| 2XN Limited | London | 2017 |
| 2XP Ltd | Manchester | 2021 |
| 2XPD8 Limited | Weymouth | 2002 |
| 2XPRESSO Ltd | London | 2025 |
| 2XROI Ltd | London | 2024 |
| 2XSM Consulting Limited | Stowmarket | 2023 |
| 2Y3X Consulting (UK) Limited | London | 2020 |
| 2YE Limited | Northampton | 2023 |
| 3 & Lime Design Ltd | Guildford | 2010 |
| 3 -5 Drysdale Street Management Co Limited | Saffron Walden | 2002 |
| 3 10 Studio Ltd | Bristol | 2014 |
| 3 6 & 7 Westcombe Park (Heybridge) Management Company Limited | Hemel Hempstead | 2024 |
| 3 Acres Group Ltd | Aylesbury | 2023 |
| 3 Active (CFS) Limited | Shillington | 2015 |
| 3 Albion Terrace Management Company Limited | Saltburn-By-The-Sea | 2010 |
| 3 and 3A Albion Road Management Limited | Caterham | 2004 |
| 3 and a Half Geniuses Ltd | London | 2014 |
| 3 Automotive Group Limited | Blaydon-On-Tyne | 2025 |
| 3 Bathwick Street (Bath) Limited | Avon | 1979 |
| 3 Bear Ventures Ltd | Thames Ditton | 2024 |
| 3 Bears Law Limited | Nottingham | 2021 |
| 3 Bears Payroll Consultancy Ltd | London | 2025 |
| 3 Best Friends Limited | London | 2012 |
| 3 Birch House Ltd | Cardiff | 2000 |
| 3 Blade Consultants Ltd | Altrincham | 2024 |
| 3 Borders Limited | Corby | 2013 |
| 3 Bridges Vets Limited | Dunfermline | 2020 |
| 3 Bright Minds Consulting Limited | Wimbledon | 2010 |
| 3 Brown Bears Ltd | Blairgowrie | 2025 |
| 3 Byte Limited | Liverpool | 2010 |
| 3 C + 1 Limited | Milton Keynes | 2001 |
| 3 C C London Group Limited | Epsom | 2026 |
| 3 Caret Limited | Preston | 2014 |
| 3 Central Avenue (West Bridgford) UK Limited | Nottingham | 2011 |
| 3 Chillies Studio Limited | London | 2025 |
| 3 Circles Management Ltd | Maldon | 2025 |
| 3 College Fields Management Company Limited | Bristol | 2014 |
| 3 Cord Limited | London | 1996 |
| 3 Cords Communications Ltd | London | 2026 |
| 3 Counties Energy Assessments Limited | Doncaster | 2007 |
| 3 Counties Holistic Healthcare Limited | Worcester | 2007 |
| 3 Counties Surveying Limited | Bath | 2019 |
| 3 County Accounts Ltd | Liphook | 2026 |
| 3 County Group Ltd | Gillingham | 2015 |
| 3 Cousins Agency Ltd | St. Albans | 2025 |
| 3 CS Solutions Ltd | Edenbridge | 2024 |
| 3 D Technical Services Limited | Whitchurch | 2009 |
| 3 DEN Crescent Management Limited | Devon | 1994 |
| 3 Design Scotland Limited | Glasgow | 2016 |
| 3 Dimensional Concepts Ltd | Coatbridge | 2013 |
| 3 Dimensional Projects Ltd | London | 2010 |
| 3 DOC Locums Limited | Preston | 2026 |
| 3 Dots Capital Advisory Ltd | London | 2023 |
| 3 Dots Deep Limited | Crieff | 2018 |
| 3 Dots Talent Ltd | Brighton | 2019 |
| 3 Dragon Marketing Ltd | St. Albans | 2010 |
| 3 Dream Labs Limited | Herne Bay | 2019 |
| 3 Durham Terrace Limited | London | 2001 |
| 3 ED Holdings 2 Limited | Edinburgh | 2007 |
| 3 Faces Recruitment Limited | Rotherham | 2017 |
| 3 Farrant Limited | | 2006 |
| 3 Five Consulting Limited | Stoke-On-Trent | 2010 |
| 3 Flags Ltd | London | 2017 |
| 3 Floors High Limited | Kettering | 2021 |
| 3 Flow Creative Ltd | Brighton | 2012 |
| 3 Focus Marketing Ltd | Bromley | 2023 |
| 3 Fold Strategem Limited | Belper | 2012 |
| 3 Form Consulting Ltd | London | 2020 |
| 3 G Legal Ltd | Brierley Hill | 2021 |
| 3 Gracias Limited | London | 2018 |
| 3 Green Lights Ltd | Oxford | 2022 |
| 3 Grove Avenue Residents Association Limited | Kent | 1991 |
| 3 Hand Design Limited | Stroud | 2016 |
| 3 Hares Clinic Ltd | Tarporley | 2012 |
| 3 Heads Limited | Bedford | 2017 |
| 3 Hills Ltd | Taunton | 2019 |
| 3 Hours West Limited | Bridport | 2010 |
| 3 I Training Limited | Bourne | 1999 |
| 3 J'S Enterprises Limited | Carmarthen | 1998 |
| 3 J'S Surveyors & Valuers Limited | Hove | 2006 |
| 3 J'S Telecomms Limited | Reading | 2013 |
| 3 Kats Limited | Harpenden | 2017 |
| 3 Lancaster Buildings Ltd | Penarth | 2015 |
| 3 Legal Ltd | Huddersfield | 2019 |
| 3 Leighton Crescent Limited | London | 1990 |
| 3 Leysfield Road Management Company Ltd. | London | 1998 |
| 3 Limited | South Croydon | 1997 |
| 3 Lines of Defence Consulting Limited | London | 2014 |
| 3 Lines of Defence Group Limited | London | 2019 |
| 3 Lines of Defence Limited | London | 2019 |
| 3 Little Birds Finance Ltd | Bury St. Edmunds | 2022 |
| 3 Little GS Ltd | Glasgow | 2025 |
| 3 Little Steps Ltd | Southampton | 2010 |
| 3 Mads UK Limited | Reading | 2025 |
| 3 Magic Monkeys Limited | Ruislip | 2008 |
| 3 Match Consulting Limited | Westerham | 2012 |
| 3 Media Limited | Blackpool | 2011 |
| 3 MEN and a Wooden Spoon Limited | Harrow | 2024 |
| 3 Mile Ltd | Gosport | 2022 |
| 3 Minute Mile Ltd | London | 2006 |