| 3 Montpelier Rise Limited | Real estate | 2024 |
| 3 Montrell Road Limited | Real estate | 2015 |
| 3 More London Centre Limited | Real estate | 2010 |
| 3 Moreton Place Limited | Households | 2012 |
| 3 Mornington Crescent (Freehold) Limited | Households | 2020 |
| 3 Mount Pleasant Road Management Company Limited | Real estate | 2023 |
| 3 Musgrove Road Management Ltd | Households | 2016 |
| 3 Nascot Street Limited | Households | 2023 |
| 3 Nevern Square Limited | Extraterritorial | 2015 |
| 3 New END Ltd | Real estate | 2010 |
| 3 Norfolk Road RTM Company Limited | Households | 2006 |
| 3 North Common Road Management Limited | Households | 2001 |
| 3 Northcote Road Ltd | Real estate | 2018 |
| 3 Northlands Street Limited | Households | 1997 |
| 3 NRG Ltd | Construction | 2025 |
| 3 Nugent Terrace Management Ltd | Real estate | 2005 |
| 3 Oakley Gardens Limited | Households | 2017 |
| 3 Oakley Street Limited | Households | 2022 |
| 3 Oaks Property Group Ltd | Real estate | 2022 |
| 3 Oceans Limited | Real estate | 2000 |
| 3 OCR Limited | Construction | 2018 |
| 3 of 1 Ltd | Wholesale & retail | 2025 |
| 3 of Three Ltd | Wholesale & retail | 2025 |
| 3 Oglander Road Limited | Households | 2023 |
| 3 on the Road Estates Limited | Real estate | 2024 |
| 3 Ovington Square Management Limited | Real estate | 2009 |
| 3 Owls Consulting Ltd | Information & communication | 2025 |
| 3 Paradise Gardens Limited | Real estate | 2016 |
| 3 Park Road (Freehold) Limited | Households | 2022 |
| 3 Peaks Health Limited | Health & social care | 2023 |
| 3 Pembridge Crescent Limited | Households | 1991 |
| 3 Penn Road RTM Company Limited | Households | 2026 |
| 3 Penrith Invest Ltd | Real estate | 2025 |
| 3 Penywern Road Limited | Real estate | 2004 |
| 3 Perrymead Freehold Limited | Real estate | 2011 |
| 3 Perwell Avenue Limited | Real estate | 2025 |
| 3 Peterborough Villas (Fulham) Management Company Limited | Households | 2017 |
| 3 Phase Electrical Solutions Ltd | Construction | 2022 |
| 3 Phase Holdings Ltd | Manufacturing | 2025 |
| 3 Picton Place Limited | Financial services | 2015 |
| 3 Pillar Holdings Limited | Financial services | 2025 |
| 3 Pillar Land Limited | Construction | 2026 |
| 3 Pillar Port Limited | Transport & logistics | 2026 |
| 3 Pillar Property Ltd | Households | 2018 |
| 3 Pillar Seaways Limited | Transport & logistics | 2026 |
| 3 Pillars Civils Ltd | Construction | 2026 |
| 3 Point Retail and Commercial Ltd | Wholesale & retail | 2026 |
| 3 Pont Street Limited | Real estate | 2009 |
| 3 Power Limited | Wholesale & retail | 2020 |
| 3 Preston Ltd | Real estate | 2022 |
| 3 Primrose Gardens Management Company Limited | Households | 2006 |
| 3 Probyn Road RTM Company Limited | Households | 2007 |
| 3 Properties Holdings Ltd | Real estate | 2021 |
| 3 Prospero Road Freehold Limited | Households | 2025 |
| 3 Prospero Road RTM Company Limited | Households | 2010 |
| 3 Queen's Gate RTM Company Limited | Households | 2005 |
| 3 Radford Road (Freehold) Limited | Households | 2007 |
| 3 Radipole Road (Management) Limited | Households | 1984 |
| 3 Reasons Limited | Professional & scientific | 2014 |
| 3 Red Groups Limited | Financial services | 2025 |
| 3 Redcliffe Square Limited | Households | 1997 |
| 3 Rgfh Company Limited | Households | 1995 |
| 3 Richford Street Limited | Households | 2012 |
| 3 River Terrace (Henley) Limited | Households | 2005 |
| 3 Rivers Clinic Limited | Administrative & support | 2009 |
| 3 Rivers Property Holdings Limited | Real estate | 2021 |
| 3 Rock Productions Limited | Administrative & support | 2018 |
| 3 Roland Gardens (Management Company) Limited | Households | 2021 |
| 3 Rosecroft Avenue Limited | Households | 2001 |
| 3 Royal Crescent Limited | Hospitality | 1993 |
| 3 Rutland Gate Limited | Households | 1983 |
| 3 Sandwell Crescent Limited | Households | 1995 |
| 3 Savile ROW Limited | Real estate | 2006 |
| 3 Seafield Road Limited | Real estate | 2012 |
| 3 Sevington Street Limited | Households | 2000 |
| 3 Seymer Place Limited | Real estate | 2016 |
| 3 Sheep Limited | Information & communication | 2008 |
| 3 Shields Risk Solutions Ltd | Administrative & support | 2026 |
| 3 Sigma Capital Ltd | Professional & scientific | 2021 |
| 3 Sinclair Gardens Limited | Households | 2003 |
| 3 Sisters Ventures Collective Ltd | Financial services | 2023 |
| 3 Sixteen Properties Ltd | Real estate | 2025 |
| 3 Sixti Ltd | Financial services | 2003 |
| 3 Sixty Plant Hire Limited | Construction | 2017 |
| 3 Sixty Studios Limited | Information & communication | 2004 |
| 3 Slices Ltd | Wholesale & retail | 2013 |
| 3 Smart Fellas Ltd | Arts & recreation | 2023 |
| 3 South Villas (Camden NW1) Management Company Limited | Real estate | 2001 |
| 3 Spirits Productions Limited | Information & communication | 2025 |
| 3 Squared Management Ltd | Real estate | 2021 |
| 3 Squeeze Holdings Limited | Real estate | 2019 |
| 3 ST Charles Square RTM Company Limited | Households | 2004 |
| 3 ST Georges Road Ltd | Real estate | 2019 |
| 3 ST Mary Road (Freehold) Limited | Households | 2023 |
| 3 ST Mary's Terrace Limited | Households | 1995 |
| 3 ST. Ann's Crescent Limited | Households | 1995 |
| 3 ST. Johns Road Limited | Administrative & support | 2009 |
| 3 Star Kebabish Ltd | Hospitality | 2019 |
| 3 Star Motors Ltd | Wholesale & retail | 2024 |
| 3 Star Organic Ltd | Hospitality | 2025 |