| Smart ASH Limited | Wholesale & retail | 2000 |
| Smart Blood TAG Ltd | Manufacturing | 2025 |
| Smart Choice Chef Ltd | Hospitality | 2020 |
| Smart Electrical Northern Limited | Other services | 2017 |
| Smart Gadgets Plus Ltd | Extraterritorial | 2025 |
| Smart Homes Newcastle Limited | Construction | 2015 |
| Smart IT Consultancy Limited | Wholesale & retail | 2022 |
| Smart IT Support Ltd | Information & communication | 2008 |
| Smart Move Lettings Ltd | Real estate | 2017 |
| Smart Nova Property Investment Limited | Real estate | 2024 |
| Smart Office Property Limited | Real estate | 2018 |
| Smart Office Supplies (North East) Limited | Professional & scientific | 2006 |
| Smart Office Systems Limited | Wholesale & retail | 2002 |
| Smart Real Estate Limited | Financial services | 1995 |
| Smart Repairs (N.E.) Ltd | Wholesale & retail | 2022 |
| Smarter Solutions 4 U Ltd | Administrative & support | 2016 |
| Smartspanner Ltd | Information & communication | 2013 |
| Smartstack Limited | Professional & scientific | 2021 |
| SMB Homes Ltd | Real estate | 2019 |
| Smile Group Holdings Ltd | Administrative & support | 2025 |
| Smiles Ecom Ltd | Wholesale & retail | 2017 |
| Smilesgoms Limited | Health & social care | 2018 |
| Smiley's Gateshead Ltd | Other services | 2018 |
| Smileys Assets Ltd | Real estate | 2026 |
| Smileys Properties Ltd | Real estate | 2023 |
| Smithburn Construction Ltd | Construction | 2025 |
| Smith’S Eco Heating & Plumbing Ltd | Construction | 2023 |
| Snahir Ltd | Real estate | 2016 |
| Snahir Retail Limited | Wholesale & retail | 2016 |
| Snake OIL and Chicken Lips Ltd | Professional & scientific | 2018 |
| Snapfast Ltd | Wholesale & retail | 2019 |
| Snappys Recovery Ltd | Wholesale & retail | 2021 |
| Snapsaver Ltd | Information & communication | 2015 |
| Snazzy's DRY Cleaning Ltd | Other services | 2025 |
| SNC Estates Ltd | Real estate | 2020 |
| Sndl Limited | Real estate | 2022 |
| Snowball Newcastle Limited | Real estate | 2020 |
| SO Venture Group Ltd | Health & social care | 2026 |
| Soave Property Group Ltd | Real estate | 2026 |
| Soccer Sensations Hull Limited | Arts & recreation | 2005 |
| Soccer Sensations Teesside Limited | Administrative & support | 2018 |
| Soccer Villages UK Limited | Financial services | 2008 |
| Socexp Limited | Administrative & support | 2015 |
| Social Butterflies Group Ltd | Education | 2022 |
| Social CEO UK Limited | Professional & scientific | 2026 |
| Social Impact Insights Ltd | Financial services | 2024 |
| Social Inclusion Through Sport CIC | Arts & recreation | 2024 |
| Social Seed Limited | Professional & scientific | 2025 |
| Society for Education Limited | Education | 2003 |
| Society Matters Community Interest Company | Public administration | 2012 |
| Socketts Ltd | Wholesale & retail | 2020 |
| Socuk Ltd | Real estate | 2021 |
| Soga Ltd | Real estate | 2020 |
| Soho Gateshead Property Group Limited | Real estate | 2020 |
| Soho Tavern Gateshead Ltd | Hospitality | 2024 |
| Soivah Limited | Real estate | 2024 |
| Soku Ltd | Hospitality | 2025 |
| SOL Coffee Ltd | Hospitality | 2022 |
| SOL Hair Studio Limited | Other services | 2024 |
| Soldun Ltd | Real estate | 2019 |
| Solex Paints Ltd | Wholesale & retail | 2018 |
| Solid Pro Vehicles Ltd | Wholesale & retail | 2026 |
| Solidverse Logistics Limited | Transport & logistics | 2026 |
| Solidware Ltd | Information & communication | 2014 |
| Solosoft Limited | Extraterritorial | 2018 |
| Solution Precision CNC Limited | Manufacturing | 2019 |
| Solva Health Ltd | Wholesale & retail | 2026 |
| Solved Design Limited | Information & communication | 2024 |
| Somerset Surgical Services Ltd | Health & social care | 2011 |
| Songbird Music Management Ltd | Arts & recreation | 2019 |
| Sorceress Tattoo Limited | Other services | 2021 |
| SOS CAN DO Communications Limited | Information & communication | 2014 |
| SOS Group Limited | Professional & scientific | 2006 |
| Sos-It Limited | Information & communication | 2013 |
| Soul Curry Ltd | Hospitality | 2019 |
| Soundrift.Ai Ltd | Manufacturing | 2025 |
| Sounds Like Production Ltd | Information & communication | 2026 |
| South Hereford Garages Limited | Extraterritorial | 1973 |
| South Hereford Garages Trade Parts LLP | | 2007 |
| South Shore Catering Ltd | Hospitality | 2023 |
| South Shore Developments Limited | Real estate | 2004 |
| South Tees Medical Ltd | Health & social care | 2016 |
| South West London College Limited | Education | 2024 |
| Southend Plaice Fish &Chips Ltd | Hospitality | 2024 |
| Southend Plaice NE Ltd | Hospitality | 2026 |
| Southend Properties (NE) Ltd | Real estate | 2020 |
| Southern Consulting UK Limited | Professional & scientific | 2009 |
| Southern Tyres (Commercial) Limited | Extraterritorial | 2015 |
| Southwick Fish and Chips Limited | Hospitality | 2025 |
| Southwick Foods Ltd | Hospitality | 2016 |
| Southwick Properties Limited | Real estate | 2017 |
| Sovereign Nominees Limited | Real estate | 2011 |
| Sovereign Nominees NO.2 Limited | Real estate | 2011 |
| Sovereign Point Freehold Limited | Real estate | 2024 |
| Sovereign Reversions Limited | Real estate | 1992 |
| Spa Retailing Ltd | Wholesale & retail | 2019 |
| Space Direct Ltd | Construction | 2014 |
| Spanish City Ltd | Arts & recreation | 2003 |
| Spark Energy Group Limited | Real estate | 2018 |
| Spark Health and Fitness Limited | Arts & recreation | 2014 |