| Assidere Limited | Teignmouth | 2023 |
| Assign Medicare Limited | Birmingham | 2011 |
| Assigned Healthcare Solutions Limited | Peterborough | 2023 |
| Assim Dermatology Ltd | Bedford | 2021 |
| Assini Limited | Canterbury | 2012 |
| Assirklann Ltd | Northampton | 2016 |
| Assisprac Ltd | Watford | 2023 |
| Assist 7 Days Ltd | Nottingham | 2016 |
| Assist and Care Limited | Stockport | 2010 |
| Assist Care Agency Limited | Worthing | 2003 |
| Assist Care and Support Ltd | Bathgate | 2016 |
| Assist Care Group Limited | Cranleigh | 2018 |
| Assist Care Ltd | Coventry | 2023 |
| Assist Care Service Co Limited | Cranleigh | 1994 |
| Assist Care Team Limited | Northampton | 2012 |
| Assist Domiciliary Care Limited | Leeds | 2012 |
| Assist Eyecare Limited | Woking | 2015 |
| Assist GP Limited | Romney Marsh | 2023 |
| Assist Healthcare Ltd | Sheffield | 2025 |
| Assist Home Care Ltd | Bradford | 2009 |
| Assist Pharmacist Locums Limited | Stockport | 2022 |
| Assist Plus Care Ltd | Hayes | 2024 |
| Assist to Grow Limited | Enfield | 2022 |
| Assist Trust | Norwich | 1996 |
| Assistants at Hand (South West) Ltd | Plymouth | 2015 |
| Assisted Assessments Ltd | Folkestone | 2024 |
| Assisted Care Services Limited | Northampton | 2017 |
| Assisted Homecare Ltd | Cardiff | 2021 |
| Assisted Independence Ltd | Bonnyrigg | 2023 |
| Assisted Individuals Respite and Care Ltd | Barnstaple | 2018 |
| Assisted Lives Gloucester Ltd | Bradford | 2024 |
| Assisted Lives Ltd | Bradford | 2011 |
| Assisted Lives Worcester Ltd | Bradford | 2024 |
| Assisted Living Care Group Ltd | Northampton | 2019 |
| Assisted Living Care Ltd | Northampton | 2021 |
| Assisted Living Home Care Limited | Caerphilly | 2022 |
| Assisted Living Services (Kent) Limited | Ramsgate | 2014 |
| Assisted Living Solutions Limited | Coventry | 2003 |
| Assisted Living South West (Propco) Limited | Coventry | 2008 |
| Assisted Living South West Limited | Birmingham | 2008 |
| Assisted Medicare Services Limited | Loughborough | 2023 |
| Assisted Mobility Services Limited | Maesteg | 2018 |
| Assisted Services (Fife) Limited | Kirkcaldy | 2022 |
| Assisting Angels Care Ltd | Reading | 2024 |
| Assisting Families With Information and Resources on Migration for Sustainability Ltd. | London | 2013 |
| Assistium Limited | Lutterworth | 2018 |
| Assistium Recruitment Ltd | Lutterworth | 2023 |
| Assistiva Care Ltd | Birmingham | 2024 |
| Assistive Technology Solutions Ltd | Barnsley | 2025 |
| Assistkidz Ltd | Bangor | 2019 |
| Assistvalley Care Ltd | London | 2026 |
| Assistwide Limited | Merseyside | 1992 |
| Assk Ltd | Dunstable | 2018 |
| Assk Medical Solutions Ltd | Birmingham | 2020 |
| Associate Cares Ltd | Plymouth | 2019 |
| Associate Health Ltd | Bury | 2021 |
| Associate Therapists Ltd | Preston | 2011 |
| Associated Addiction Services Ltd | Birmingham | 2026 |
| Associated Care Services Ltd | London | 2009 |
| Associated Care Solutions Limited | Swindon | 2010 |
| Associated Therapy Services Limited | Sheffield | 2001 |
| Associates Healthcare Community Interest Company | Croydon | 2018 |
| Association for Cognitive Analytic Therapy | Dorchester | 2007 |
| Association for Counselling and Therapy Online Ltd | London | 2017 |
| Association for Family and Systemic Psychotherapy Ltd | Warrington | 1995 |
| Association for Glycogen Storage Disease (UK) Limited | Oldbury | 2009 |
| Association for Group and Individual Psychotherapy | | 1999 |
| Association for Practice Based Approach | Hartlepool | 2012 |
| Association for Relief and Medical AID | | 1990 |
| Association for Spinal Injury Research Rehabilitation and Reintegration | Stanmore | 1999 |
| Association for Women's Awareness and Rural Development (Award), UK C.I.C. | Salford | 2024 |
| Association International Tamils CIC | Ilford | 2023 |
| Association of Air Ambulances (Charity) Ltd | 46 The Priory Queensway | 2015 |
| Association of Ayurvedic Professionals UK | South Croydon | 2017 |
| Association of Camerados Community Interest Company | Birmingham | 2018 |
| Association of Casualty and Health Emergency Simulators | Kent | 1996 |
| Association of Community and Multibed Acupuncture Clinics, C.I.C. | Uckfield | 2013 |
| Association of Cosmetic Practitioners in Britain Limited | Salford Quays | 2014 |
| Association of God's Heritage Provision for Children Ltd | Chatham | 2018 |
| Association of Health Care Professionals Limited | London | 2016 |
| Association of Hypnotherapy and Stress Management Limited | Evesham | 1999 |
| Association of Jungian Analysts Limited | London | 1977 |
| Association of Natural Medicines Limited | Essex | 1983 |
| Association of Naturopathic Practitioners | Forest Row | 2001 |
| Association of Nigerian Social Workers United Kingdom C.I.C. | Harlow | 2021 |
| Association of Ophthalmic Nurses and Technicians (UK) Ltd | Blandford Forum | 1970 |
| Association of Optometrists | London | 1946 |
| Association of Respiratory Nurses | Lichfield | 2019 |
| Association of South Asian Midwives C.I.C. | Manchester | 2020 |
| Association of Ukrainians in Great Britain Limited(The) | | 1947 |
| Association of Zimbabwean Pharmacists Abroad CIC | Wilmslow | 2021 |
| Assos Medical & Surgical Ltd | Mumbles | 2019 |
| Assos Vision Ltd | Swansea | 2026 |
| Assumpta Care Limited | Nottingham | 2022 |
| Assumpta Care Services Limited | London | 2022 |
| Assumpta Limited | Taunton | 2024 |
| Assumptar Limited | London | 2021 |
| Assurance Care Services Limited | Croydon | 2010 |
| Assure Care Homes Ltd | Southampton | 2014 |
| Assure Care Ltd | Milton Keynes | 2013 |