| Srabl Ltd | Real estate | 2024 |
| SRG Artists Ltd | Arts & recreation | 2026 |
| Sridevi Bungalow Film UK Limited | Information & communication | 2017 |
| SRN Consultancy Limited | Professional & scientific | 2007 |
| SRN Medical Services Ltd | Health & social care | 2009 |
| Ssnb Services Limited | Professional & scientific | 2025 |
| Sswl Ltd | Wholesale & retail | 2022 |
| ST Bartholomew's School | Education | 2011 |
| ST James Flats Management Limited | Households | 1980 |
| ST John's Mews (Marlborough) Management Company Limited | Real estate | 2009 |
| ST Michaels Close (2016) Limited | Households | 2016 |
| ST Property Solutions Ltd | Real estate | 2018 |
| ST. Anne's Opportunity Centre Limited | Health & social care | 1980 |
| ST. Gabriel's Sport Centre Limited | Education | 2001 |
| ST. Lawrence's Square Management Limited | Households | 1985 |
| ST. Lukes House Limited | Real estate | 2004 |
| ST. Mary's Court Management Limited | Households | 1983 |
| ST. Mary's Place Limited | Other services | 2015 |
| St.Luke's Trustee (Berkshire) | Education | 2018 |
| Stackone Technologies Limited | Information & communication | 2023 |
| Staddle Stone Spa Limited | Other services | 2014 |
| Stag Promotions Ltd | Arts & recreation | 2025 |
| Stage UP Community Interest Company | Arts & recreation | 2023 |
| Standard Group Trading Limited | Professional & scientific | 1982 |
| Standard Tonnage Limited | Transport & logistics | 2026 |
| Standing Accordant LLP | | 2014 |
| Standing Rock Ltd | Financial services | 2023 |
| Standprof Ltd | Information & communication | 2013 |
| Stanley John Limited | Other services | 1996 |
| Stanley John Properties Limited | Real estate | 2019 |
| Stanley William Ltd | Construction | 2017 |
| Starboard Tack Property Services Ltd | Administrative & support | 2018 |
| Start 2 Finish Project Planning Ltd | Construction | 2014 |
| Starting Gates Residents Association (Newbury) Limited | Real estate | 1985 |
| Statex Limited | Wholesale & retail | 1983 |
| Stati-Cal Ltd | Extraterritorial | 2015 |
| Station Approach (Collingbourne) Management Company Limited | Households | 2020 |
| Stay Attentive Ltd | Other services | 2023 |
| Steare Medical Ltd | Professional & scientific | 2012 |
| Stearn Electric Company Limited | Wholesale & retail | 1924 |
| Steel Security Dog Leads Limited | Extraterritorial | 2021 |
| Stembridge Close Management Company Limited | Households | 2015 |
| Step Ahead Behaviour Consultancy Ltd | Education | 2024 |
| Step UP Finance Limited | Professional & scientific | 2022 |
| Stephen Brown Electrical Services Ltd | Construction | 2023 |
| Stephen Critchell Associates Limited | Construction | 1999 |
| Stephen Hanlon Limited | Arts & recreation | 2025 |
| Sterling Corporate Finance Ltd | Professional & scientific | 2026 |
| Sterling Garage Ltd | Wholesale & retail | 2015 |
| Sterling International Real Estate Ltd | Real estate | 2016 |
| Steve Crerar Water Resources Consulting Limited | Professional & scientific | 2012 |
| Steve Smith Plumbing & Heating Limited | Construction | 2010 |
| Stewart Innovation Ltd | Information & communication | 2024 |
| Stewarts Coaches Limited | Transport & logistics | 2002 |
| Still Software Solutions Limited | Information & communication | 2013 |
| Still Water Revival Ltd | Construction | 2023 |
| Stockcross Consulting Limited | Professional & scientific | 2012 |
| Stockford Circle Holdings Limited | Construction | 2019 |
| Stockford Limited | Financial services | 1981 |
| Stockham Farm Management Wantage Limited | Extraterritorial | 2013 |
| Stockham Properties Oxon 2014 Limited | Extraterritorial | 2014 |
| Stok Industries Ltd | Information & communication | 2024 |
| Stone Real Estate (Baltic) Limited | Construction | 2021 |
| Stone Real Estate Limited | Construction | 2015 |
| Stonemasons' Court Residents Management Limited | Real estate | 2005 |
| Stoneways Insurance Services Limited | Financial services | 2004 |
| Stoneways Marine Insurance Services Limited | Financial services | 2001 |
| Stonewood Solutions Ltd | Professional & scientific | 2011 |
| Stonham & Stonham Prof Services Ltd | Professional & scientific | 2018 |
| Storynate Limited | Information & communication | 2013 |
| Stowgate Limited | Extraterritorial | 2006 |
| Stowgilly Solutions Limited | Administrative & support | 2019 |
| Stprisca Ltd | Health & social care | 2023 |
| Stps Management Limited | Administrative & support | 2020 |
| Stratacast Ltd | Information & communication | 2025 |
| Strategic Staffing Solutions UK Limited | Administrative & support | 2004 |
| Strategy to Revenue Holdings Limited | Financial services | 2024 |
| Strategy to Revenue Limited | Financial services | 2008 |
| Stratfield Properties Limited | Real estate | 1965 |
| Stratopa Ltd | Information & communication | 2025 |
| Stratton Properties Limited | Real estate | 1949 |
| Stratum Finance & Business Services Limited | Professional & scientific | 2014 |
| Stratxcel Ltd | Information & communication | 2024 |
| Stream Solutions Limited | Professional & scientific | 2008 |
| Strength Coach Curriculums Ltd | Arts & recreation | 2025 |
| Strg Solutions Ltd | Professional & scientific | 2013 |
| Strike Control Ltd | Construction | 2017 |
| Strongher Ltd | Health & social care | 2025 |
| Strongtech Ltd | Information & communication | 2025 |
| Stryker UK Limited | Health & social care | 1998 |
| Stuart and Mcintosh Limited | Extraterritorial | 1993 |
| Stuart Bravery Paraplanning Limited | Other services | 2021 |
| Studio Charteris Ltd | Professional & scientific | 2023 |
| Studio Fothergill Ltd | Professional & scientific | 2024 |
| Studio Jordan Design Ltd | Professional & scientific | 2021 |
| Studio Jordan Developments Ltd | Real estate | 2021 |
| Studio Kirk Ltd | Arts & recreation | 2017 |
| Studio Wunda Ltd | Professional & scientific | 2025 |
| Stunning Kitchen & Wardrobes Ltd | Wholesale & retail | 2022 |
| Stutchbury Limited | Information & communication | 1996 |