| 3 Birkbeck Road Management Limited | Real estate | 1997 |
| 3 Bloomsbury SQ Ltd | Real estate | 2025 |
| 3 Blue - Kempshott Ltd | Real estate | 2007 |
| 3 Blue - Wellfield Ltd | Real estate | 2007 |
| 3 Blue-Becmead Ltd | Real estate | 2007 |
| 3 Blue-Greyhound Ltd | Real estate | 2007 |
| 3 Blue-Monson Ltd | Real estate | 2007 |
| 3 Bohemia Road Ltd | Construction | 2026 |
| 3 Bothers Food and Drinks Ltd | Wholesale & retail | 2026 |
| 3 Boys Creations Ltd | Wholesale & retail | 2024 |
| 3 Bradiston Road Limited | Households | 2020 |
| 3 Brewster Road Management Company Limited | Households | 2021 |
| 3 Briars Close Limited | Real estate | 2024 |
| 3 Bridges (London) Freehold Limited | Households | 2005 |
| 3 Brix Ltd | Construction | 2023 |
| 3 Brondespark Limited | Households | 2024 |
| 3 Brothers Consulting Ltd | Extraterritorial | 2016 |
| 3 Bruces Limited | Real estate | 2015 |
| 3 Brussels Road (Freehold) Limited | Households | 2019 |
| 3 Build Construction Ltd | Construction | 2021 |
| 3 Burnley Road Management Company Limited | Real estate | 2007 |
| 3 Butchers Ltd | Wholesale & retail | 2019 |
| 3 C'S Construction Services Ltd | Construction | 2004 |
| 3 Calonne Road Management Limited | Households | 2015 |
| 3 Campsbourne Road Limited | Households | 2003 |
| 3 Cargreen Road RTM Company Ltd | Real estate | 2017 |
| 3 Carlingford Road Limited | Real estate | 2023 |
| 3 Castellain Road Limited | Real estate | 2006 |
| 3 Cats Group Limited | Information & communication | 2019 |
| 3 Cavendish Road Management Limited | Households | 2012 |
| 3 Cawnpore Street Ltd | Real estate | 2025 |
| 3 Cecile Park Management Limited | Households | 2000 |
| 3 Charleston Street Limited | Extraterritorial | 2013 |
| 3 Charlwood Place Limited | Real estate | 2019 |
| 3 Cheyne Terrace Limited | Households | 2015 |
| 3 Chillies Studio Limited | Professional & scientific | 2025 |
| 3 Chord Pro Ltd. | Administrative & support | 2022 |
| 3 Church Crescent Limited | Extraterritorial | 2004 |
| 3 Claverton Street Residents Limited | Real estate | 1999 |
| 3 Clifford Road (Bexhill) Limited | Households | 2004 |
| 3 Cliffs Bay Productions Limited | Information & communication | 2025 |
| 3 Clifton Road Management Limited | Households | 2018 |
| 3 Clitheroe Road Freehold Property Limited | Households | 2017 |
| 3 Colinette Road Limited | Households | 2012 |
| 3 Collingham Place Limited | Households | 2011 |
| 3 Colours Rule Limited | Other services | 2015 |
| 3 Comeragh Road RTM Company Ltd | Households | 2014 |
| 3 Compton Terrace RTM Company Limited | Real estate | 2006 |
| 3 Conduit Street Limited | Real estate | 2026 |
| 3 Coolhurst Road Limited | Households | 1984 |
| 3 Copse Hill Management Company Limited | Real estate | 1996 |
| 3 Cord Limited | Professional & scientific | 1996 |
| 3 Cords Communications Ltd | Professional & scientific | 2026 |
| 3 Countess Road Limited | Households | 2017 |
| 3 Counties Grounds Maintenance Ltd | Administrative & support | 2022 |
| 3 Counties Roofing and Building Limited | Construction | 2022 |
| 3 Courtfield Gardens Management Limited | Households | 2017 |
| 3 Creffield Road Ltd | Households | 2006 |
| 3 Cribs Ltd | Real estate | 2021 |
| 3 Cromwell Crescent Management Company Limited | Households | 1988 |
| 3 CS Services Ltd | Wholesale & retail | 2020 |
| 3 Dagnan Road Freehold Limited | Households | 2013 |
| 3 Dancer Road Limited | Households | 2022 |
| 3 Dartmouth Road Residents Association Limited | Households | 1983 |
| 3 Dartmouth Terrace Limited | Households | 2013 |
| 3 Days Agency Limited | Arts & recreation | 2022 |
| 3 Days Holding Limited | Financial services | 2024 |
| 3 Degrees World Ltd | Households | 2022 |
| 3 Delis Limited | Hospitality | 2021 |
| 3 Diamonds International Limited | Extraterritorial | 2007 |
| 3 Dimension Design Technologies Ltd | Wholesale & retail | 2005 |
| 3 Dimensional Projects Ltd | Professional & scientific | 2010 |
| 3 Dimensions Southern LLP | | 2020 |
| 3 Dish Digital Solutions Ltd | Information & communication | 2026 |
| 3 Dodd Enterprises Ltd | Financial services | 2023 |
| 3 Doors Limited | Information & communication | 2021 |
| 3 Dots Capital Advisory Ltd | Professional & scientific | 2023 |
| 3 Dots ENG Ltd | Construction | 2021 |
| 3 Dots Invest Ltd | Real estate | 2022 |
| 3 Durham Terrace Limited | Professional & scientific | 2001 |
| 3 Eardley Crescent Limited | Households | 2025 |
| 3 Eaton Place Freehold Limited | Households | 2018 |
| 3 Eatonville Road Limited | Households | 2016 |
| 3 Edge Hill RTM Company Limited | Households | 2021 |
| 3 Egerton Place Limited | Households | 2004 |
| 3 Eggs Management Ltd | Real estate | 2020 |
| 3 Eglantine Road Limited | Households | 2010 |
| 3 Eleven Investments Limited | Real estate | 2025 |
| 3 Eliot Hill Management Company Limited | Households | 1996 |
| 3 Elmbourne Freehold Limited | Households | 2017 |
| 3 Elmbourne Road RTM Company Limited | Real estate | 2012 |
| 3 Elsenham Street Residents Association Ltd | Households | 2015 |
| 3 Elsworthy Rise Limited | Real estate | 2023 |
| 3 Emperors Gate Management Company Limited | Real estate | 2011 |
| 3 Ennismore Gardens Freehold Limited | Real estate | 2025 |
| 3 EPR Ltd | Households | 2023 |
| 3 Essendine Road Limited | Households | 2006 |
| 3 Exeter Road Management Company Ltd | Real estate | 2003 |
| 3 Eyes Global Limited | Information & communication | 2022 |
| 3 Eyot Gardens Limited | Households | 2022 |