| Rosey Properties Essex Limited | Real estate | 2026 |
| RT Heating Solutions Ltd | Construction | 2024 |
| Ruby Fire Limited | Construction | 2014 |
| S a S Properties (Essex) Ltd | Real estate | 2026 |
| S Warburton Electrical Ltd | Construction | 2024 |
| S&B Outdoor Living Ltd | Administrative & support | 2026 |
| S.G.N Trading UK Division Ltd | Wholesale & retail | 2022 |
| SAG Traders UK Ltd | Wholesale & retail | 2026 |
| Sailkote Plus UK Ltd | Other services | 2011 |
| Sams Wine Bar Harwich Ltd | Hospitality | 2026 |
| Sarah Enterprise DC Ltd | Other services | 2025 |
| Sari Lata Ltd | Real estate | 2026 |
| SCD Services Ltd | Construction | 2022 |
| SCH Transport Ltd | Transport & logistics | 2021 |
| Scrappi Productions Ltd | Information & communication | 2026 |
| SDB Signalling Limited | Construction | 2017 |
| Sequel Build Limited | Information & communication | 2015 |
| SGN Professionals Ltd | Administrative & support | 2022 |
| Shac Enterprises Ltd | Other services | 2018 |
| Shamrock 1924 RTM Company Ltd | Households | 2018 |
| Sigtek Ltd | Education | 2015 |
| Silent Protection Services Ltd | Administrative & support | 2024 |
| Silva Forma Ltd | Manufacturing | 2026 |
| Silver Cloud HR Limited | Professional & scientific | 2009 |
| Silverdex IT Limited | Information & communication | 2010 |
| SIX Magpies Consulting Ltd | Professional & scientific | 2020 |
| Sky-Ri Construction Ltd | Construction | 2026 |
| Sky-Ri Holdings Ltd | Real estate | 2022 |
| Sky-Ri Projects Ltd | Professional & scientific | 2025 |
| Slaget Theatre Ltd | Arts & recreation | 2022 |
| Sleepless Recordings Limited | Information & communication | 2019 |
| SM Executive Services Limited | Professional & scientific | 2023 |
| Smooth Construction Limited | Construction | 2023 |
| Smurf Ltd | Transport & logistics | 2025 |
| Soluli Ltd | Construction | 2013 |
| SOS Wrestling Ltd | Arts & recreation | 2023 |
| Spearske Limited | Hospitality | 2025 |
| Spillame Ltd | Wholesale & retail | 2023 |
| Sscg Property Ltd | Construction | 2025 |
| SSL Tanning Ltd | Wholesale & retail | 2024 |
| Ssoc Ltd | Manufacturing | 2024 |
| Steel Design Build Limited | Manufacturing | 2019 |
| Steer Ahead Ltd | Other services | 2011 |
| Stefano Services Ltd | Transport & logistics | 2025 |
| Steiner Herbert Group Ltd | Financial services | 2023 |
| Steiner Herbert Personnel Services Ltd | Administrative & support | 2011 |
| Steiner Herbert Property Services Ltd | Real estate | 2023 |
| Stochastic Financial Modelling Ltd | Financial services | 2001 |
| Strength and Honour Gym Ltd | Arts & recreation | 2021 |
| Stuart Henshall Ltd | Administrative & support | 2025 |
| Suffolk Dredging LLP | | 2025 |
| Summer 26 Pubs Limited | Hospitality | 2026 |
| Sunburst Property Ltd | Real estate | 2024 |
| Surya Capital Limited | Manufacturing | 1994 |
| Surya Foods Limited | Financial services | 2020 |
| Surya Hotels Limited | Hospitality | 2010 |
| Surya Solar Limited | Construction | 2010 |
| Swedish Asset Finance Limited | Financial services | 2021 |
| Sycamore Lodge Consultancy Ltd | Professional & scientific | 2023 |
| T & L Surveying Limited | Construction | 2013 |
| T Mark Limited | Construction | 2016 |
| T R M Surveying Limited | Construction | 2016 |
| T Sutton Services Limited | Construction | 2025 |
| T'S Sports Bar Limited | Arts & recreation | 2026 |
| Tanstaafl Limited | Real estate | 2017 |
| Taylors Enterprise TM Ltd | Construction | 2024 |
| Teen Talk (Harwich) | Health & social care | 2011 |
| TEN HUT Limited | Construction | 2016 |
| Tendring Darts Ltd | Wholesale & retail | 2025 |
| Tendring Farm Cluster CIC | Professional & scientific | 2024 |
| Tendring Garden Services Ltd | Administrative & support | 2023 |
| Terralytics Consulting Limited | Professional & scientific | 2025 |
| TEY Tours Limited | Transport & logistics | 2024 |
| THE Admirals (Nelson Road) Limited | Households | 2019 |
| THE Best Harwich Hand Car Wash Ltd | Wholesale & retail | 2024 |
| THE Business Finance Consultancy Limited | Professional & scientific | 2026 |
| THE Confident Company Business Coaching Ltd | Professional & scientific | 2025 |
| THE Discount Store 200 Ltd | Wholesale & retail | 2025 |
| THE Hair & Beauty BAR466 Ltd | Other services | 2015 |
| THE Horse Rangers Association (Harwich) Limited | Agriculture & fishing | 2003 |
| THE Inventory Shop Ltd | Administrative & support | 2024 |
| THE Lighthouse Sports and Social Hub Essex Limited | Arts & recreation | 2018 |
| THE Luxe Travel Concierge Limited | Administrative & support | 2026 |
| THE Mariners (Dovercourt) Management Limited | Households | 2000 |
| THE Muse Academy of Dance Harwich Ltd | Arts & recreation | 2025 |
| THE New Martin Lutheran Movement Limited | Professional & scientific | 2024 |
| THE Old Courthouse Inn Limited | Hospitality | 2014 |
| THE Snug Play Cafe Ltd | Hospitality | 2024 |
| THE Soteria Group Ltd | Education | 2023 |
| THE Tendring Osteopathic and Wellness Clinic Ltd | Health & social care | 2023 |
| THE Trafalgar Dovercourt Limited | Hospitality | 2021 |
| THE Ultimate Makeover Ltd | Education | 2020 |
| THE Waterfront (Dovercourt) Ltd | Hospitality | 2016 |
| Thomas Campbell Limited | Other services | 2003 |
| Thompson Cooper Limited | Administrative & support | 1973 |
| Timeline Auctions Ltd | Administrative & support | 2009 |
| Tippeetap Limited | Administrative & support | 2020 |
| TJ Cheverall Limited | Transport & logistics | 2019 |
| TLJ Education Consultancy Ltd | Education | 2017 |
| Tober Surveying Solutions Ltd | Administrative & support | 2016 |