| 3E'S Supporting Business and People Ltd | Pontypridd | 2024 |
| 3EEE Ltd | Dagenham | 2022 |
| 3EEE- Construction Limited | London | 2022 |
| 3ELEMENTS Construction Limited | Doncaster | 2018 |
| 3ES Electrical Ltd | Dagenham | 2018 |
| 3F Construction Ltd | Slough | 2025 |
| 3F Developments Ltd | Poole | 2023 |
| 3F Flooring Ltd | Romford | 2020 |
| 3F Scaffolding Ltd | Salford | 2022 |
| 3F2 Carpentry and Building Limited | Bruton | 2011 |
| 3FD Construction Ltd | Waterlooville | 2026 |
| 3FLOW Flue Installation Ltd | Redditch | 2020 |
| 3FOLD Carpentry Ltd | Rickinghall, Diss | 2023 |
| 3FOUR5 Joinery Limited | Accrington | 2010 |
| 3G Carpentry Limited | Cheltenham | 2018 |
| 3G Construction (MID Wales) Ltd | Newtown | 2016 |
| 3G Construction Ltd | Bideford | 2026 |
| 3G Controls Limited | Worksop | 2005 |
| 3G Electrical Services Limited | Chester | 2017 |
| 3G Glazing Ltd | Leicester | 2018 |
| 3G Glazing System Ltd | Leicester | 2018 |
| 3G Plant and Construction Limited | Bedford | 2023 |
| 3G Strategy Ltd | Dalkeith | 2006 |
| 3G Woodworking Limited | Leeds | 2017 |
| 3G'S Civils Ltd | Coventry | 2023 |
| 3GB Limited | Bucks | 2003 |
| 3GEN Construction Limited | Wimborne | 2012 |
| 3GEN Electrical Ltd | Oldham | 2022 |
| 3GL Build Solutions Group Ltd | Basildon | 2026 |
| 3GP Limited | Nottingham | 2018 |
| 3H Builders Ltd | Hayes | 2018 |
| 3H Construction Ltd | Hove | 2023 |
| 3H Electrics Limited | Stockton-On-Tees | 2017 |
| 3H GAS Solutions Ltd | Leicester | 2025 |
| 3H Properties Ltd | Manchester | 2011 |
| 3HEAT Electrical Ltd | Bristol | 2025 |
| 3HEAT Limited | Princes Risborough | 2020 |
| 3HEAT Plumbing & Heating Ltd | Bristol | 2022 |
| 3HEG Limited | Wirral | 2021 |
| 3HFO Ltd | Chester | 2026 |
| 3HREE 65 Services Ltd | Swansea | 2017 |
| 3IGF Ltd | Romford | 2015 |
| 3ITEK Ltd | Langdon Hill | 2005 |
| 3J Electrical Ltd | Worcester | 2022 |
| 3J Glazing Limited | West Bromwich | 2015 |
| 3J Systems & Services Limited | Worcester | 2021 |
| 3JAIS Ltd | Orpington | 2019 |
| 3JDF Services Limited | East Sussex | 2023 |
| 3JM Ltd | Yateley | 2010 |
| 3JR Properties Ltd | Belfast | 2026 |
| 3K Casa Ltd | London | 2020 |
| 3K Construction Ltd | Leicester | 2020 |
| 3K Electrical Services Ltd | Gillingham | 2014 |
| 3K Industrial Blasting and Coating Services Ltd | Darlington | 2023 |
| 3KPM Limited | Leighton Buzzard | 2021 |
| 3KR Property Ltd | London | 2026 |
| 3KY Mayfair Limited | Bexley | 2022 |
| 3L Construction Ltd | Surbiton | 2023 |
| 3L Electrical Limited | Potters Bar | 2006 |
| 3LANCE Developments Limited | Bournemouth | 2017 |
| 3LEVATE Developments Ltd | Leeds | 2025 |
| 3LR Resin Systems Ltd | Ashton-Under-Lyne | 2026 |
| 3M Building Services Ltd | London | 2024 |
| 3M Construction Ltd | Hornchurch | 2026 |
| 3M Construction Services Ltd | Luton | 2016 |
| 3M Contracts Ltd | Motherwell | 2020 |
| 3M Driveways and Groundworks Ltd | Bristol | 2017 |
| 3M Multi-Task Ltd | Thetford | 2018 |
| 3M Projects Ltd | Rochdale | 2024 |
| 3M Property Ltd | Stamford | 2013 |
| 3M RES Technology Ltd | London | 2018 |
| 3M'S Roofing Ltd | High Wycombe | 2025 |
| 3MAC Ltd | Stonehaven | 2026 |
| 3MACPROPERTIES Ltd | Inverness | 2024 |
| 3MF Construction and Electrical Company Ltd | London | 2013 |
| 3MFS Ltd | Weybridge | 2022 |
| 3MS Construction Limited | Cardiff | 2010 |
| 3MS Gold Services Limited | Birmingham | 2007 |
| 3MT Skyline Construction Ltd | Barking | 2026 |
| 3MUSKATIERS Ltd | Portsmouth | 2022 |
| 3N3R6Y Limited | Chertsey | 2024 |
| 3NAS Ltd | Birmingham | 2026 |
| 3NC Construction Ltd | Ayr | 2025 |
| 3ND Project Limited | Glasgow | 2023 |
| 3NEA Construction Ltd | Bracknell | 2021 |
| 3NERGY Limited | Loanhead | 2012 |
| 3NJ Ltd | Borehamwood | 2016 |
| 3P Construct Limited | Mexborough | 2024 |
| 3P Contract Services Ltd | Scarborough | 2018 |
| 3P Effects Decorating Ltd | Norwich | 2022 |
| 3P Renovations Ltd | Lee-On-The-Solent | 2025 |
| 3P'S Plumbing & Heating Ltd | Southall | 2016 |
| 3PHILS Construction Ltd | Salford | 2026 |
| 3PM Construction Ltd | Huntingdon | 2020 |
| 3PM Consulting Limited | London | 2015 |
| 3PREREFURBISHMENT Limited | Luton | 2023 |
| 3PS Development Ltd | Telford | 2025 |
| 3PS Lift Ltd | South Croydon | 2025 |
| 3PT Painter and Decorator Ltd | Thirsk | 2026 |
| 3Q Properties Ltd | Newry | 2024 |