| Specialist Four by Four Services Limited | Wholesale & retail | 2008 |
| Specialist Site Security Ltd | Financial services | 2018 |
| Speedy Plus Ltd | Hospitality | 2025 |
| Spice Lounge (B.A) Ltd | Hospitality | 2021 |
| Splint Doctor Limited | Health & social care | 2025 |
| Spotless Car Wash Bishop Limited | Administrative & support | 2024 |
| Spotless Car Wash Ltd | Administrative & support | 2026 |
| Spray Technologies Bespoke Joinery Limited | Construction | 2019 |
| Sprayclad (B.A.) Ltd | Manufacturing | 2023 |
| Spraycladuk NE Ltd | Construction | 2022 |
| Spraycladuk NE Properties Ltd | Real estate | 2026 |
| Spring Garden Developments Limited | Real estate | 2017 |
| Sprinters Sportswear Ltd | Manufacturing | 2019 |
| Sprout & SIP Ltd | Hospitality | 2026 |
| Spud and Roll Ltd | Hospitality | 2025 |
| SR Construction NE Ltd | Construction | 2026 |
| SR Consultancy & Management Water Solutions Ltd | Professional & scientific | 2021 |
| SR Electrical NE Limited | Construction | 2025 |
| SSC Property Investments Limited | Real estate | 2016 |
| ST Helen Car Valeting Limited | Administrative & support | 2024 |
| ST Marys Vale Management Company Limited | Households | 2020 |
| ST Michel and ALL Angels Ltd | Construction | 2018 |
| ST Ronas Kensington Ltd | Real estate | 2025 |
| ST. John's in Weardale Auction Mart Company, Limited | Real estate | 1895 |
| Stadium Way Developments Limited | Real estate | 2018 |
| Stage & Screen Productions Limited | Arts & recreation | 2016 |
| Stage Door Enterprises Limited | Hospitality | 2021 |
| Staindrop Management Company Limited | Households | 2015 |
| Stanhope Motor Services Limited(The) | Extraterritorial | 1933 |
| Stanhope Supermarket Ltd | Wholesale & retail | 2017 |
| Stanhope Swimming Pool Ltd | Arts & recreation | 2008 |
| Stanhope Travel Ltd | Administrative & support | 2007 |
| Stanier Consulting Limited | Professional & scientific | 2023 |
| Stanier Property Services Ltd | Hospitality | 2023 |
| Stanroph Contracting and Consultancy Limited | Construction | 2019 |
| Station View Limited | Real estate | 2019 |
| Stayne Ltd | Hospitality | 2023 |
| Steadman-Lloyd Ltd | Real estate | 2014 |
| Steam Ahead CIC | Education | 2018 |
| Steel Catering Limited | Hospitality | 2024 |
| Steptech Controls Ltd | Manufacturing | 2014 |
| Steve Garrett Dog Security Limited | Financial services | 2025 |
| Steven Raine Associates Ltd | Administrative & support | 2025 |
| STH Group Holdings Ltd | Financial services | 2025 |
| Stish Ltd | Other services | 2017 |
| Stobart Solutions Limited | Professional & scientific | 2025 |
| Stockton Casting Company Limited(The) | Manufacturing | 1947 |
| Stoke the Flame CIC | Education | 2022 |
| Stone Carrs Limited | Hospitality | 2016 |
| Stone Craft Paving and Roofing Ltd | Construction | 2025 |
| Stone Property Development Ltd | Households | 2021 |
| Stone Valley Interiors Ltd | Construction | 2020 |
| Store & More NE Limited | Transport & logistics | 2025 |
| Structassure Ltd | Administrative & support | 2023 |
| STS (NE) Ltd | Professional & scientific | 2025 |
| Stuart Hall & Co Limited | Professional & scientific | 2009 |
| Stuart Martin Limited | Construction | 2009 |
| Studio 96 NE Ltd | Other services | 2025 |
| Stylebook Directory Ltd | Information & communication | 2019 |
| Stylebook Holdings Ltd | Information & communication | 2024 |
| Stylebook UK Ltd | Information & communication | 2024 |
| SUE Garwood Interior Design Limited | Professional & scientific | 2023 |
| Sunesis Training & Consultancy Limited | Professional & scientific | 2012 |
| Sunniside Developments Ltd | Construction | 2023 |
| Sunnybank Farm and Land Limited | Professional & scientific | 2025 |
| Sunset Getaways Travel Company Ltd | Administrative & support | 2023 |
| Super Power Toys Ltd | Wholesale & retail | 2020 |
| Supply N Fit Carpets & Flooring Ltd | Construction | 2016 |
| Supremeplump Ltd | Other services | 2024 |
| Supremetanuk Ltd | Other services | 2022 |
| Supremetanuk Salon Ltd | Other services | 2022 |
| Susteco Systems Limited | Professional & scientific | 2009 |
| Swan Site Engineering (NE) Ltd | Construction | 2022 |
| Swanland Park Management Company Limited | Households | 2017 |
| Sweet Rose Ice Cream Parlour Limited | Hospitality | 2018 |
| Swift Timber Homes Limited | Manufacturing | 2000 |
| Switch on Rentals Limited | Other services | 2017 |
| Swsd Promotions Limited | Wholesale & retail | 2025 |
| Sycamore Chase Management Company Limited | Households | 2013 |
| Sylvatica Limited | Administrative & support | 2013 |
| T & S Bespoke Kitchens Ltd | Manufacturing | 2007 |
| T J Tarn Haulage Limited | Extraterritorial | 2001 |
| T N Commercials Ltd | Wholesale & retail | 2011 |
| T&D Consulting Services Limited | Other services | 2018 |
| T. Linsley & SON Ltd | Wholesale & retail | 2007 |
| T. Manners & Sons (Developments) Limited | Professional & scientific | 1993 |
| T.Manners & Sons Limited | Construction | 1916 |
| Tactic North East CIC | Arts & recreation | 2023 |
| Tallow Financial Planning Limited | Financial services | 2019 |
| Tandem Properties Limited | Administrative & support | 2007 |
| TAP Geothermal Limited | Construction | 2021 |
| TAP Solar Limited | Construction | 2021 |
| TAP Trading Limited | Arts & recreation | 2012 |
| Taste of China (KL) Limited | Hospitality | 2021 |
| Taste of India (Auckland) Ltd | Administrative & support | 2018 |
| Taste of Teesdale Ltd | Manufacturing | 2024 |
| Taylored Steel & Specialised Engineering Services Ltd | Construction | 2026 |
| Taylormariusestate Ltd | Real estate | 2025 |
| Taylors Plumbing and Maintenance Ltd | Construction | 2020 |
| TBQ Management Ltd | Hospitality | 2026 |