| 4 Nurses Limited | Stafford | 2024 |
| 4 Orchids Ltd | Doncaster | 2024 |
| 4 Pharm Limited | Slough | 2007 |
| 4 Pillars ACP Locum Services Ltd | Wirral | 2022 |
| 4 Pillars Housing Ltd | Leicester | 2024 |
| 4 Season Care Ltd | Berkshire | 2014 |
| 4 Seasons Medical Centre Ltd | Warrington | 1998 |
| 4 Sisters Care Ltd | Birmingham | 2018 |
| 4 Sisters UK Limited | London | 2022 |
| 4 Society Ltd | Lincoln | 2011 |
| 4 Star Care Services Ltd | Rochdale | 2017 |
| 4 Ways Healthcare Limited | Hemel Hempstead | 2003 |
| 4 Winds User LED Association | Cardiff | 1998 |
| 4 Xray Ltd | Norwich | 2025 |
| 4 YOU Care Ltd | Plymouth | 2020 |
| 4 YOU Reablement and Support Limited | Grantham | 2019 |
| 4 Your Eyes Ltd | Leicester | 2005 |
| 4-ARMED Health Ltd | Woodford Green | 2020 |
| 4-CARE Recruitment Limited | Aberdeen | 2025 |
| 4-D Specialist Services Limited | Chippenham | 2017 |
| 40/40 Healthcare Limited | Belfast | 2015 |
| 402 Limited | Nottingham | 2011 |
| 4036 HC Ltd | London | 2024 |
| 406 Dental Limited | Ellesmere Port | 2023 |
| 41 South Limited | Borehamwood | 2025 |
| 41 the Headrow Limited | Leeds | 2003 |
| 42 Aberdare Gardens Limited | London | 2003 |
| 42ASHBOURNE Limited | London | 2017 |
| 42ND Street - Community Based Resource for Young People Under Stress | Manchester | 1990 |
| 43 Group Ltd | Witney | 2025 |
| 4319 Fountain Care Ltd | Uxbridge | 2014 |
| 43CP Limited | London | 2025 |
| 44 Fruits Limited | Mitcham | 2011 |
| 44 Housing and Care Support Services Ltd | Bury St. Edmunds | 2022 |
| 444 Dental Ltd | Watford | 2020 |
| 45 Core Solutions Limited | Leicester | 2025 |
| 456 RG Ltd | Glasgow | 2025 |
| 45GT Ltd | London | 2025 |
| 46 Melgund Road Limited | Highbury | 2006 |
| 46 Phillin Limited | Watford | 2007 |
| 4646CARING Ltd | Romford | 2023 |
| 4646LOCUM Ltd | Romford | 2023 |
| 4646MEDICAL Ltd | Romford | 2023 |
| 465 Valleys Healthcare Ltd | Tredegar | 2020 |
| 47 Degrees Limited | Maidenhead | 2018 |
| 470NM Limited | Harrow | 2022 |
| 48 Carat Ltd | Cardiff | 2018 |
| 48 Dawlish Holdings Ltd | Birmingham | 2025 |
| 4A Dental Surgery Ltd | York | 2009 |
| 4A Medics Limited | Leeds | 2023 |
| 4AE Limited | Hassocks | 2023 |
| 4AGM Ltd | London | 2021 |
| 4ALL - Building Community in West Dulwich | London | 2010 |
| 4AS Care Services Limited | Bromsgrove | 2022 |
| 4BETA Limited | London | 2016 |
| 4C Clinical Ltd | Folkestone | 2014 |
| 4CANHOTO Limited | Altrincham | 2011 |
| 4CH Care Ltd | London | 2026 |
| 4COURT Healthcare Limited | Blackburn | 2010 |
| 4D Baby and Fertility Scans Ltd | Northampton | 2026 |
| 4D Care Limited | Ely | 2002 |
| 4D Global Healthcare Services Ltd | Manchester | 2021 |
| 4D Medical Ltd | Newark | 2014 |
| 4D Ohenebeng Limited | Stevenage | 2016 |
| 4D Therapy Ltd | Hope Valley | 2019 |
| 4DEXTERITY Limited | Sheffield | 2019 |
| 4DS Healthcare Ltd | London | 2019 |
| 4EF Ltd | London | 2016 |
| 4ENSICMED Ltd | Harrow | 2011 |
| 4EVER Care Home Ltd | London | 2025 |
| 4EVER Smiles Ltd | Bridgend | 2024 |
| 4EYE Spec Ltd | Coventry | 2013 |
| 4EYES Optical Ltd | Harrow | 2018 |
| 4FS & PEE Limited | Exeter | 2025 |
| 4GP Health Limited | Ilford | 2023 |
| 4HH Limited | Blackburn | 2015 |
| 4INSTA Care Ltd | Downpatrick | 2024 |
| 4J'S Services Limited | Cheadle | 2018 |
| 4K Footcare Services Ltd | Bury St. Edmunds | 2022 |
| 4K Occupational Therapy Services Ltd | Westgate-On-Sea | 2011 |
| 4K5H4T Ltd | Huddersfield | 2023 |
| 4KIDSVISION Ltd | Newcastle Upon Tyne | 2023 |
| 4KIDZ Childcare Ltd | Hemel Hempstead | 2015 |
| 4KV Health Care Ltd | Chertsey | 2020 |
| 4LAVA Limited | Warrington | 2022 |
| 4LEGACY Limited | Forest Gate | 2023 |
| 4LIFE Care Services Limited | Manchester | 2021 |
| 4LIFE Healthcare Limited | Carlisle | 2017 |
| 4LIFE Healthcare Services Limited | Canterbury | 2016 |
| 4M Care Limited | Sheffield | 2025 |
| 4M Fit Ltd | Bishops Stortford | 2022 |
| 4M Mentor Mothers Network CIC | London | 2019 |
| 4M Partners Limited | Durham | 2023 |
| 4MC Limited | London | 2023 |
| 4ME&U Ltd | Plymouth | 2014 |
| 4MED Limited | Shrewsbury | 2011 |
| 4MINDHEALTH Ltd | Kington | 2023 |
| 4MK Ltd | Billingshurst | 2025 |
| 4MOST Fitness Ltd | Liverpool | 2013 |
| 4MOST Healthcare Limited | Flint | 2023 |