| 38 QR Ltd. | Edgware | 2019 |
| 38 Tetherdown Limited | Potters Bar | 2006 |
| 38-41 ST. Clements Mansions Limited | London | 2018 |
| 38-43 Strand-On-The-Green Residents Association Limited | London | 1974 |
| 38.6 Solutions Ltd | St. Asaph | 2016 |
| 38.6 Support Service Ltd | Rhyl | 2026 |
| 3812 Gallery (UK) Limited | London | 2018 |
| 386EVENTS Ltd | Surbiton | 2014 |
| 38SERVICES Management Ltd | London | 2025 |
| 39 & 41 South Street Management Limited | London | 2013 |
| 39 Ardbeg Road Management Limited | London | 2014 |
| 39 Fire and Security Limited | Dartford | 2025 |
| 39 Floors Limited | London | 2020 |
| 39 Hoyle RD Ltd | London | 2020 |
| 39 Mildmay Park (Management) Limited | | 2005 |
| 39 Riggindale Road Ltd | London | 2025 |
| 39 Southampton Way Limited | London | 1996 |
| 39 SVP Flexible Working Ltd | Glasgow | 2017 |
| 3939 Management Limited | 3 Dorset Rise | 2015 |
| 3975 Limited | Cradley Heath | 2011 |
| 397CONSULTANCY Limited | Warrington | 2026 |
| 39VIS Ltd | Sawbridgeworth | 2019 |
| 3:15 Limited | High Wycombe | 2005 |
| 3A Business Solutions Ltd | Barrow In Furness | 2018 |
| 3A Consult UK Ltd | Cardiff | 2016 |
| 3A Experts UK Limited | Bury | 2024 |
| 3A Investment (International) Ltd | London | 2021 |
| 3A Saturn Ltd | London | 2025 |
| 3A Strategies Limited | Mexborough | 2016 |
| 3A Wonderland Ltd | Bedford | 2025 |
| 3ALPHA Consulting Ltd | Watford | 2017 |
| 3ANDBAG Ltd | London | 2025 |
| 3ANGELS Healthcare Professional Ltd | Doncaster | 2012 |
| 3AT1 Franchising International Limited | London | 2017 |
| 3B Brothers Ltd | Hounslow | 2024 |
| 3B Electronics Ltd | Darlaston | 2020 |
| 3B Hire and Servicing Limited | Buckinghamshire | 2006 |
| 3B Plant Hire Ltd | Cambridge | 2024 |
| 3B Projects Ltd | Alcester | 2020 |
| 3B Rail Limited | Wolverhampton | 2024 |
| 3B Recruitment Ltd | Heskin | 2013 |
| 3B Vehicle Hire Limited | Long Crendon | 1996 |
| 3B'S Group Ltd | London | 2025 |
| 3BB-BRIGHTON Ltd | Brighton | 2023 |
| 3BCARE Ltd | Basildon | 2016 |
| 3BH Limited | London | 2024 |
| 3BS Associates Ltd | Telford | 2021 |
| 3BS Limited Company Ltd | Bordon | 2019 |
| 3C 273 Limited | London | 2022 |
| 3C Building Consultancy Limited | Gateshead | 2022 |
| 3C Environmental Technology Ltd | Alcester | 1980 |
| 3C Group (UK) Ltd | Neston | 2007 |
| 3C Holdings Limited | Doncaster | 1998 |
| 3C Online Limited | London | 2014 |
| 3C Resourcing Limited | Berkeley | 2023 |
| 3C'S83 Ltd | London | 2019 |
| 3CAT Independent Mind Ltd | Stevenage | 2015 |
| 3CATS Limited | Manchester | 2018 |
| 3CCP Limited | Nantwich | 2025 |
| 3CLS Investments Limited | Edinburgh | 2021 |
| 3CORE Ltd | Wishaw | 2025 |
| 3CS Cleaning & Installation Services Ltd | Craigavon | 2020 |
| 3CUBED Search Ltd | Cardiff | 2016 |
| 3D Acad Ltd | Maldon | 2009 |
| 3D Aesthetics Ltd | Preston | 2017 |
| 3D and 3RS Ltd | Cambridge | 2023 |
| 3D Avenue Ltd | Northfleet - Gravesend | 2016 |
| 3D BPM Solutions Ltd | Sutton | 2011 |
| 3D Carpet Maintenance Ltd | Feltham | 2019 |
| 3D Cleaning Services UK Ltd | Leicester | 2016 |
| 3D Composite Manufacturing Ltd | Chichester | 2017 |
| 3D Creations Limited | Great Yarmouth | 2010 |
| 3D Creative Packaging Limited | Stoke On Trent | 2010 |
| 3D Cutting Edge Limited | Altrincham | 2009 |
| 3D Design Solutions Ltd | Surrey | 2006 |
| 3D Detailing Ltd | Chorley | 2024 |
| 3D Digital Dynamix Limited | London | 2023 |
| 3D EDS Limited | Warrington | 2012 |
| 3D Exhibitions Limited | Greenock | 2010 |
| 3D Fabrications Limited | Bromsgrove | 1998 |
| 3D Facilities Limited | Sutton Coldfield | 2015 |
| 3D Facilities Support Limited | Sutton Coldfield | 2011 |
| 3D FM Ltd | Sutton Coldfield | 2012 |
| 3D Garden Design Limited | Beith | 2005 |
| 3D Garden Designers Ltd | Waltham Cross | 2018 |
| 3D Home Automation Limited | Southampton | 2008 |
| 3D House Ltd | Beckenham | 2022 |
| 3D INK Limited | Northampton | 2002 |
| 3D Janitorial Services Ltd | London | 2025 |
| 3D Lasertec Limited | Nottingham | 1998 |
| 3D Leisure (Hotels) Ltd | Farnham | 2020 |
| 3D Leisure (Jurys) Limited | Farnham | 2020 |
| 3D Leisure Limited | Farnham | 1990 |
| 3D Lighthousse Healthcare Ltd | Harlow | 2026 |
| 3D Marcomms Holdings Limited | Chelmsford, Essex | 2022 |
| 3D Marcomms Limited | Chelmsford | 2008 |
| 3D Metrology Leasing Limited | Coventry | 2018 |
| 3D Minds Limited | Ilford | 2014 |
| 3D Nexus Limited | London | 2000 |
| 3D OBA Services Ltd | Gillingham | 2025 |