| Activhealth Ltd | Nuneaton | 2022 |
| Actiview Optics Ltd | Birmingham | 2018 |
| Activist Doctor Limited | Fleetwood | 2026 |
| Activities 4 Kids Ltd | Shoreham-By-Sea | 2018 |
| Activities 4 U | London | 2013 |
| Activities and Wellbeing Limited | Dudley | 2022 |
| Activities for YOU C.I.C. | Denbigh | 2022 |
| ACTIVITIS4KIDS Limited | Cardiff | 2020 |
| Activity Angels CIC | Warrington | 2024 |
| Activity Care Ltd | Liverpool | 2020 |
| Activity Care NW Ltd | Liverpool | 2026 |
| Activity Carers Agency Ltd | Chester | 2018 |
| Activlives | Ipswich | 2011 |
| Activliving Physiotherapy Ltd | Preston | 2023 |
| Activo Care Limited | Birmingham | 2018 |
| Activology C.I.C. | Tamworth | 2018 |
| Activrehab Ltd | Bedford | 2026 |
| Acton Banks Home Care Ltd | Wolverhampton | 2020 |
| Acton HIP and Knee Consultant Ltd | Derry | 2014 |
| Acton Homeless Concern (Emmaus House and Damien Centre) | | 1996 |
| Acton Lane Medical Centre Limited | Isleworth | 2020 |
| Acton Medical Services Limited | London | 2018 |
| Acton Mill Support Limited | Worcester | 2011 |
| Acton PCN Limited | London | 2023 |
| Acton Wrap Around Care Ltd | Bury St. Edmunds | 2022 |
| Actors' Benevolent Fund(The) | | 1929 |
| Actros 74 Ltd | Epsom | 2019 |
| Acts 435 | York | 2009 |
| Acts Community Church | Tylorstown | 2010 |
| Acts Health Care Ltd | Stafford | 2016 |
| Acts in Action CIC | Nottingham | 2024 |
| Actscp Ltd | Welling | 2024 |
| Actseen Limited | Mid-Glamorgan | 1983 |
| Actual Care Services Ltd | Birmingham | 2017 |
| Actual First AID Limited | Coventry | 2023 |
| Actual Potential Ltd | Gainsborough | 2026 |
| Actualise Counselling and Therapy Ltd | Nottingham | 2026 |
| Actualising U! Ltd | South Croydon | 2021 |
| Actualize Wellbeing CIC | Norwell | 2018 |
| Actualizing Ltd | Reading | 2022 |
| ACU & Herbs Limited | London | 2009 |
| ACU and EAR Care Services Ltd | London | 2026 |
| ACU Facial Limited | Hertford | 2012 |
| ACU Herbs Health Limited | Maidenhead | 2021 |
| ACU Land Limited | Maidenhead | 2022 |
| ACU Peace CIC | Prenton | 2021 |
| ACU Productions Ltd | Hamilton | 2026 |
| ACU Spirit Limited | Nottingham | 2018 |
| Acu-Herbs Health Care Limited | Ruislip | 2005 |
| Acu-Star Limited | Lytham St. Annes | 2009 |
| Acu:East Ltd | Frome | 2017 |
| Acuaware Ltd | Folkestone | 2024 |
| Acuba Care Limited | London | 2023 |
| Acuba Fostering Limited | London | 2024 |
| Acubody Ltd | London | 2011 |
| Acubody Moves Ltd | London | 2023 |
| Acucare for Life Limited | Manchester | 2023 |
| Acucare&Herbal Ltd | Swindon | 2020 |
| Acuda Medicare Limited | Sutton Coldfield | 2021 |
| Acudoc Limited | Gillingham | 2012 |
| Acufy Limited | Maldon | 2024 |
| Acuheal Limited | Middlesex | 2002 |
| Acuhealth Clinic Ltd | Sale | 2018 |
| Acuhealth Limited | Burton-On-Trent | 2003 |
| Acuherb TCM Ltd | Leicester | 2026 |
| Acuherbs & Spa UK Limited | Bromley | 2018 |
| Acuherbs Clinic Limited | York | 2023 |
| Acuherbs Limited | Birmingham | 1999 |
| Acuimetry Ltd | Chatham | 2025 |
| Acuity Counselling Ltd | Colchester | 2024 |
| Acuity Direct Ltd | Oldham | 2022 |
| Acuity Hearing Limited | Ebbw Vale | 2018 |
| Acuity Optical Ltd | Bradford | 2023 |
| Acuity Optics Ltd | Cockfosters | 2009 |
| Acuitycare Limited | Wakefield | 2023 |
| Aculate Consultancy Ltd | Feltham | 2025 |
| Aculife Limited | Oxford | 2017 |
| Aculing Ltd | Walthamstow | 2018 |
| Aculymph Clinic Ltd | London | 2026 |
| Acumen Clinical Services, Research and Innovation Ltd | Warrington | 2022 |
| Acumen Medical Limited | Axminster | 2009 |
| Acumen Medicolegal Ltd | Buckhurst Hill | 2024 |
| Acumentice Ltd | London | 2014 |
| Acuminds CIC | Darwen | 2026 |
| Acunutrition Limited | Letchworth Garden City | 2003 |
| Acuo Ltd | Warrington | 2015 |
| Acuphysio Care Ltd | Feltham | 2024 |
| Acuphysio Limited | Usk | 2025 |
| Acupips Ltd | Holmfirth | 2021 |
| Acupro Limited | London | 2016 |
| Acupuncture & Health Centre Ltd | Edinburgh | 2010 |
| Acupuncture & Herbal Limited | London | 2017 |
| Acupuncture & Herbs Limited | Warrington | 2002 |
| Acupuncture & Homoeopathic Clinic Ltd | Harrow | 2014 |
| Acupuncture 1ST Limited | St. Albans | 2015 |
| Acupuncture and Medical Massage Limited | London | 2012 |
| Acupuncture and Rehab Clinic Limited | Retford | 2024 |
| Acupuncture China Limited | Southampton | 2017 |
| Acupuncture Health Limited | Glasgow | 2025 |
| Acupuncture Healthcare Limited | Dunstable | 2025 |