shona Claire Beauty Salon Limited | Other services | 2025 |
| Shoot Services Ltd. | Other services | 2001 |
| Shree Keshav Ltd | Wholesale & retail | 2023 |
| Shreeji International Limited | Wholesale & retail | 2016 |
| Shulev Ltd | Transport & logistics | 2019 |
| Sibiga Fight Gear Limited | Wholesale & retail | 2020 |
| Sibslabs Ltd | Manufacturing | 2019 |
| Sicanta Flat Management Limited | Households | 1986 |
| Sida Construction Group Limited | Construction | 2005 |
| Sida Consultancy Limited | Professional & scientific | 2011 |
| Sida Corporation Limited | Real estate | 2005 |
| Sida Supplies Limited | Wholesale & retail | 2012 |
| Sidar Estates (Central London) Limited | Real estate | 2017 |
| Siddhivinayak Properties Ltd | Real estate | 2022 |
| Side Bites Ltd | Hospitality | 2025 |
| Sidelineprints Ltd | Wholesale & retail | 2026 |
| Sierra Marketing Limited | Information & communication | 2018 |
| SIG Security Solutions Ltd | Administrative & support | 2026 |
| Sightline Solutions Limited | Construction | 2011 |
| Signature Care & Support Limited | Health & social care | 2023 |
| Signature Flatbreads (UK) Ltd | Manufacturing | 2014 |
| Silver Arrow Archery Club NO 2 Limited | Arts & recreation | 2019 |
| Silver Oaks Holdings Ltd | Real estate | 2020 |
| Silver Screen Services (UK) Ltd | Transport & logistics | 2012 |
| Silver Trans Ltd | Transport & logistics | 2013 |
| Silver Tree Care Limited | Health & social care | 2008 |
| Silverhill Associates Ltd | Administrative & support | 2011 |
| Silverline Car Hire Limited | Administrative & support | 2018 |
| Silverwood Property Holdings Limited | Real estate | 2020 |
| Silvester's Plumbing and Heating Home Counties Limited | Construction | 2020 |
| Silvian Trans Ltd | Transport & logistics | 2020 |
| Simau Ltd | Wholesale & retail | 2024 |
| Simi Construct Limited | Construction | 2025 |
| Simple-Smarthomes Limited | Information & communication | 2024 |
| Simply ID Limited | Construction | 2023 |
| Simply Security Contractors Ltd | Construction | 2023 |
| Simplyinvest Ltd | Construction | 2024 |
| Simplystaysuk Ltd | Real estate | 2023 |
| Sirius Digital Solutions Ltd | Information & communication | 2009 |
| SIS Team Ltd | Education | 2025 |
| Site Monitoring and Surveying Services Ltd | Professional & scientific | 2018 |
| Site Serve UK Ltd | Administrative & support | 2026 |
| Sivam & Sons PVT Ltd | Wholesale & retail | 2022 |
| Sivapuri Properties Ltd | Real estate | 2022 |
| SIXTEEN30 Realty Ltd | Real estate | 2023 |
| Sj&M Consultancy Ltd | Professional & scientific | 2024 |
| SJB Innovations Limited | Construction | 2026 |
| SJC Automotive Ltd | Manufacturing | 2025 |