| 5 Consultancy Limited | Oldbury | 2007 |
| 5 Consulting Limited | Lydney | 2004 |
| 5 Cyril Crescent Management Limited | Cardiff | 2006 |
| 5 D Design Ltd | Belfast | 2018 |
| 5 Day Photography School Ltd | London | 2024 |
| 5 DG Limited | Goole | 2012 |
| 5 E Consulting Ltd | Pinner | 2012 |
| 5 Health Holdings Ltd | Manchester | 2018 |
| 5 Horizons Consulting Limited | Cambridge | 2021 |
| 5 Jerningham Road Freehold Limited | London | 2021 |
| 5 Leaf Clover Consultants Limited | Steyning | 2025 |
| 5 Lights Private Limited | Bradford | 2023 |
| 5 Limited | Brighton | 2002 |
| 5 Lions Consortium Limited | Luton | 2025 |
| 5 Marlborough Buildings Bath Limited | Bristol | 1965 |
| 5 Moat Street Opco Limited | London | 2022 |
| 5 Moat Street Propco Limited | London | 2019 |
| 5 Moments Executive Leadership Limited | Chesterfield | 2014 |
| 5 Oceans Partnership Ltd | Weybridge | 2016 |
| 5 Oceans Subsea Ltd | Aberdeen | 2012 |
| 5 Oceans Yacht Management Ltd | Trowbridge | 2025 |
| 5 Orange Ltd | London | 2026 |
| 5 OUT Consulting Limited | Rochester | 2021 |
| 5 Part Consulting Limited | Swindon | 2026 |
| 5 PC Coffee Company Limited | Glasgow | 2020 |
| 5 Phase Ltd | London | 2025 |
| 5 PIN Lighting Ltd | Cranbrook | 2025 |
| 5 Point Five Limited | Salford | 2014 |
| 5 Points Trading Ltd | London | 2022 |
| 5 Rhino Consulting Ltd | Headington | 2021 |
| 5 Richmond Limited | London | 2025 |
| 5 Rights Ltd | London | 2022 |
| 5 Rivers Accountancy Ltd | London | 2015 |
| 5 Rosary Gardens Limited | Ashford | 2006 |
| 5 Senses Interiors Limited | London | 2024 |
| 5 SJR Limited | Burgess Hill | 2020 |
| 5 Spice Marketing Ltd | Kidderminster | 2019 |
| 5 ST Andrews Road Kingsbury Limited | London | 1998 |
| 5 Star Consultancy BW Ltd | Ruthin | 2023 |
| 5 Star HR Solutions Limited | Birmingham | 2016 |
| 5 Star PR Ltd | Newcastle Upon Tyne | 2014 |
| 5 Star School Photography Ltd | Sutton-In-Ashfield | 2026 |
| 5 Star Solutions Ltd | Southam | 2019 |
| 5 Star Surveying Ltd | London | 2023 |
| 5 Star Weddings Ltd | Bridgend | 2018 |
| 5 Stones Ltd | Bristol | 2020 |
| 5 Style Ltd | Edinburgh | 2014 |
| 5 Topads Ltd | Glasgow | 2025 |
| 5 Tracks Business Coaching Ltd | Leeds | 2018 |
| 5 Westbourne Villas (Hove) Limited | Hove | 2005 |
| 5 Why's Consulting Ltd | Dewsbury | 2016 |
| 5 Windsor Terrace (Whitby) Limited | Whitby | 2006 |
| 5 York Avenue Limited | Hove | 2013 |
| 5, Bina Gardens Limited | London | 1986 |
| 5-7 Cranbrook Drive Limited | Hertfordshire | 2000 |
| 5-8 Dudley Close Limited | Chafford Hundred | 2001 |
| 5-BY-5 Associates Ltd | Waterlooville | 2013 |
| 5.23 Ltd | London | 2011 |
| 50 Belsize Park Gardens Limited | | 1987 |
| 50 Belsize Park Management Limited | | 1989 |
| 50 Brook Green Management Company Limited | London | 1999 |
| 50 Degrees North Design Consultants Limited | Huddersfield | 2006 |
| 50 Green Ltd | Wolverhampton | 2018 |
| 50 Interior Studio Ltd | Aberdeen | 2024 |
| 50 Molesworth Road Management Company Limited | Plymouth | 1989 |
| 50 Montague Road Management Company Limited | | 1990 |
| 50 Percent Ltd | London | 2018 |
| 50 Pound Social Ltd | Leeds | 2016 |
| 50 West Street Management Company Limited | Salisbury | 2019 |
| 50 Woodstock Grove Limited | London | 2015 |
| 50+HEALTH Ltd | Hereford | 2000 |
| 50,000 Feet Consulting Ltd | Derby | 2019 |
| 50.01 Production & Communication Limited | Brentford | 2014 |
| 50/50 Architectural Services Limited | Londonderry | 2008 |
| 50/50 Events Ltd | Hull | 2018 |
| 500 Jigsaw Limited | Apethorpe | 2018 |
| 500 Miles Limited | London | 2018 |
| 500 Words Ltd | Wilmslow | 2014 |
| 5000 Ltd | Edinburgh | 2020 |
| 5001 Capital Limited | London | 2024 |
| 5002 Consulting Ltd | Richmond | 2024 |
| 50026 Restoration Group Limited | Wantage | 1994 |
| 502118 Limited | Dorking | 2022 |
| 505 Commercial Services Ltd | Stourport-On-Severn | 2026 |
| 505 Digital Ltd | Lancing | 2020 |
| 505 Group Limited | Bristol | 2021 |
| 5050HEALTH.COM Ltd | Cannock | 2025 |
| 507CLIMATE Solutions Ltd | London | 2026 |
| 508 Ventures Limited | Bolton | 2024 |
| 50:50 Future Ltd | Sheffield | 2019 |
| 50FT Ltd | London | 2024 |
| 50THRIVE Ltd | Salford | 2026 |
| 51 Brayburne Avenue Limited | | 2004 |
| 51 Dean Lane Management Company Limited | Bristol | 2006 |
| 51 Degrees Above Ltd | Rochester | 2018 |
| 51 Degrees North Studios Limited | Bingley | 2014 |
| 51 Degrees Production Services Ltd | Surbiton | 2021 |
| 51 Desborough Ltd | London | 2023 |
| 51 Dominance Capital Limited | Cardiff | 2021 |
| 51 Eastdown Park Limited | | 1999 |