| SEC Group Limited | Extraterritorial | 2007 |
| SEC Property Services Limited | Real estate | 2006 |
| Secondary Glazing Limited | Extraterritorial | 2002 |
| Securicorp Site Security Specialist Group Ltd | Administrative & support | 2023 |
| Sedg Ltd | Transport & logistics | 2025 |
| Selecta Records Limited | Information & communication | 2020 |
| Selrec International Limited | Extraterritorial | 2014 |
| Selrec Trading Limited | Wholesale & retail | 2021 |
| Sendsable Solutions Ltd | Education | 2025 |
| Sense Support Services Ltd | Health & social care | 2023 |
| Serry Global Ltd | Financial services | 2023 |
| Serry International Ltd | Financial services | 2023 |
| SH Project Support Limited | Professional & scientific | 2023 |
| Shafto Way Garage Limited | Wholesale & retail | 2025 |
| Shah's Tradify Ltd | Wholesale & retail | 2025 |
| Share Productions Limited | Information & communication | 2025 |
| Shield Online Marketing Ltd | Professional & scientific | 2012 |
| Shire END Ltd | Hospitality | 2016 |
| Short Break Services Ltd | Health & social care | 2025 |
| Side Effects Limited | Wholesale & retail | 2019 |
| Siesta Blinds Ltd | Manufacturing | 2002 |
| SIESTA2GO Ltd | Manufacturing | 2021 |
| Silent Night Secondary Glazing Ltd | Extraterritorial | 2011 |
| Sisters of Support CIC | Health & social care | 2024 |
| SJM Lashes Ltd | Other services | 2018 |
| Sky Rocket Academy Ltd | Professional & scientific | 2026 |
| SLC Counselling Ltd | Health & social care | 2022 |
| Smart Accessories Tees Ltd | Wholesale & retail | 2020 |
| Smartea Ltd | Wholesale & retail | 2024 |
| SMC Logic Ltd | Information & communication | 2012 |
| Sofar SO Good NE Ltd | Manufacturing | 2019 |
| Solace Legal Ltd | Professional & scientific | 2025 |
| Solway Ridge Ltd | Professional & scientific | 2025 |
| Sonno Haus Ltd | Wholesale & retail | 2024 |
| Sore Paws Veterinary Clinic Ltd | Professional & scientific | 2014 |
| Soretrac (U.K.) Limited | Administrative & support | 1981 |
| Soul Purpose Learning & Life Management Ltd | Health & social care | 2009 |
| SP Fabrication Services Ltd | Manufacturing | 2016 |
| SP Outdoor Solutions LLP | | 2025 |
| Space to Thrive: Health and Fitness Ltd | Health & social care | 2019 |
| Spacedbyid Limited | Other services | 2017 |
| Spark Solutions Group Ltd | Professional & scientific | 2026 |
| Speech Therapy 4 Kids Limited | Health & social care | 2011 |
| Spiraretech Ltd | Professional & scientific | 2025 |
| Spring Garden Cleaning Limited | Administrative & support | 2022 |
| Squirrel Bars Ltd | Hospitality | 2023 |
| ST Vision Limited | Health & social care | 2014 |
| Stable Hearth Limited | Hospitality | 2017 |
| Star Properties NE Limited | Real estate | 2023 |
| Star Recruitment North East Ltd | Administrative & support | 2021 |
| Starlight Windows Limited | Manufacturing | 1997 |
| Starshack Ltd | Hospitality | 2026 |
| Starship Ventures Limited | Professional & scientific | 2023 |
| Steadfast Capital Ltd | Real estate | 2024 |
| Steam Machine Brewing Company Ltd | Manufacturing | 2015 |
| Stella Commercial Diving Services Ltd | Construction | 2014 |
| Stemp Sullivan Rope Access Limited | Manufacturing | 2024 |
| Sterling Homes and Properties Ltd | Real estate | 2020 |
| Steve Lambert Transport Ltd | Transport & logistics | 2015 |
| Steven Turnbull Resource Ltd. | Administrative & support | 2021 |
| Stiller Group South Limited | Information & communication | 1948 |
| Stiller Warehousing & Distribution Limited | Transport & logistics | 1996 |
| Stiller Warehousing Ltd | Transport & logistics | 1999 |
| Stone Element Limited | Construction | 2014 |
| Stonebox Home Delivered Limited | Wholesale & retail | 2024 |
| Stoneleigh Family Butchers (Weybridge) Ltd | Wholesale & retail | 2018 |
| Stoneleigh Family Butchers Ltd | Wholesale & retail | 2016 |
| Stoneleigh Property Holdings Limited | Financial services | 2021 |
| Stormsea Limited | Real estate | 2025 |
| Stuart Burton Holdings Ltd | Financial services | 2020 |
| Studioanyo Architects Limited | Professional & scientific | 2011 |
| Studioanyo Group Limited | Financial services | 2022 |
| Sumo Tech Ltd | Information & communication | 2019 |
| Sunshine Websites Ltd | Information & communication | 2025 |
| Supreme Brickwork NE Limited | Construction | 2024 |
| Supreme Group NE Limited | Financial services | 2024 |
| Supreme Timber Ltd | Wholesale & retail | 2020 |
| Surface Technologies Ltd | Construction | 2023 |
| Surge Sync Media Ltd | Professional & scientific | 2024 |
| Swale Systems Ltd | Administrative & support | 2021 |
| Sweet Cheeks Ltd | Wholesale & retail | 2020 |
| Synkro Ltd | Professional & scientific | 2026 |
| System Wargacki Ltd | Professional & scientific | 2023 |
| Sznajder Ltd | Transport & logistics | 2020 |
| T M Catering (NE) Ltd | Hospitality | 2019 |
| T.H.E 4S Group Limited | Construction | 2026 |
| T.H.E Freshfix Sandwich Co Ltd | Hospitality | 2025 |
| T.H.E Shepherd Holdings Ltd | Financial services | 2025 |
| Talpoi Ltd | Transport & logistics | 2021 |
| Tamarind Hill Press Limited | Information & communication | 2022 |
| Tanned UP Aycliffe Ltd | Wholesale & retail | 2025 |
| Tanned UP Shildon Ltd | Wholesale & retail | 2025 |
| Taylored Inventories Ltd | Real estate | 2020 |
| Taytil Consulting Ltd | Professional & scientific | 2019 |
| Tazz & Co Limited | Information & communication | 2025 |
| Tbox Limited | Information & communication | 2013 |
| TC Solutions (North East) Ltd | Construction | 2022 |
| Technical Learning Company Ltd | Education | 2025 |
| Techwax Limited | Manufacturing | 1991 |
| Ted&Bear Holdings Ltd | Financial services | 2024 |