| S Dixon Flooring Limited | Wholesale & retail | 2021 |
| S Hughes Automation Limited | Administrative & support | 2014 |
| S J P Financial Services Ltd | Financial services | 2006 |
| S K P Management Limited | Real estate | 2008 |
| S Lord Holdings Limited | Financial services | 2022 |
| S&C Building UK Limited | Construction | 2025 |
| S&C Home Improvements Ltd | Construction | 2020 |
| S.A.S JET Wash Services Limited | Water & waste | 2021 |
| S.C Heating and Plumbing Ltd | Construction | 2022 |
| S.Round Equestrian Ltd | Agriculture & fishing | 2019 |
| S2N Limited | Administrative & support | 2024 |
| Safe Hands VIP Club Ltd | Financial services | 2022 |
| Safechem Limited | Wholesale & retail | 1986 |
| Safeguard Call Handling Services Ltd | Administrative & support | 2014 |
| Safeguard Facilities Management Limited | Administrative & support | 2013 |
| Safeguard Group of Companies Ltd | Professional & scientific | 2015 |
| Safeguard Home Care Ltd | Households | 2020 |
| Safeguard Security (NE) Limited | Administrative & support | 2012 |
| Sage Wealth Management Limited | Financial services | 2010 |
| Sajaka LLP | | 2017 |
| Sakura KOI Limited | Professional & scientific | 2010 |
| SAM Hughes Music Company Ltd | Arts & recreation | 2025 |
| SAM Top Fade Ltd | Other services | 2026 |
| Sambuca Chelest Limited | Hospitality | 2019 |
| Sampson Print Limited | Manufacturing | 2009 |
| Sandersons Properties Ltd | Real estate | 2025 |
| Sandmartins Property Ltd | Real estate | 2025 |
| Sandringham Financial Solutions Limited | Professional & scientific | 2022 |
| Sarahs Deli Limited | Hospitality | 2019 |
| SAS Joinery & Building Limited | Construction | 2023 |
| SB & Sons Properties Limited | Real estate | 2024 |
| SCG Retail Services Ltd | Wholesale & retail | 2020 |
| Schooltripmaster Ltd | Education | 2025 |
| Sciator Services Ltd | Administrative & support | 2016 |
| Scott Church Offshore Management Services Ltd | Professional & scientific | 2023 |
| Scottittravel Limited | Information & communication | 2025 |
| Scott’S Escapes Ltd | Real estate | 2025 |
| Scrap the Mask Collective Limited | Other services | 2026 |
| Scrimger & Oakes Limited | Financial services | 2017 |
| Scruffy Urchin Ltd | Arts & recreation | 2013 |
| Scuba Diver Training Ltd | Arts & recreation | 2019 |
| SD Industrial Cleaning Ltd | Administrative & support | 2026 |
| SD Surveys Limited | Professional & scientific | 2014 |
| Seal Tech Northeast Limited | Construction | 2025 |
| Seddco Ltd | Wholesale & retail | 2019 |
| Selvro Ltd | Information & communication | 2026 |
| Sendai Ltd | Education | 2023 |
| Sensory Pathways CIC | Education | 2025 |
| Sentaford Limited | Administrative & support | 2003 |
| SF Partners Group Ltd | Hospitality | 2024 |
| SF Utilities (NE) Limited | Construction | 2020 |
| SG Fabrications (North East) Ltd | Manufacturing | 2008 |
| SGS Property Development Limited | Construction | 2016 |
| Shaun Stokoe Electrical Services Limited | Construction | 2000 |
| Shaunamae Limited | Arts & recreation | 2024 |
| Shincliffe Consultancy Limited | Wholesale & retail | 2009 |
| Shincliffe Mill Nursery Ltd | Wholesale & retail | 2022 |
| Shipmove Ltd | Professional & scientific | 2015 |
| SHS Financial Services Ltd | Financial services | 2024 |
| Sidestep Systems Limited | Administrative & support | 2016 |
| Signtech (UK) Limited | Manufacturing | 2009 |
| Silverglen Support Services Ltd | Administrative & support | 2013 |
| SIM Desserts Ltd | Hospitality | 2023 |
| Sim-Plify (NE) Ltd | Information & communication | 2021 |
| Simply DKS Ltd | Wholesale & retail | 2020 |
| Simply SCM Ltd | Other services | 2023 |
| Simply YOU Beauty (NE) Limited | Other services | 2023 |
| Sjfoto and Broadcast Limited | Information & communication | 2008 |
| SJJ Business and Financial Consultancy Limited | Professional & scientific | 2025 |
| SK Panel & Paint Limited | Wholesale & retail | 2011 |
| Skts Group Limited | Administrative & support | 2023 |
| Skyerockett Limited | Real estate | 2023 |
| Skyline Roofs North Ltd | Wholesale & retail | 2021 |
| SLB Mining Solutions UK Ltd | Wholesale & retail | 2025 |
| Slepagnow Ltd | Wholesale & retail | 2026 |
| SLP Developments Limited | Construction | 2007 |
| Sm'Ashburger Seaham Harbour Ltd | Hospitality | 2022 |
| Sm'Ashleys Ltd | Hospitality | 2023 |
| Smajp Ltd | Hospitality | 2025 |
| Smart Bodies North East Ltd | Wholesale & retail | 2024 |
| Smart North East Entertainment Limited | Administrative & support | 2024 |
| Smart Property Services (NE) Limited | Construction | 2022 |
| Smartech Facilities Management Ltd | Professional & scientific | 2023 |
| Smarter Surveying Systemz Limited | Water & waste | 2026 |
| Smartsheald Security Services Limited | Manufacturing | 2014 |
| Smelf Property Ltd | Real estate | 2024 |
| SMJ Civils Ltd | Construction | 2022 |
| Smjd Properties Ltd | Real estate | 2025 |
| SMY Medical Ltd | Health & social care | 2023 |
| Snice Partners Ltd | Real estate | 2019 |
| Snice Rent Limited | Real estate | 2018 |
| Snice SA Limited | Real estate | 2022 |
| SNO Services UK Ltd | Transport & logistics | 2021 |
| Snuffy and Co Ltd | Manufacturing | 2021 |
| Social Harmony CIC | Public administration | 2024 |
| Sofa and Chair by Middleton Ltd | Manufacturing | 2026 |
| Sofabros Ltd | Wholesale & retail | 2026 |
| Somnath Trading Ltd | Construction | 2016 |
| Sortcode Processing Limited | Professional & scientific | 2015 |
| Source Vintage Limited | Wholesale & retail | 2024 |