| Spectrum Portfolio Limited | Financial services | 2012 |
| Splink Industries Ltd | Other services | 2019 |
| Sportlands Limited | Administrative & support | 1997 |
| Sports and Prestige of Lichfield Limited | Wholesale & retail | 2018 |
| Spot North East Ltd | Information & communication | 2025 |
| Spray TAN & Beauty Teesside Ltd | Other services | 2026 |
| Springwell Developments Limited | Real estate | 2002 |
| SR Family Holdings Ltd | Real estate | 2018 |
| SR Property Partnership LLP | | 2018 |
| SR WP Ltd | Administrative & support | 2024 |
| SRI Sakhi Ltd | Real estate | 2024 |
| SRK Business Solutions Ltd | Professional & scientific | 2024 |
| SRM Medics Ltd | Health & social care | 2023 |
| SRX North East Limited | Administrative & support | 2011 |
| SS Inspection Services Ltd | Professional & scientific | 2013 |
| Ssms Properties Ltd | Real estate | 2024 |
| ST Construction Management Limited | Professional & scientific | 2012 |
| ST James Asset Management Limited | Real estate | 2016 |
| ST James' Midlands Ltd | Construction | 2023 |
| ST James' View Ltd | Real estate | 2021 |
| ST Project Management Consultancy Limited | Professional & scientific | 2014 |
| Stainton Lighting Design Services Limited | Manufacturing | 2006 |
| Stans Properties Ltd | Real estate | 2021 |
| Star Painting and Cleaning Limited | Administrative & support | 2013 |
| Stat Inspection Services Ltd | Professional & scientific | 2007 |
| Station RD Barbers (NE) Ltd | Other services | 2026 |
| Stavropoulos Property Holdings Ltd | Real estate | 2018 |
| Stavropoulos Property Partnership LLP | | 2018 |
| Stayngo Ltd | Hospitality | 2025 |
| Steel River Energy Limited | Financial services | 2023 |
| Steele Management Consultancy Limited | Professional & scientific | 2016 |
| Stephen Hogg Consultancy Ltd | Professional & scientific | 2018 |
| Stephen Twell Developments Limited | Real estate | 2019 |
| Stephen Twell LLP | | 2019 |
| Stephen Wheatley Inspection Ltd | Manufacturing | 2012 |
| Steralyx Labs Ltd | Wholesale & retail | 2025 |
| Sterling Edwards Partnership LLP | | 2020 |
| Stickyplastics Ltd | Professional & scientific | 2023 |
| Stimpson Family Holdings Ltd | Real estate | 2021 |
| Stimpson Family Partnership LLP | | 2021 |
| STM GRP PAY Limited | Administrative & support | 2018 |
| Stobie Electrical Ltd | Construction | 2018 |
| Stockton Machine Company Limited | Manufacturing | 2004 |
| Stone Family Holdings Ltd | Real estate | 2018 |
| Stone Family Partnership LLP | | 2018 |
| Stonehaven Stays Ltd | Real estate | 2024 |
| Storage and Handling Equipment Limited | Wholesale & retail | 1999 |
| Storcop Limited | Administrative & support | 2025 |
| Store Stack Limited | Transport & logistics | 2025 |
| Storm G Ltd | Professional & scientific | 2024 |
| Stortec Limited | Transport & logistics | 2025 |
| Storvue Limited | Real estate | 2026 |
| Storytellers Teesside Ltd | Hospitality | 2026 |
| Stowcross Limited | Construction | 1999 |
| Strategic Estates (Durham) Ltd | Extraterritorial | 2012 |
| Strategic Estates Ltd | Professional & scientific | 2011 |
| Strategic Sites Limited | Extraterritorial | 2006 |
| Studio ORA Ltd | Other services | 2025 |
| SU Lettings Limited | Real estate | 2021 |
| SU Medical Limited | Health & social care | 2013 |
| Sublime Aesthetics & Beauty Ltd | Other services | 2023 |
| Success Brew Limited | Professional & scientific | 2020 |
| Success First Limited | Professional & scientific | 2012 |
| Sumners Properties Ltd | Real estate | 2020 |
| Sumsco Ltd | Real estate | 2025 |
| Sun City Studio Limited | Other services | 2013 |
| Sundial Court Management Company Limited | Administrative & support | 1992 |
| Sunrise LIU Limited | Hospitality | 2021 |
| Supertyr Limited | Real estate | 2006 |
| Supreme Healthcare Solutions Ltd | Health & social care | 2018 |
| Supreme Steelwork Services Ltd | Manufacturing | 2023 |
| Sure Fit Property Developments Ltd | Real estate | 2024 |
| Suzanne Wilson Hair Limited | Other services | 2024 |
| SW Mawdesley Limited | Construction | 2015 |
| Swan Advanced Vehicle Operations Limited | Wholesale & retail | 2018 |
| Sweet & Greet Ltd | Wholesale & retail | 2021 |
| Symmetris Limited | Professional & scientific | 2012 |
| Synthonia Couriers and Travel Ltd | Transport & logistics | 2026 |
| T & E Access Ltd | Professional & scientific | 2025 |
| T & T O'Hara W P Ltd | Administrative & support | 2024 |
| T Leech Ltd | Administrative & support | 2024 |
| T Lwin WP Ltd | Administrative & support | 2024 |
| T4 Weeford Limited | Administrative & support | 2018 |
| Taae Limited | Real estate | 2009 |
| Talent Magpie Limited | Administrative & support | 2022 |
| TAN 360 Ltd | Wholesale & retail | 2019 |
| Taniya Properties Ltd | Real estate | 2011 |
| Tascomp Limited | Wholesale & retail | 1978 |
| Tasty Bites Hartlepool Limited | Hospitality | 2024 |
| Taylor Bowes Project Services Limited | Professional & scientific | 2012 |
| Taylor Design Services Ltd | Professional & scientific | 2024 |
| Taylor Family Partnership LLP | | 2021 |
| Taylored Properties Limited | Real estate | 2019 |
| Taylorepc Ltd | Construction | 2022 |
| Tbac (UK) Limited | Construction | 2013 |
| Teal Opal Ltd | Real estate | 2018 |
| Teamcl Limited | Arts & recreation | 2016 |
| Technical Construction Management Ltd | Professional & scientific | 2024 |
| Technical Polymers Consultancy Ltd | Professional & scientific | 2019 |
| Technicold Limited | Energy | 2022 |