| Seed Renewables Limited | Construction | 2013 |
| Seed Treating Services Limited | Professional & scientific | 2007 |
| Seeded Marketing Ltd | Professional & scientific | 2022 |
| Seedhive Ltd | Wholesale & retail | 2025 |
| Seekand Ltd | Information & communication | 2026 |
| Seekings Advisory Limited | Professional & scientific | 2021 |
| Seenue Ltd | Professional & scientific | 2017 |
| Sefa Consulting Ltd | Professional & scientific | 2023 |
| Segmentum Analysis Ltd | Information & communication | 2014 |
| Segpa Limited | Wholesale & retail | 2025 |
| Seirlis Ltd | Manufacturing | 2025 |
| Sejdijaj Engineering Consulting Limited | Professional & scientific | 2025 |
| Sekme Ltd | Transport & logistics | 2024 |
| Sekoa Limited | Real estate | 2017 |
| Sekoa Properties Limited | Real estate | 2025 |
| Selbys of Cambridge Ltd | Manufacturing | 2024 |
| Selead International Co., Ltd | Wholesale & retail | 2025 |
| Selebra Homecare Ltd | Health & social care | 2022 |
| Select Agency Services Limited | Administrative & support | 1995 |
| Select English Limited | Education | 1997 |
| Select Imports Ltd | Wholesale & retail | 2025 |
| Select Maintenance Group Limited | Construction | 2019 |
| Select Tutorial Services Limited | Financial services | 2021 |
| Selected Removals Ltd | Transport & logistics | 2023 |
| Selected Storage Ltd | Transport & logistics | 2024 |
| Selected Vehicle Hire Ltd | Administrative & support | 2026 |
| Selection Techniques Limited | Professional & scientific | 1960 |
| Selen Decoration Ltd | Construction | 2025 |
| Selenite Wellness Retreats Limited | Other services | 2019 |
| Selftown Limited | Households | 1983 |
| Selion Technologies Limited | Information & communication | 2023 |
| Seller Helper Ltd. | Professional & scientific | 2022 |
| Sellercentric Ltd | Wholesale & retail | 2024 |
| Selling 2 Humans Ltd | Professional & scientific | 2026 |
| Selling Solutions Cambridge Ltd | Professional & scientific | 2008 |
| Selvita Limited | Professional & scientific | 2015 |
| Semarion Ltd | Professional & scientific | 2018 |
| Semarts Utility Consulting Ltd | Professional & scientific | 2022 |
| Semikon Ltd | Extraterritorial | 2024 |
| Seminar Limited | Extraterritorial | 1990 |
| Semiyield AI Dienst Ltd | Professional & scientific | 2025 |
| Semizone Ltd | Wholesale & retail | 2026 |
| Semosan Limited | Wholesale & retail | 2019 |
| SEN Skin Limited | Health & social care | 2016 |
| Senate Holdings Ltd | Information & communication | 2019 |
| Senescence Care Ltd | Administrative & support | 2025 |
| Senesys BIO Limited | Professional & scientific | 2026 |
| Senior Trade Ltd | Wholesale & retail | 2023 |
| Senloda Ltd | Information & communication | 2025 |
| Senmarketing Digital Limited | Professional & scientific | 2021 |
| Senova Limited | Agriculture & fishing | 1981 |
| Sensense Ltd | Professional & scientific | 2022 |
| Sensize Limited | Information & communication | 2016 |
| Sensor Methods Limited | Professional & scientific | 2021 |
| Sensory Cambridge Ltd | Administrative & support | 2024 |
| Sensory Homes & Gardens Ltd | Construction | 2026 |
| Sentek Limited | Manufacturing | 1992 |
| Sentinel Oncology Limited | Professional & scientific | 2005 |
| Sentrilix Ltd | Information & communication | 2025 |
| Senvi Ltd | Real estate | 2015 |
| Seongwoo Trading Limited | Extraterritorial | 2018 |
| Sepura Holdings Limited | Financial services | 2022 |
| Sepura Limited | Professional & scientific | 2002 |
| Sepura Overseas Limited | Professional & scientific | 2012 |
| Sequoia International Media Co., Ltd | Information & communication | 2025 |
| Seraphus Limited | Professional & scientific | 2009 |
| Serena Jewellery Ltd | Manufacturing | 2009 |
| Serenatis BIO Limited | Professional & scientific | 2024 |
| Serene Private Limited | Wholesale & retail | 2020 |
| Serenity Accommodation Manchester Ltd | Hospitality | 2019 |
| Serera Limited | Construction | 2022 |
| Serjoga Safonov Ltd | Manufacturing | 2022 |
| Serotonin Films Limited | Information & communication | 2007 |
| Serpentine Estates LLP | | 2010 |
| Serpentine Sushi Limited | Hospitality | 2024 |
| Serrao Halim Limited | Professional & scientific | 2024 |
| Servante Limited | Professional & scientific | 2021 |
| Service of Mankind Mission Ltd | Health & social care | 2020 |
| Services Machinery & Trucks Ltd | Wholesale & retail | 2017 |
| Sesu Grill Limited | Hospitality | 2025 |
| Seti Classes Ltd | Education | 2024 |
| Settlesmart Global Ltd | Education | 2025 |
| Settr AI Ltd | Information & communication | 2025 |
| SEU Contracting Limited | Professional & scientific | 2019 |
| Sevani Consulting Ltd | Manufacturing | 2025 |
| Seven Acres Development Limited | Households | 2012 |
| Seven Flower Ltd | Arts & recreation | 2024 |
| Sevennation Decorating Ltd | Construction | 2020 |
| Seventh Rochford (Slough) Management Company Limited | Households | 1981 |
| Severn Thermal Solutions Limited | Manufacturing | 2006 |
| Sevrank Limited | Information & communication | 2026 |
| SEW Knit Craft Ltd. | Wholesale & retail | 2013 |
| Sewell Residential Ltd | Real estate | 2019 |
| Sewingjustnow Limited | Manufacturing | 2025 |
| Seymour Davies Ltd. | Professional & scientific | 2002 |
| Seymour Joy Limited | Agriculture & fishing | 1991 |
| SF Asset Advisory Limited | Professional & scientific | 2018 |
| SF Mortgages Limited | Financial services | 2015 |
| SFB Carpentry and Building Limited | Construction | 2007 |
| SFH Property Limited | Construction | 2025 |