| R J Green Building Contractors Limited | Construction | 2017 |
| R Safety Limited | Construction | 2014 |
| RB Security Services (Rbss) Ltd | Administrative & support | 2020 |
| Re-Search North East CIC | Education | 2025 |
| Reality Studios Limited | Arts & recreation | 2010 |
| Redwood Sports Marketing Limited | Professional & scientific | 2012 |
| Reed Agri Services Ltd | Agriculture & fishing | 2020 |
| Reillec Limited | Real estate | 2018 |
| Repc Consulting Ltd | Information & communication | 2010 |
| Rest Easy Stays Ltd | Hospitality | 2024 |
| Retail Organisation Limited | Professional & scientific | 1991 |
| Retrouver Ltd | Administrative & support | 2012 |
| Rigel Partners Limited | Administrative & support | 2025 |
| Rise Artisan Limited | Hospitality | 2018 |
| RLW Properties Limited | Construction | 2003 |
| Robert Tiplady Limited | Agriculture & fishing | 2003 |
| Rockbourne Consultancy Services Ltd | Professional & scientific | 2023 |
| Rodriguez Builders Limited | Construction | 2005 |
| Roundhouse Building Solutions (Holdings) Limited | Financial services | 2015 |
| Route Rise Media Limited | Professional & scientific | 2025 |
| RST Installations Ltd | Construction | 2020 |
| Rubilah Ltd | Wholesale & retail | 2019 |
| Rumulus Limited | Wholesale & retail | 2019 |
| Rushlift Mechanical Handling Ltd | Manufacturing | 2019 |
| RVM Global Ltd | Professional & scientific | 2026 |
| S J Deli Cafe Limited | Wholesale & retail | 2024 |
| S Warwick Ltd | Construction | 2015 |
| S&A Builders Merchants (Holdings) Limited | Financial services | 2015 |
| S&A Fabrications (Holdings) Limited | Financial services | 2015 |
| S&A Fabrications Limited | Manufacturing | 2015 |
| S&S Projects - Teesdale Ltd | Construction | 2018 |
| S&S Property & Development Ltd | Real estate | 2023 |
| S&S Taverns Ltd | Hospitality | 2025 |
| S.M. QC Services Ltd | Professional & scientific | 2026 |
| Sabey Brothers Ltd | Real estate | 2026 |
| Safesoles Ltd | Real estate | 2003 |
| Saldanha Taxation Limited | Professional & scientific | 2013 |
| Salt to City Stays Ltd | Real estate | 2025 |
| Salus Street Limited | Construction | 2020 |
| SAM Gibbons Interiors Ltd | Professional & scientific | 2025 |
| Sandersea Limited | Education | 2021 |
| Sarah Haymes Consulting Limited | Professional & scientific | 2024 |
| Sarah Last School of Motoring Limited | Education | 2021 |
| Sayer Hill 1959 Limited | Extraterritorial | 2014 |
| Scenic Air Tours North East Ltd | Education | 2017 |
| Scops Associates Limited | Professional & scientific | 2021 |
| Scott Hammond Roofing Services Limited | Construction | 2009 |
| SDA Properties Limited | Real estate | 2003 |
| SDB Construction (North East) Ltd | Construction | 2021 |
| Secureemax Ltd | Manufacturing | 2022 |
| Sentinel Property Development Limited | Real estate | 2019 |
| Seven Minute Mind Care Limited | Health & social care | 2024 |
| Sherlockmp Barnard Castle Ltd | Financial services | 2021 |
| Shevill Construction Ltd | Construction | 2025 |
| Sierra Charlie Foxtrot Ltd | Professional & scientific | 2013 |
| Simon Copeland Ltd | Administrative & support | 2013 |
| Simon Harvey Photography Ltd | Professional & scientific | 2011 |
| Simon's Butchers Limited | Wholesale & retail | 2022 |
| Sinful Sweets by Amanda Ltd | Manufacturing | 2025 |
| Siriwa Limited | Real estate | 2021 |
| SIX White Clouds Ltd | Professional & scientific | 2011 |
| Snow Slopes Ltd | Extraterritorial | 2011 |
| Socialbutterflyagency Ltd | Professional & scientific | 2024 |
| Southside Barber Studios Limited | Other services | 2024 |
| Specialist Plant Services Limited | Construction | 2012 |
| Speedbrand Limited | Real estate | 1986 |
| Spiffymap Ltd | Information & communication | 2008 |
| Sports and Sporting Limited | Wholesale & retail | 2014 |
| Spot-Kicks Ltd | Arts & recreation | 2024 |
| SPV Gabriel Limited | Other services | 2024 |
| ST. Mary's Close (Barnard Castle) Residents Association Limited | Households | 1992 |
| Stables Cafe Limited | Hospitality | 2024 |
| Star Cobblers & Key Cutters Limited | Other services | 2025 |
| Station Cottages Residents Association Limited | Households | 2023 |
| Stephen Clennell Services Limited | Wholesale & retail | 2007 |
| Stephen James Associates Limited | Financial services | 2004 |
| Stephenson Commercials Ltd | Wholesale & retail | 2024 |
| Stephenson Transport Logistics Ltd | Transport & logistics | 2024 |
| Steve Messam Studio Ltd | Arts & recreation | 2023 |
| Stockton & Darlington Railway Ltd | Wholesale & retail | 2018 |
| Stokell Howitt Investment Retail Ltd | Wholesale & retail | 2012 |
| Stonely and Sons Ltd | Administrative & support | 2016 |
| Stubbs Farming Limited | Agriculture & fishing | 1999 |
| SUE Hogg @ Dermasmooth Ltd | Other services | 2016 |
| Sue's Cafe Teesdale Limited | Hospitality | 2003 |
| Summer LEA Management Company Limited | Real estate | 2008 |
| Summit Finance (UK) Ltd | Financial services | 2009 |
| Support Solutions (UK) Ltd | Other services | 2014 |
| Surdev Limited | Hospitality | 1997 |
| Susan M Thwaite Limited | Professional & scientific | 2003 |
| Swaledale Sheep Breeder's Association | Agriculture & fishing | 1922 |
| Swinbank Bespoke Ltd | Construction | 2023 |
| Swinbank Properties Ltd | Real estate | 2023 |
| T F L Ltd | Administrative & support | 2024 |
| T.J.K Group Ltd | Administrative & support | 2024 |
| Taitte Co Limited | Arts & recreation | 2022 |
| Tallentire Real Estate Ltd | Real estate | 2021 |
| Tarns Electrical Ltd | Construction | 2018 |
| Tarns Holdings Ltd | Financial services | 2026 |
| Tarns Ventures Limited | Real estate | 2022 |