| 3 Star Property Comfort Limited | Real estate | 2021 |
| 3 Stars Above Limited | Manufacturing | 2013 |
| 3 Stars Investment Ltd | Real estate | 2017 |
| 3 Station Road Twickenham Limited | Households | 2025 |
| 3 Step Innovation Limited | Transport & logistics | 2025 |
| 3 Step IT Services Limited | Administrative & support | 2021 |
| 3 Sticks Housing Ltd | Households | 2026 |
| 3 Stonor Road Management Company Limited | Households | 2008 |
| 3 Storeys Residential Ltd | Real estate | 2023 |
| 3 Stories High Limited | Professional & scientific | 2009 |
| 3 Stormont Road Holdings Limited | Households | 2017 |
| 3 Strides Cloud Consulting Limited | Administrative & support | 2023 |
| 3 Style Plus Limited | Administrative & support | 2006 |
| 3 Sugar House Lane Limited | Construction | 2019 |
| 3 Sulgrave Road Limited | Households | 2023 |
| 3 Sunderland Terrace Limited | Real estate | 2005 |
| 3 Sunningfields Crescent RTM Company Ltd | Households | 2017 |
| 3 Thames Road Limited | Administrative & support | 2018 |
| 3 the Close Freehold Limited | Households | 2023 |
| 3 the Green Ltd | Real estate | 2019 |
| 3 the Vale Ltd | Extraterritorial | 2009 |
| 3 Thornton Hill Management Limited | Households | 2022 |
| 3 Tivoli Place Limited | Real estate | 2026 |
| 3 to 1 Films Club Ltd | Arts & recreation | 2025 |
| 3 Tudor Road RTM Company Ltd | Real estate | 2009 |
| 3 Upper Brook Street Freehold Company Limited | Real estate | 2025 |
| 3 Upper Brook Street Management Company Limited | Construction | 1991 |
| 3 Valmar Road Freehold Company Limited | Households | 2015 |
| 3 Valued Things Ltd | Professional & scientific | 2021 |
| 3 Vardens Road Limited | Real estate | 1996 |
| 3 Veronica RD RTM Co Ltd | Households | 2018 |
| 3 Vicarage Ltd | Real estate | 2026 |
| 3 Victoria Road Management Company Limited | Households | 2024 |
| 3 Villiers Road Limited | Financial services | 2005 |
| 3 Waldegrave Road Freehold Limited | Households | 2021 |
| 3 Warwick Road Limited | Households | 1998 |
| 3 Warwick Road, (Redland) Management Co. Limited | Households | 1986 |
| 3 Waterhouse Square Tenant Limited | Real estate | 2015 |
| 3 Web Digital Ltd | Professional & scientific | 2023 |
| 3 Welbeck Street Limited | Households | 1986 |
| 3 Westbourne Crescent Freehold Limited | Households | 2013 |
| 3 Westgate Terrace Management Limited | Households | 1990 |
| 3 Wetherby Gardens Limited | Households | 1983 |
| 3 Wheelers Limited | Information & communication | 2005 |
| 3 White Hart Lane N22 Ltd | Households | 2018 |
| 3 Whitworth Road Freehold Limited | Households | 2021 |
| 3 Widows Limited | Information & communication | 2022 |
| 3 Wimpole Street Limited | Administrative & support | 2025 |
| 3 Windmill Drive (Freehold) Ltd | Households | 2014 |
| 3 Wix's Lane Freehold Limited | Real estate | 2001 |
| 3 Woolstone Road Management Services Limited | Households | 2013 |
| 3 Worlingham Road Freehold Limited | Households | 2009 |
| 3 WTR Freehold Limited | Households | 2017 |
| 3 X League Ltd | Information & communication | 2020 |
| 3 Years Ahead Ltd | Real estate | 2022 |
| 3 York Road RTM Company Ltd | Households | 2015 |
| 3&5 ST Georges Square Freehold Limited | Households | 2013 |
| 3&T Limited | Wholesale & retail | 2026 |
| 3, 4 & 5 Blomfield Road Limited | Households | 1989 |
| 3, 5 & 7 Ainger Road Management Limited | Extraterritorial | 1974 |
| 3, 5 and 7 Ainger Road Limited | Households | 2000 |
| 3, South Hill Park Gardens Limited | Professional & scientific | 1979 |
| 3-10 Grosvenor Crescent Management Limited | Professional & scientific | 2010 |
| 3-16HOLDINGS Limited | Professional & scientific | 2016 |
| 3-17 the Mall Ealing Limited | Real estate | 2000 |
| 3-2-1 Launch Ltd | Information & communication | 2023 |
| 3-27 Wilcox Road Holding Limited | Financial services | 2023 |
| 3-27 Wilcox Road Limited | Real estate | 2023 |
| 3-27 Wilcox Road Management Ltd | Real estate | 2025 |
| 3-4 Hardwick Limited | Real estate | 2022 |
| 3-5 Cheyne Place Ltd | Households | 2026 |
| 3-5 Queen Square Management Limited | Real estate | 2010 |
| 3-5 Randolph Crescent Limited | Households | 1982 |
| 3-6 Grafton Crescent Limited | Households | 2000 |
| 3-6-9-13 Dragons Ltd | Financial services | 2021 |
| 3-61 Ravensdale Ltd | Households | 2018 |
| 3-7 Cannon Street Management Company Limited | Households | 2014 |
| 3-7 the Avenue Brondesbury Park LP | | 2016 |
| 3-7 Walpole Street London Limited | Households | 2014 |
| 3-9 East Hill Management Co Limited | Households | 2015 |
| 3-D Matrix UK Limited | Other services | 2015 |
| 3-FOLD Games Ltd | Information & communication | 2019 |
| 3-FROM Ltd | Wholesale & retail | 2025 |
| 3-M Main Manufacturing and Maintenance Ltd | Wholesale & retail | 2022 |
| 3-SPHERE London Ltd | Professional & scientific | 2014 |
| 3-WAVES Media Project CIC | Information & communication | 2025 |
| 3.14 Pictures Ltd | Information & communication | 2024 |
| 3.1415 Limited | Professional & scientific | 2023 |
| 3.14PER Ltd | Hospitality | 2022 |
| 3.14ZDEC Ltd | Information & communication | 2024 |
| 3.16 Productions Ltd | Arts & recreation | 2020 |
| 3.NG Limited | Professional & scientific | 2025 |
| 3/4 Balfour Place Limited | Households | 1996 |
| 3/4 Mallow Street Management Limited | Households | 1998 |
| 3/4/5 Onslow Gardens Limited | Households | 2004 |
| 30 & 30A Collingbourne Road Freehold Company Limited | Households | 2020 |
| 30 & 32 Weir Road Management Company Limited | Households | 2008 |
| 30 Aberdeen Place Limited | Households | 2012 |
| 30 Ainger Road NW3 Limited | Households | 1998 |
| 30 Altenburg Gardens Limited | Real estate | 2018 |