| Spemple Limited | Health & social care | 1999 |
| Spenhead Estates Limited | Professional & scientific | 1984 |
| Spennywell Properties Ltd | Real estate | 2000 |
| Spice Centre Ltd | Hospitality | 2023 |
| Spice Ruislip Manor Limited | Hospitality | 2024 |
| Spin the Webb Ltd | Information & communication | 2017 |
| Spinview Shareholders 2 Limited | Professional & scientific | 2024 |
| Spinview Shareholders Limited | Professional & scientific | 2024 |
| Spiral Product Design Limited | Professional & scientific | 1999 |
| Splashlight Limited | Wholesale & retail | 2001 |
| Splinter Limited | Information & communication | 2004 |
| Splitz Hairdressers Limited | Other services | 2003 |
| Sportif International Limited | Administrative & support | 1992 |
| Spotlight Electrical Limited | Construction | 2005 |
| Spotoncars Limited | Administrative & support | 2007 |
| Spring Training Ltd | Education | 2022 |
| Springbank(Winchmore Hill)Property Management Co.Limited | Households | 1967 |
| Springvale Estates Limited | Real estate | 2002 |
| Springvale Imports Ltd | | 1993 |
| Spry PAY Limited | Administrative & support | 2003 |
| Square Mile Wealth Mortgages Limited | Professional & scientific | 2006 |
| SR Accounting Services Limited | Professional & scientific | 2004 |
| SR Fresh Foods Ltd | Hospitality | 2023 |
| SRC One Realty Partners Ltd | Construction | 2017 |
| SRC Realty Partners Ltd | Construction | 2016 |
| SRI Homes Limited | Real estate | 2021 |
| SRK Clucks Limited | Wholesale & retail | 2026 |
| SS Diagnostics Limited | Health & social care | 2007 |
| SSA Builders Merchants Ltd | Wholesale & retail | 2023 |
| SSB Decorating Limited | Construction | 2002 |
| ST Andrews Close Management Company Limited | Hospitality | 1986 |
| ST Brickyard Ltd | Construction | 2022 |
| ST Gabriels Social Club Limited | Other services | 2004 |
| ST. Antony's Cash & Carry Limited | Real estate | 2003 |
| St.James' Square Investment Company Limited | Construction | 1958 |
| St.Martins'(Northwood)Preparatory School Trust Limited | Education | 1961 |
| Staccatoas Ltd | Wholesale & retail | 2021 |
| Stackdrive Logistics Limited | Transport & logistics | 2018 |
| Stadium Support Services Limited | Construction | 2004 |
| Staines Printing Company Limited(The) | | 1985 |
| Stalia Services Limited | Administrative & support | 1986 |
| Stamar Properties Limited | Real estate | 2016 |
| Stampdile Limited | Wholesale & retail | 1980 |
| Stanhope Leisure Limited | | 1984 |
| Stanley Combined Am/Pm Project Ltd | Education | 2004 |
| Stanmill Brickworks Limited | Construction | 2007 |
| Stanmore Care Homes Limited | Health & social care | 2008 |
| Stansand (Brokers) Limited | Extraterritorial | 1963 |
| Stansand Limited | Extraterritorial | 1953 |
| Stantom Court Management Limited | Households | 1986 |
| Star Rides Limited | Transport & logistics | 2019 |
| Starfield Properties Limited | Other services | 2000 |
| Starlight Pictures Limited | Information & communication | 2007 |
| Startron Limited | Real estate | 2001 |
| Starworks Group Ltd | Wholesale & retail | 2015 |
| Station Court (Wembley) Management Company Limited | Households | 1983 |
| Staydan Freight Services Ltd | Transport & logistics | 2002 |
| Steadfast Heating & Plumbing Contractors Limited | | 1998 |
| Steakout Harrow Limited | Hospitality | 2013 |
| Stellar Security Ltd | Administrative & support | 2022 |
| Stephen. DOW | | 1998 |
| Sterling Professional Finance Limited | Financial services | 2002 |
| Sterling Property Finance Limited | Information & communication | 1997 |
| Steve Dridge Painters & Decorators Limited | Construction | 2002 |
| Steven Charter | | 1998 |
| Sting London Limited | Other services | 2001 |
| Stirling Civil Engineering Limited | Construction | 1963 |
| Stone Building Supplies Limited | Wholesale & retail | 2003 |
| Stone Properties Limited | Real estate | 1996 |
| Stoneage Studios Limited | Information & communication | 2014 |
| Stonethwaite Limited | Construction | 1991 |
| Straight Flush Investments Limited | Real estate | 2006 |
| Stray Twigs Ltd | Arts & recreation | 2026 |
| Streamquote Limited | Wholesale & retail | 1995 |
| Strikeglen Limited | Information & communication | 1998 |
| String NIX Ltd | Wholesale & retail | 2023 |
| Struct Solutions Ltd | Professional & scientific | 2007 |
| Structural Engineering Consultants Ltd | Professional & scientific | 1987 |
| Studio 274 Limited | Other services | 2003 |
| Studio Boult Ltd | Arts & recreation | 2009 |
| Studio JPH Ltd | Professional & scientific | 2021 |
| Studio Moren Limited | Professional & scientific | 2007 |
| Studio RM Limited | Arts & recreation | 2010 |
| STUDIO1972 Ltd | Information & communication | 2021 |
| Stuntward Limited | | 1982 |
| Success International Limited | Information & communication | 1995 |
| Sudbury Care Homes Limited | Hospitality | 2006 |
| Suggi & Suggi Retail Solutions Limited | Professional & scientific | 2006 |
| Suited Fashions Limited | Professional & scientific | 2003 |
| Sujata Banerjee Dance Company Limited | Arts & recreation | 2005 |
| Sujatha Locum Limited | Health & social care | 2024 |
| Sullivans Meats Limited | | 1979 |
| Summerfield Ground Maintenance Limited | Administrative & support | 1996 |
| Sumword Limited | Real estate | 1981 |
| Sun Mark Gulf (Holdings) Limited | Financial services | 2021 |
| Sunbury Nursing Homes Limited | Health & social care | 1996 |
| Sung WAH Taoist Association | Other services | 1985 |
| Sunlodge Properties Limited | Real estate | 1999 |
| Sunnycroft Road Limited | Real estate | 2006 |
| Sunraj Systems Ltd | Information & communication | 1998 |