| Sheet Plant Consultants Limited | Professional & scientific | 2020 |
| Shield Care Ltd | Health & social care | 2017 |
| Shivansh N C Ltd | Health & social care | 2020 |
| Showblock Group Ltd | Financial services | 2022 |
| Showblock Ltd | Professional & scientific | 2013 |
| Showcase Studios Group Ltd | Other services | 2020 |
| SI Aviation Services Limited | Transport & logistics | 2017 |
| SI Workspaces Ltd | Real estate | 2026 |
| Sidereus Ltd | Information & communication | 2021 |
| Signature Construction (ST Ives) Limited | Construction | 2021 |
| Silent Marketing Ltd. | Information & communication | 2020 |
| Silicon Cortex Limited | Professional & scientific | 2015 |
| Silogic Technology Limited | Professional & scientific | 2022 |
| Silvest Ltd | Wholesale & retail | 2018 |
| Simon Boon Homes (Ryhall) Ltd | Construction | 2023 |
| Simon Boon Homes Limited | Construction | 2010 |
| Simpsons Incorporated Limited | Financial services | 2017 |
| Simpsons Lakeside Properties Limited | Real estate | 2017 |
| Simulation Services Limited | Professional & scientific | 2019 |
| Singh Transport Services Ltd | Transport & logistics | 2020 |
| Sipro Community Hub CIC | Other services | 2024 |
| Sizana Limited | Wholesale & retail | 2016 |
| SJH Pubs Ltd | Hospitality | 2025 |
| SJM Asset Management Limited | Financial services | 2020 |
| Skydive Instruction Limited | Arts & recreation | 2010 |
| Skyshield Systems Limited | Extraterritorial | 2008 |
| Slepe Hall Hotel Ltd | Hospitality | 2020 |
| Smartmars Ltd | Real estate | 2024 |
| Smile Travel Limited | Administrative & support | 2020 |
| Smith Architects Ltd | Professional & scientific | 2022 |
| Smith Roberts Training Services Limited | Education | 2018 |
| SMR Roofing Ltd | Construction | 2025 |
| Snub Pools Limited | Construction | 2025 |
| SO Kleen Cleaning and Gardening Ltd | Administrative & support | 2025 |
| SO Protected Holdings Ltd | Financial services | 2025 |
| Soham Fitness & Business Centre Limited | Arts & recreation | 2024 |
| Soham Fitness Limited | Education | 2025 |
| Solar Energy Cambridge Ltd | Other services | 2022 |
| Solon & Co Limited | Professional & scientific | 2012 |
| Soopa Doopa Branding Limited | Other services | 2011 |
| Soopa Doopa Gifts Limited | Other services | 2012 |
| Soopa Doopa Properties Limited | Real estate | 2020 |
| Soundio Ltd | Extraterritorial | 2024 |
| Source Kitchen Restaurants Limited | Hospitality | 2022 |
| South Coast Furnishing (Residential) Limited | Real estate | 2012 |
| South Coast Furnishing (Southampton) Limited | Real estate | 2012 |
| South Coast Furnishing Company Limited | Real estate | 1951 |
| Spartan Recruitment Ltd | Administrative & support | 2023 |
| Spcl Group Limited | Financial services | 2026 |
| Spcl Property Limited | Real estate | 2026 |
| Speed Alloys Holdings Limited | Real estate | 2024 |
| Spider EYE Productions Limited | Information & communication | 1999 |
| Sport Memorial's Limited | Other services | 2025 |
| Sports Gear and Wear Limited | Wholesale & retail | 2019 |
| Spotfix Ltd | Administrative & support | 2024 |
| Sprachmeisterin Limited | Other services | 2024 |
| Spray DEC Ltd | Construction | 2025 |
| SPW Consultants Limited | Professional & scientific | 2012 |
| SQ Roots Build Limited | Professional & scientific | 2020 |
| SQ Roots Design Limited | Professional & scientific | 2020 |
| SQ Roots Residence Ltd | Professional & scientific | 2020 |
| SRM Electrical Services Ltd | Construction | 2024 |
| ST IA Silver Ltd | Wholesale & retail | 2002 |
| ST Ives (Hunts) Golf Club Limited | Hospitality | 2019 |
| ST Ives Art Limited | Wholesale & retail | 2023 |
| ST Ives Art School Limited | Education | 2022 |
| ST Ives BID Ltd | Financial services | 2013 |
| ST Ives Bikes Limited | Wholesale & retail | 2020 |
| ST Ives Bookkeeping Ltd | Professional & scientific | 2025 |
| ST Ives BUS Co Ltd | Transport & logistics | 2004 |
| ST Ives Chocolate Ltd | Wholesale & retail | 2025 |
| ST Ives Cookery School Ltd | Hospitality | 2023 |
| ST Ives DRY Cleaning Limited | Other services | 2022 |
| ST Ives Festivals CIC | Hospitality | 2020 |
| ST Ives GAS Services Limited | Other services | 2014 |
| ST Ives Kayal & SUP Hire Ltd | Administrative & support | 2024 |
| ST Ives Meat Limited | Wholesale & retail | 2017 |
| ST Ives Red Self Drive Boat Hire Ltd | Administrative & support | 2024 |
| ST Ives Riverside Management Company Limited | Households | 2022 |
| ST Ives Rugby Union Football Club Limited | Arts & recreation | 2012 |
| ST Ives School of Painting Ltd | Education | 2022 |
| ST Ives Services Ltd | Information & communication | 2025 |
| ST Ives Shop Limited | Wholesale & retail | 2025 |
| ST Ives Society of Artists Ltd | Wholesale & retail | 2009 |
| ST Ives Techie Ltd | Wholesale & retail | 2021 |
| ST Ives Town FC Limited | Arts & recreation | 2019 |
| ST Ives Town FC Sports Complex Limited | Arts & recreation | 2021 |
| ST Ives Trading Ltd | Wholesale & retail | 2023 |
| ST Ives Window Cleaning Limited | Administrative & support | 2020 |
| ST Ives Yellow Self Drive Boat Hire Ltd | Administrative & support | 2024 |
| ST. Ives Engine Services Ltd. | Wholesale & retail | 2003 |
| ST. Ives Motors (Hunts) Limited | Wholesale & retail | 1956 |
| ST. Ives PCN Limited | Health & social care | 2024 |
| ST. Ives Performance Tyres Ltd. | Wholesale & retail | 2010 |
| ST. Ives Quickprint Limited | Other services | 2006 |
| ST. Ives Scaffolding Limited | Construction | 2016 |
| ST. Ives Scaffolding Solutions Limited | Construction | 2016 |
| ST. Ives Signs Ltd | Manufacturing | 2025 |
| Stadium Solutions (UK) Limited | Manufacturing | 2018 |
| Stafflyft Limited | Information & communication | 2023 |