| Smart Property NE Ltd | Real estate | 2025 |
| Smart TAB Servco Ltd | Other services | 2026 |
| Smart TAN UK Limited | Other services | 2011 |
| Smart Tech NCL Limited | Construction | 2025 |
| Smart Tech NE Limited | Wholesale & retail | 2021 |
| Smart Utility Consultancy Ltd | Administrative & support | 2026 |
| Smart Works North East | Administrative & support | 2017 |
| Smartcoater Limited | Extraterritorial | 2025 |
| Smartlec Systems Ltd | Construction | 2021 |
| Smartshoppinguk Ltd | Wholesale & retail | 2026 |
| Smash Life Ltd | Health & social care | 2024 |
| Smashed Geordies Ltd | Hospitality | 2025 |
| Smashspace Limited | Arts & recreation | 2022 |
| Smcb Consultants Ltd | Manufacturing | 2012 |
| SME Accountants and Business Advisors Ltd | Professional & scientific | 2019 |
| SME Business Chat Ltd | Administrative & support | 2014 |
| SME Centre of Excellence (Cofe) Northumberland Limited | Information & communication | 2018 |
| SME Utility Advice Ltd | Professional & scientific | 2025 |
| SMF CAD Solutions Ltd | Construction | 2017 |
| Smilax Ltd | Wholesale & retail | 2023 |
| Smile and Travel Ltd | Administrative & support | 2025 |
| Smile Capital (NE) Ltd | Real estate | 2025 |
| Smile for Life Children's Charity | Other services | 2009 |
| Smile Fundraising Ltd | Other services | 2013 |
| Smiles Health and Home Care Ltd | Health & social care | 2025 |
| Smith & Co Properties NE Ltd | Real estate | 2023 |
| Smith Barbering Limited | Other services | 2024 |
| Smith Invest Ltd | Real estate | 2024 |
| Smith Invest Sourcing Ltd | Real estate | 2024 |
| Smithm Limited | Wholesale & retail | 2025 |
| Smiths Shiprepairers North Shields Limited | Professional & scientific | 1966 |
| Smithwood Ventures Limited | Real estate | 2025 |
| Smithys Security Ltd | Construction | 2024 |
| Smjr Consultancy Limited | Other services | 2013 |
| SMK North East LLP | | 2009 |
| Smmr Ltd | Professional & scientific | 2023 |
| Smoke and Heritage Ltd | Hospitality | 2024 |
| Smoke on Grill Ltd | Hospitality | 2026 |
| Smoked N Grilled Ltd | Hospitality | 2024 |
| Smokies Entertainments Limited | Hospitality | 1975 |
| Smotto Limited | Hospitality | 2024 |
| SMT Electrical Contractors Limited | Construction | 1997 |
| Smugglers Cove Management Limited | Real estate | 2007 |
| Smuggling Duds Ltd | Wholesale & retail | 2006 |
| Smurk Inc Ltd | Information & communication | 2015 |
| SNA Whickham Barber Shop Ltd | Other services | 2019 |
| Snahira Limited | Wholesale & retail | 2017 |
| Snahirfr Limited | Wholesale & retail | 2017 |
| Snahirhr Limited | Wholesale & retail | 2017 |
| Snahirnr Limited | Wholesale & retail | 2017 |
| Snahirsa Limited | Wholesale & retail | 2017 |
| Snahirsr Limited | Wholesale & retail | 2017 |
| Snaparazzi Photobooths Limited | Professional & scientific | 2014 |
| Snar Convenience Store Ltd | Wholesale & retail | 2025 |
| SNC Distributions Ltd | Wholesale & retail | 2026 |
| Sncg Ecoscapes Ltd | Agriculture & fishing | 2013 |
| Sncube Healthcare Limited | Health & social care | 2016 |
| Sneha Estates Limited | Real estate | 2025 |
| Snehareddy Ltd | Wholesale & retail | 2023 |
| SNG Driving School Limited | Education | 2026 |
| SNH Estates Ltd | Real estate | 2026 |
| Snide Limited | Wholesale & retail | 2025 |
| Snkr Properties Ltd | Real estate | 2019 |
| SNM Investments Ltd | Professional & scientific | 2012 |
| SNM Private Limited | Other services | 2018 |
| SNN Travels Limited | Administrative & support | 2024 |
| Snob Clothing Ltd | Wholesale & retail | 2015 |
| Snow Wise Experience Limited | Professional & scientific | 2024 |
| Snowden Interiors Limited | Professional & scientific | 2020 |
| Snowdrop Systems Limited | Information & communication | 1991 |
| Snowshock Ltd | Manufacturing | 2011 |
| SNP Global Ltd | Wholesale & retail | 2017 |
| Snug Sauna Limited | Arts & recreation | 2024 |
| Snugyoga Limited | Arts & recreation | 2019 |
| Snusher Safety Solutions Ltd | Professional & scientific | 2025 |
| SO Beautiful Skin Limited | Other services | 2023 |
| SO Glow Tanning Ltd | Wholesale & retail | 2025 |
| SO Many Stories Limited | Information & communication | 2023 |
| SO to Company Ltd | Professional & scientific | 2011 |
| So-Cinematic Ltd | Information & communication | 2023 |
| SOA Rent a Car Ltd | Administrative & support | 2023 |
| Soapbox Bars Ltd | Hospitality | 2024 |
| Soar Build Limited | Construction | 2006 |
| Sochia Care Ltd | Health & social care | 2025 |
| Social GP Limited | Financial services | 2014 |
| Social Leisure Ltd | Hospitality | 2022 |
| Social Plus Limited | Professional & scientific | 2018 |
| Social Software Solution Ltd | Information & communication | 2025 |
| Social Syrup Ltd | Professional & scientific | 2022 |
| Social Value Delivery Solutions Limited | Professional & scientific | 2024 |
| Social Value Limited | Professional & scientific | 2018 |
| Society of Business Lawyers Ltd | Other services | 2019 |
| Society of Commercial Accountants.Limited | Other services | 1943 |
| Society of International Accounting Technicians | Other services | 2003 |
| SOE Innovations Ltd | Professional & scientific | 2025 |
| Soft Life Studios Events Limited | Administrative & support | 2026 |
| Softly Limited | Information & communication | 2025 |
| Software Alchemist Limited | Information & communication | 2017 |
| Software for Information Theoretic Applications Limited | Information & communication | 2023 |
| Software for People Limited | Information & communication | 1993 |