| Swaay Technologies Limited | Administrative & support | 2026 |
| Swaffer Limited | Wholesale & retail | 2016 |
| Swam Media Services Limited | Professional & scientific | 2016 |
| Swan Court (Cygnet Park) Management Company Limited | Real estate | 2003 |
| Swan Inn Property Management Limited | Construction | 2025 |
| Swan Logistics Ltd | Transport & logistics | 2026 |
| Swan Motors Ltd | Wholesale & retail | 2019 |
| Swangord Welding and Fabrication Ltd | Manufacturing | 2018 |
| Swanton Morley Residents Management Company Limited | Other services | 2024 |
| Swastik Store Ltd | Wholesale & retail | 2024 |
| SWB Electrical Services (UK) Ltd | Construction | 2014 |
| Sweet Ideas Limited | Wholesale & retail | 1997 |
| Sweetlife Digital Ltd | Information & communication | 2025 |
| Sweetmore Construction Limited | Construction | 2015 |
| Sweets Clouds Ltd | Wholesale & retail | 2025 |
| Sweetvine Properties Limited | Other services | 2004 |
| Swerish Associates Ltd | Financial services | 2022 |
| Swift Car Care Holdings Ltd | Financial services | 2021 |
| Swift Car Care Services Limited | Wholesale & retail | 1991 |
| Swift Carz Limited | Transport & logistics | 2004 |
| Swift Communications Ltd | Information & communication | 2016 |
| Swift Electrical Solutions (Northants) Limited | Construction | 2013 |
| Swift Fire and Safety Limited | Administrative & support | 2019 |
| Swift Handy Ltd | Professional & scientific | 2023 |
| Swift Instruments Ltd | Other services | 2015 |
| Swift Properties (Peterborough) Ltd | Real estate | 2023 |
| Swift Transport and Haulage Ltd | Transport & logistics | 2018 |
| Swift Transport Services 24/7 Ltd | Transport & logistics | 2022 |
| Swiftbrit Logistics Ltd | Transport & logistics | 2026 |
| Swiftcare Carpets Ltd | Wholesale & retail | 2023 |
| Swiftcomm Holdings Ltd | Financial services | 2025 |
| Swihp Ltd | Information & communication | 2025 |
| Swimex Limited | Administrative & support | 2005 |
| Swing Driver Ltd | Transport & logistics | 2020 |
| Swisschris Limited | Real estate | 2026 |
| Switch Commercial Investments Limited | Real estate | 2020 |
| Switch Electrical Wholesale Limited | Wholesale & retail | 2009 |
| Switch Holdings Limited | Financial services | 2021 |
| Switch Safe Ltd | Manufacturing | 2020 |
| SX Vision Ltd | Information & communication | 2004 |
| SXM Ltd | Transport & logistics | 2015 |
| SXM Trans Ltd | Transport & logistics | 2026 |
| SY Property Holdings Ltd | Real estate | 2025 |
| Sycamore (Peterborough) Limited | Wholesale & retail | 1926 |
| Sycamore (Stamford) Limited | Wholesale & retail | 1935 |
| Sycamore Motorcycles (Witham) Limited | Wholesale & retail | 2022 |
| Sycamore Motorcycles Limited | Wholesale & retail | 2019 |
| Syed Spiritual Retreats Ltd | Administrative & support | 2022 |
| SYED114 Tradings Ltd | Transport & logistics | 2026 |
| Syeda Zahra Trust International | Professional & scientific | 2012 |
| Sygnet Health Care Services Limited | Health & social care | 2025 |
| SYL Trans Ltd | Transport & logistics | 2015 |
| Sylvia in Time Limited | Transport & logistics | 2018 |
| Symonds & Clean-A-Way Limited | Administrative & support | 2026 |
| Symphonic Gardens Limited | Professional & scientific | 2020 |
| Synapsis Talent Limited | Professional & scientific | 2026 |
| Syncom Installations Limited | Information & communication | 2005 |
| Syncom Utilities Limited | Construction | 2013 |
| Syndex UK Limited | Professional & scientific | 2014 |
| Synergin Limited | Information & communication | 2017 |
| Synergin Solutions Limited | Information & communication | 2016 |
| Synergy Notions Ltd | Professional & scientific | 2024 |
| Synergy Roofing Limited | Construction | 2013 |
| Syntax Communications Ltd | Professional & scientific | 2010 |
| Syntax Link Limited | Information & communication | 2020 |
| SYS Holding Limited | Financial services | 2012 |
| Systematic Studios Ltd | Information & communication | 2023 |
| Systemation Euro Automotive Limited | Manufacturing | 2012 |
| Systems Based Solutions Ltd | Information & communication | 2016 |
| Systemsaccountants Group Limited | Financial services | 2022 |
| Systemsaccountants Holdings Limited | Financial services | 2015 |
| Systemsaccountants Limited | Administrative & support | 1997 |
| Systorm UK Limited | Real estate | 2012 |
| Syzo Ltd | Construction | 2017 |
| Syzo Newquay Limited | Real estate | 2021 |
| SZ Delivery Ltd | Transport & logistics | 2021 |
| SZ Distribution Ltd | Wholesale & retail | 2020 |
| SZ Right Care Ltd | Health & social care | 2014 |
| Szabocomposites Ltd | Manufacturing | 2020 |
| Szar - Trans Ltd | Transport & logistics | 2019 |
| Szczepanski Trans Ltd | Transport & logistics | 2014 |
| SZV11 Ltd | Transport & logistics | 2025 |
| Szwan Ltd | Wholesale & retail | 2014 |
| Szweju&Sons Ltd | Transport & logistics | 2023 |
| Szybki Chrupek Ltd | Transport & logistics | 2024 |
| SZYMEKNO1 Transport Ltd | Transport & logistics | 2023 |
| Símona Aesthetics Ltd | Other services | 2022 |
| T & C Peterborough Ltd | Hospitality | 2026 |
| T & R Collins Properties Limited | Real estate | 2016 |
| T & T Vehicle Sales Ltd | Wholesale & retail | 2013 |
| T a Motors (Peterborough) Ltd | Wholesale & retail | 2023 |
| T Build (Cambs) Ltd | Construction | 2003 |
| T Cockburn Carpentry Limited | Construction | 2017 |
| T COX Limited | Professional & scientific | 2022 |
| T Damani Co Limited | Health & social care | 2018 |
| T Glover Transport Limited | Transport & logistics | 2025 |
| T M Parker Ltd | Manufacturing | 2021 |
| T P Snitch Brickworks Limited | Construction | 2002 |
| T S Properties and Maintenance Ltd | Construction | 2024 |
| T&I Property Services Ltd | Transport & logistics | 2019 |