| 3 Fairlawn Avenue Ltd | Real estate | 2019 |
| 3 Feet HI Live Ltd | Arts & recreation | 2022 |
| 3 Finborough Road Management Limited | Households | 1998 |
| 3 Firs Estates Limited | Real estate | 2019 |
| 3 Fitzhardinge House Ltd | Real estate | 2025 |
| 3 Flags Ltd | Professional & scientific | 2017 |
| 3 Flavours Authentic Ltd | Wholesale & retail | 2024 |
| 3 Flavours London Ltd | Hospitality | 2025 |
| 3 Flavours UK Ltd | Hospitality | 2020 |
| 3 Form Consulting Ltd | Professional & scientific | 2020 |
| 3 Friends & Company Ltd | Education | 2026 |
| 3 G Trade and Services Ltd | Wholesale & retail | 2011 |
| 3 Gales Gardens LON Limited | Administrative & support | 2018 |
| 3 Gateforth Street Freehold Limited | Households | 2024 |
| 3 Gladstone Road Management Company Limited | Real estate | 2009 |
| 3 Glenarm Road Freehold Limited | Real estate | 2026 |
| 3 Glendower Place RTM Company Ltd | Households | 2025 |
| 3 Glenloch Road Hampstead Limited | Real estate | 2001 |
| 3 Glenluce Road Management Company Limited | Households | 2009 |
| 3 GMS Freehold Company Limited | Households | 2015 |
| 3 Godwin Road RTM Limited | Households | 2009 |
| 3 Goldney Road Limited | Real estate | 2007 |
| 3 Gordon Road (Residents Association) Limited | Households | 1976 |
| 3 Gracias Limited | Professional & scientific | 2018 |
| 3 Gravity Solution Limited | Wholesale & retail | 2015 |
| 3 Greville Road Limited | Households | 1998 |
| 3 Guys Ltd | Hospitality | 2015 |
| 3 Guys Peri Peri Grill Ltd | Hospitality | 2025 |
| 3 Guys Trade Limited | Real estate | 2020 |
| 3 H & a Ltd | Construction | 2023 |
| 3 Hailsham Road Limited | Households | 2021 |
| 3 Hans Crescent Freehold Limited | Real estate | 2017 |
| 3 Harrington Gardens Limited | Real estate | 2026 |
| 3 Hart Collection Ltd | Real estate | 2015 |
| 3 Harvey Road Limited | Households | 2011 |
| 3 Hearts Canvas Ltd | Arts & recreation | 2018 |
| 3 Heathland Road Ltd | Real estate | 2020 |
| 3 Hereford Gardens (Freehold) Limited | Real estate | 2020 |
| 3 Hillfield Avenue Limited | Real estate | 2015 |
| 3 Homestead Road Limited | Real estate | 2021 |
| 3 Hubs Automation Ltd | Wholesale & retail | 2017 |
| 3 Humbolt Road Limited | Other services | 1994 |
| 3 Hurdles Ltd | Information & communication | 2023 |
| 3 Hyde Park Place Limited | Households | 1994 |
| 3 I Stack Ltd | Water & waste | 2026 |
| 3 in 1 Sofa Wall Beds Ltd | Manufacturing | 2024 |
| 3 in a Sack Limited | Manufacturing | 2014 |
| 3 in One Electronics Ltd | Wholesale & retail | 2024 |
| 3 IS the Magic Number Ltd | Arts & recreation | 2025 |
| 3 J'S International Ltd | Wholesale & retail | 2018 |
| 3 Jackson's Lane (Management Company) Limited | Households | 1998 |
| 3 Kegs Limited | Hospitality | 2018 |
| 3 Kenilworth Road Freeholders Ltd | Households | 2021 |
| 3 Kensington Square (Freehold) Limited | Real estate | 1999 |
| 3 Kinnoul Road Limited | Real estate | 2009 |
| 3 KT Limited | Real estate | 2017 |
| 3 Ladbook Limited | Real estate | 2025 |
| 3 Lambourn Road S W 4 Management Limited | Households | 1998 |
| 3 Langtry Road Freehold Limited | Households | 2019 |
| 3 Lansdowne Road Freehold Ltd | Households | 2025 |
| 3 Lansdowne Road RTM Company Limited | Households | 2016 |
| 3 Lanterns Limited | Real estate | 2024 |
| 3 Lauderdale Road Limited | Real estate | 2005 |
| 3 Leaf Capital Limited | Financial services | 2023 |
| 3 Leaf Ltd | Hospitality | 2018 |
| 3 Leamington Road Villas Ltd | Real estate | 2024 |
| 3 Lebanon Road RTM Company Limited | Households | 2025 |
| 3 Leeland Terrace Residents Management Limited | Households | 2021 |
| 3 Legged Duck Ltd | Real estate | 2025 |
| 3 Leighton Crescent Limited | Professional & scientific | 1990 |
| 3 Leinster Square Limited | Households | 2014 |
| 3 Leysfield Road Management Company Ltd. | Professional & scientific | 1998 |
| 3 Limeharbour and Roffey ST RTM Company Limited | Households | 2016 |
| 3 Lines of Defence Consulting Limited | Professional & scientific | 2014 |
| 3 Lines of Defence Group Limited | Professional & scientific | 2019 |
| 3 Lines of Defence Limited | Professional & scientific | 2019 |
| 3 Lobos LLP | | 2021 |
| 3 Locks Brewing Company Limited | Hospitality | 2022 |
| 3 Loop Music Limited | Information & communication | 2011 |
| 3 Louisville Road Ltd | Households | 2007 |
| 3 Love Hearts Handbags Collection Limited | Wholesale & retail | 2023 |
| 3 Loves Ltd | Wholesale & retail | 2021 |
| 3 Lucerne Ltd | Real estate | 2025 |
| 3 M Logistics Ltd | Wholesale & retail | 2024 |
| 3 Macfarlane Road Freehold Limited | Real estate | 2006 |
| 3 Macroom Road Management Limited | Households | 1986 |
| 3 Manor Park Management Limited | Households | 2016 |
| 3 Manstone Road London Limited | Households | 2014 |
| 3 Margravine Road (Freehold) Limited | Extraterritorial | 2009 |
| 3 Mars Consultancy Ltd | Administrative & support | 2013 |
| 3 Melon Road Limited | Real estate | 2019 |
| 3 Merchant Square (Nominee) Limited | Construction | 2006 |
| 3 Merchant Square Management Limited | Households | 2011 |
| 3 Million Words Ltd | Information & communication | 2026 |
| 3 Minute Mile Ltd | Professional & scientific | 2006 |
| 3 Missed Calls Ltd | Information & communication | 2025 |
| 3 MKA Ltd | Wholesale & retail | 2017 |
| 3 MMS Limited | Manufacturing | 2009 |
| 3 Mode Ltd | Wholesale & retail | 2024 |
| 3 Montagu Square RTM Company Limited | Households | 2009 |