| Shotton-Hogg Ltd | Hospitality | 2022 |
| Shotz Fitness Ltd | Arts & recreation | 2020 |
| Shout Digital Limited | Information & communication | 2009 |
| Shout Digital UK Limited | Information & communication | 2020 |
| SHOW2 Ltd | Professional & scientific | 2023 |
| Showermania Limited | Wholesale & retail | 2008 |
| Shpa Properties Ltd | Construction | 2024 |
| Shree Annapurna Ltd | Hospitality | 2025 |
| Shree Rama Limited | Real estate | 2023 |
| Shree TRT Services Ltd | Information & communication | 2013 |
| Shreeji's & Sons Ltd | Hospitality | 2022 |
| Shreenathji Properties Ltd | Households | 2024 |
| Shreyansh Healthcare Limited | Public administration | 2026 |
| Shribes Limited | Administrative & support | 2023 |
| Shrubgarden Limited | Agriculture & fishing | 2022 |
| SHS Event Consultancy Ltd | Arts & recreation | 2021 |
| Shudder Films Limited | Information & communication | 2009 |
| Shuffle Thump Limited | Information & communication | 2023 |
| Shumon Ltd | Real estate | 2021 |
| Shuttle Software Ltd | Information & communication | 2024 |
| Shuttleworth Property and Construction Limited | Construction | 2016 |
| SHY Bairns Collective Ltd. | Arts & recreation | 2021 |
| SHY Bairns Consulting Ltd | Information & communication | 2026 |
| Siam (NE) Cafe Ltd | Hospitality | 2016 |
| Siar Pizza Ltd | Hospitality | 2023 |
| SIB & Co Services Ltd | Construction | 2026 |
| SIB SIB Ltd | Hospitality | 2025 |
| Sibel NE Ltd | Hospitality | 2023 |
| Sibling Synergy Ltd | Professional & scientific | 2018 |
| Sibu KIA Ltd | Hospitality | 2024 |
| Sibylle Clerey Interiors Limited | Professional & scientific | 2025 |
| Sich Services Ltd | Other services | 2025 |
| Sick Stick Creations Ltd | Wholesale & retail | 2021 |
| Sicl Mints Enterprises Limited | Education | 2025 |
| Sicl Taxis Limited | Transport & logistics | 2025 |
| Siddh Enterprise Ltd | Wholesale & retail | 2023 |
| Siddique Style Ltd | Real estate | 2019 |
| Sidney Court Management Company Limited | Households | 1993 |
| Sidney Gardens Management Company Limited | Households | 2008 |
| Sidney Kidney Medical Consultancy Limited | Health & social care | 2012 |
| Siemens Energy Industrial Turbomachinery Limited | Manufacturing | 2003 |
| Siemens Energy Limited | Manufacturing | 1959 |
| Sierra Clara Limited | Construction | 2024 |
| Sierra FBA Ltd | Wholesale & retail | 2022 |
| Sightdirect Limited | Health & social care | 2003 |
| Sightlines Initiative Ltd | Education | 2013 |
| Sigmaxl Ltd | Professional & scientific | 2021 |
| Sign Pro Limited | Manufacturing | 2007 |
| Signal Construction Limited | Construction | 2024 |
| Signal Professional Solutions Ltd | Health & social care | 2022 |
| Signalnoise Studio Ltd | Arts & recreation | 2021 |
| Signature Group NE Limited | Public administration | 2019 |
| Signature Home Projects Limited | Construction | 2026 |
| Signature Perfumes Ltd | Wholesale & retail | 2018 |
| Signature Skin Design Ltd | Other services | 2021 |
| Signs/Resin Flooring Near ME North East Limited | Construction | 2025 |
| Sigá Studio Ltd | Arts & recreation | 2025 |
| Sikono Ltd | Professional & scientific | 2021 |
| Silbo Limited | Information & communication | 2000 |
| Silent Games Ltd | Information & communication | 2018 |
| Silent Nest Ltd | Hospitality | 2025 |
| Silent Tribe Ltd | Education | 2025 |
| Silicon Devices Limited | Wholesale & retail | 2021 |
| Siliskin Ltd | Wholesale & retail | 2024 |
| Silk and Wool Limited | Wholesale & retail | 2024 |
| Silk Road Wear Ltd | Wholesale & retail | 2025 |
| Silver Flowe Limited | Professional & scientific | 2010 |
| Silver Note Ltd | Real estate | 2022 |
| Silver Properties Newcastle Limited | Real estate | 2023 |
| Silver Street (Durham) Properties Limited | Hospitality | 1999 |
| Silver Tulip Recruitment Ltd | Administrative & support | 2018 |
| SILVER21 Limited | Hospitality | 2021 |
| Silverfirs Limited | Real estate | 2016 |
| Silvergate Global Ltd | Wholesale & retail | 2025 |
| Silverlink Broadcast Limited | Information & communication | 2005 |
| Silverlink Properties Limited | Construction | 1989 |
| Silverlink Stephenson Limited | Construction | 2004 |
| Silvermere Construction Limited | Construction | 2013 |
| Silverseven Limited | Real estate | 2007 |
| Silverstone Building Consultancy Limited | Administrative & support | 2009 |
| Silverstone Group Holdings Limited | Financial services | 2026 |
| Silverstone Residential Surveys Limited | Real estate | 2017 |
| Silverview Limited | Real estate | 1993 |
| SIM Group (Yorkshire) Limited | Information & communication | 2025 |
| Sima Saremi Ltd | Real estate | 2022 |
| Simba Holdings North East Limited | Health & social care | 2019 |
| Simba N.E Ltd | Hospitality | 2024 |
| Simba Shore Ltd | Information & communication | 2026 |
| Similytics Limited | Information & communication | 2022 |
| Simod UK Limited | Health & social care | 2021 |
| Simonbriton Ltd | Professional & scientific | 2020 |
| Simonside Properties Limited | Professional & scientific | 1990 |
| Simpill Ltd | Wholesale & retail | 2012 |
| Simple Solutions Europe Ltd | Construction | 2010 |
| Simple Target Ltd | Professional & scientific | 2014 |
| Simplemark Ltd | Extraterritorial | 2000 |
| Simpli Print Group Ltd | Manufacturing | 2024 |
| Simplicity Energy Limited | Energy | 2017 |
| Simply Fresh Cleaning Ltd | Administrative & support | 2025 |
| Simply Greek (NE) Ltd | Hospitality | 2017 |