| 3QD Sadlers House Ltd | Ashford | 2023 |
| 3R (AB) Ltd | Cuminestown | 2015 |
| 3R Build Solutions Limited | Wolverhampton | 2024 |
| 3R Construction Ltd | Congleton | 2026 |
| 3R Electrical Ltd | London | 2024 |
| 3R Glass and Glazing Limited | Glasgow | 2022 |
| 3R Services Group Ltd | Sandhurst | 2025 |
| 3R Tech Limited | Loughborough | 2012 |
| 3RD Generation Roofing Limited | Bedford | 2022 |
| 3RD Group Limited | Lincoln | 2009 |
| 3RD Rail Resource Ltd | London | 2021 |
| 3RD Venture Limited | Manchester | 2025 |
| 3RE Capital Ventures UK Limited | London | 2018 |
| 3RONI Limited | Folkestone | 2022 |
| 3RS Engineering Limited | Rotherham | 2020 |
| 3RS Property Development Ltd | Halesowen | 2023 |
| 3S and D Limited | Southsea | 2003 |
| 3S Bridge Limited | London | 2018 |
| 3S Building Ltd | Worcester | 2025 |
| 3S Construction Ltd | London | 2022 |
| 3S Electrical (UK) Ltd | Southampton | 2016 |
| 3S Homes Ltd | Bristol | 2022 |
| 3S Northampton Limited | Northampton | 2015 |
| 3SB Conversions Ltd | Chatham | 2021 |
| 3SB Group Ltd. | Lisburn | 2017 |
| 3SC Group Scaffolding Limited | Weymouth | 2025 |
| 3SC Scaffolding Ltd | Weymouth | 2019 |
| 3SGUK Limited | Harrow | 2015 |
| 3SHIRES ATM Solutions Ltd | Rotherham | 2019 |
| 3SHIRES Building Limited | Rotherham | 2010 |
| 3SIXTY Building Ltd | High Wycombe | 2018 |
| 3SIXTY Construction Limited | Downpatrick | 2016 |
| 3SIXTY Facilities Solutions Ltd | Manchester | 2025 |
| 3SIXTY Fitout Solutions Limited | Plymouth | 2019 |
| 3SIXTY Flooring Limited | Wallingford | 2009 |
| 3SIXTY Interiors Ltd | London | 2023 |
| 3SIXTY Projects Design & Build Ltd | Henley-On-Thames | 2020 |
| 3SIXTY Projects Limited | Henley-On-Thames | 2020 |
| 3SIXTY Property Development Ltd | Southport | 2026 |
| 3SIXTY Rigging & Lifting Ltd | London | 2022 |
| 3SJ Ltd | Sevenoaks | 2007 |
| 3SN Developers Limited | Ilford | 2019 |
| 3SPACE Nottingham Limited | Nottingham | 2013 |
| 3SPN 1.0 Ltd | Manchester | 2021 |
| 3SQR Limited | London | 2015 |
| 3STEPLIFTS Limited | Bradford | 2013 |
| 3SW Land Investments Limited | Tadworth | 2025 |
| 3T Building Solutions Ltd | London | 2026 |
| 3T GAS Maintenance Limited | Burntwood | 2015 |
| 3T Holdings Limited | Wigan | 2020 |
| 3T Insulations Ltd | Nottingham | 2018 |
| 3T Projects Limited | Rochdale | 2019 |
| 3T Properties Limited | Reading | 2000 |
| 3T Restoration Ltd | Yeovil | 2021 |
| 3T Safety and Training Limited | Cardiff | 2023 |
| 3TI Energy Hubs Ltd | Northampton | 2019 |
| 3TP Developments Ltd | Stamford | 2025 |
| 3UK Ltd | Chigwell | 2024 |
| 3UNIQUE Ltd | Norwich | 2018 |
| 3VI Coote Lane Land Ltd | London | 2018 |
| 3VIEWDEVELOPMENTS Ltd | London | 2024 |
| 3W Construction Ltd | Feltham | 2021 |
| 3W Developments Ltd | Salisbury | 2025 |
| 3WAY Civil Solutions Limited | Rochdale | 2021 |
| 3WEST (Bramley) Ltd | Exeter | 2025 |
| 3WEST (Exton) Ltd | Exeter | 2025 |
| 3WEST (Ipplepen) Ltd | Exeter | 2025 |
| 3WEST (Ivybridge) Ltd | Exeter | 2025 |
| 3WEST (Riseley) Ltd | Exeter | 2026 |
| 3WEST (Woodbury) Ltd | Exeter | 2024 |
| 3WILLOWS Limited | Birmingham | 2014 |
| 3WM Developments Limited | London | 2022 |
| 3XC Fibre Ltd | Aberdeen | 2025 |
| 3XC Group Ltd | Fareham | 2025 |
| 3XS Ltd | Kingston Upon Thames | 2010 |
| 3Z Construction Ltd | Woodford Green | 2017 |
| 3ZERO2 Projects Ltd | Sheffield | 2023 |
| 4 Absolute Eco Construction Limited | Milton Keynes | 2016 |
| 4 Aces Brickwork Ltd | Epsom | 2019 |
| 4 Aces Builders Ltd | Wolverhampton | 2025 |
| 4 Albion Place Limited | London | 2026 |
| 4 ALL Construction Ltd | London | 2018 |
| 4 ALL Electrical Ltd | Leeds | 2025 |
| 4 ATL 404 Ltd | London | 2019 |
| 4 Beaver Ltd | Northolt | 2018 |
| 4 Brothers Brickwork Limited | London | 2023 |
| 4 Brothers Cela Ltd | London | 2020 |
| 4 Brothers Constructions Ltd | Chatham | 2020 |
| 4 Browns Close Ltd | Haywards Heath | 2022 |
| 4 BS Concrete & Screed Ltd | Birmingham | 2024 |
| 4 Chester Road Management Limited | Borehamwood | 2003 |
| 4 Cogs Development Management Limited | Northampton | 2022 |
| 4 Construction Management Ltd | Liverpool | 2022 |
| 4 Core Electrical Contractors Ltd | Leicester | 2018 |
| 4 Corner Construction Ltd | Halifax | 2026 |
| 4 Corners Projects Ltd | Hull | 2018 |
| 4 Counties OIL Heating Specialists Ltd | Haverhill | 2025 |
| 4 Counties Plumbing & Heating Services Limited | Hitchin | 2012 |
| 4 Counties Services Limited | Bedford | 2004 |
| 4 County Commercial Interiors Limited | March | 2025 |