| SQ1 Groundworks Ltd | Construction | 2025 |
| SQ1 Projects Ltd | Construction | 2014 |
| Square Air Ltd | Hospitality | 2025 |
| Square Eyecare Limited | Health & social care | 2006 |
| Square Pizza (South END) Ltd | Hospitality | 2019 |
| Square Pizza City Limited | Hospitality | 2023 |
| Squarelux Limited | Real estate | 2017 |
| Squiggle (TM) Limited | Professional & scientific | 2016 |
| Squiggle Earth Limited | Professional & scientific | 2016 |
| Squiggle Glass Ltd | Wholesale & retail | 2010 |
| Squire & Sons Maintenance Limited | Construction | 2020 |
| Srisai Medical Limited | Health & social care | 2024 |
| SS Building and Property Maintenance Ltd | Real estate | 2026 |
| SS Complete Cleaning Services Ltd | Administrative & support | 2022 |
| SS Pro QS Services Ltd | Construction | 2012 |
| SS1 2NW Ltd | Real estate | 2005 |
| SS2 Post Production Ltd | Information & communication | 2025 |
| SS2 Recording Limited | Information & communication | 2019 |
| SS9 Design & Build Ltd | Construction | 2023 |
| Ssaonlineservices Ltd | Wholesale & retail | 2024 |
| SSC Partnership Limited | Professional & scientific | 2016 |
| SSF Transport Limited | Administrative & support | 2016 |
| ST Edmunds Community Association Ltd | Health & social care | 2006 |
| ST James Park (Parcel G) Management Company Limited | Households | 2023 |
| ST James Park (Parcels B and C) Management Company Limited | Households | 2022 |
| ST Lukes Serviced Accomodation Ltd | Hospitality | 2024 |
| ST Martins Massive RTM Company Limited | Extraterritorial | 2025 |
| ST Mortgage Solutions Ltd | Financial services | 2021 |
| Stablenote Ltd | Financial services | 2024 |
| Stacksmiths Agency Ltd | Information & communication | 2026 |
| Staff & Staff Personnel Consultants Ltd | Administrative & support | 2011 |
| Stag by Jamal Ltd | Wholesale & retail | 2025 |
| Stainless Equipment Company (Metal Finishers) Limited | Water & waste | 2006 |
| Stallion Stimulager Limited | Wholesale & retail | 2024 |
| Stambridge Holdings Limited | Financial services | 2025 |
| Stambridge Investments Limited | Real estate | 2021 |
| Stambridge Training Limited | Education | 2015 |
| Standhope Freehold Properties Limited | Extraterritorial | 1945 |
| Stanley N. Evans (Estates) Limited | Real estate | 1987 |
| Stanley Road Properties Limited | Real estate | 2001 |
| Stanley-Wills Ltd | Other services | 2022 |
| Stanton Rolls Limited | Real estate | 1978 |
| Star Amusements Limited | Arts & recreation | 1995 |
| Star Management Facilities COM Limited | Administrative & support | 2022 |
| Star PUB Company Limited | Hospitality | 2022 |
| Stark Salon Limited | Other services | 2012 |
| Starkish Property Group Limited | Real estate | 2017 |
| Starkish Relocations Ltd | Hospitality | 2019 |
| Starkish UK Limited | Wholesale & retail | 2017 |
| Starview Management Ltd | Real estate | 2023 |
| Station Garage (Southend) Ltd | Wholesale & retail | 2015 |
| Station News Brentwood Limited | Wholesale & retail | 2015 |
| Station Road Essex Ltd | Real estate | 2025 |
| Status PM Limited | Professional & scientific | 2012 |
| Stave House Limited | Education | 2013 |
| Steel Fabrications UK Limited | Manufacturing | 2020 |
| Steelustrial Ltd | Other services | 2025 |
| Steeple Gate Management Company Limited | Households | 2006 |
| Stemss Group Ltd | Information & communication | 2024 |
| Stephanie Bouquet Limited | Manufacturing | 2018 |
| Stephens Rickard Ltd | Administrative & support | 2013 |
| Stephowe Limited | Hospitality | 2025 |
| Stephs Beachside Aromas Limited | Wholesale & retail | 2025 |
| Steps Ahead Arts in Education Limited | Education | 2004 |
| Steps Ahead Life CIC | Education | 2021 |
| Stepsin Care and Support Services Limited | Health & social care | 2013 |
| Sterling Private Finance Ltd | Financial services | 2023 |
| Sterling Street Capital Limited | Financial services | 2025 |
| Stern Close RTM Company Limited | Households | 2011 |
| Steve Ruston Builders Ltd | Construction | 2005 |
| Steve Ruston Ltd | Administrative & support | 2017 |
| Stevenson Publications Limited | Other services | 1989 |
| Stewart Pink Limited | Professional & scientific | 2023 |
| Stewarts Reach and Wolds View Residential Management Company Limited | Households | 2024 |
| Stibbards Denture Clinic Ltd | Manufacturing | 2025 |
| Stillwell Holdings Limited | Financial services | 2021 |
| Stillwell Studio Ltd | Information & communication | 2025 |
| Stitch & Sole Limited | Wholesale & retail | 2026 |
| STL Music Limited | Administrative & support | 2012 |
| Stock Utilities Limited | Manufacturing | 2004 |
| Stoked Vegan Ltd | Hospitality | 2020 |
| Stone Bridge Frames Ltd | Wholesale & retail | 2026 |
| Stone Shield Ltd | Construction | 2023 |
| Stone Spot Limited | Wholesale & retail | 2025 |
| Stone Wilson Limited | Professional & scientific | 2023 |
| Storangle Ltd | Wholesale & retail | 2022 |
| Storey Books Limited | Professional & scientific | 2013 |
| Stork Finance Limited | Professional & scientific | 2019 |
| Stormblue Limited | Hospitality | 2019 |
| Stornoway 1973 Limited | Extraterritorial | 2013 |
| Stortford Fields (Bishops Stortford) Management Company Limited | Households | 2018 |
| Stortford Fields 2 (Bishop Stortford) Management Company Limited | Households | 2024 |
| Storyverse AI Studio Ltd | Information & communication | 2026 |
| Stowe Court RTM Company Limited | Households | 2021 |
| Straight Line Resourcing Limited | Construction | 2016 |
| Stratagem Consultancy Limited | Professional & scientific | 2019 |
| Strategic Financial Planning Ltd. | Financial services | 2002 |
| Strategic IFA Ltd | Financial services | 2004 |
| Strategic Resolutions Limited | Other services | 2024 |
| Strategic Software Limited | Information & communication | 2012 |