| Assemble Skills Ltd | London | 2025 |
| Assemble YOU Limited | Birmingham | 2021 |
| Assembly Agency Limited | Wakefield | 2026 |
| Assembly of GOD Ministry GOD IS Faithful Ltd | Oxford | 2022 |
| Assero Training Solutions Limited | Cardiff | 2023 |
| Assertive Mentoring Limited | Stockton On Tees | 2015 |
| Asservio Limited | Crewe | 2013 |
| Asses Team Ltd | London | 2024 |
| Assess & EDU Ltd | London | 2018 |
| Assess 4 Success Tuition Ltd | Nottingham | 2020 |
| Assess Assist Limited | Shrewsbury | 2014 |
| Assess Education Limited | Liverpool | 2009 |
| Assessed Education Limited | Nottingham | 2010 |
| Assessify Limited | Stockton On Tees | 2009 |
| Assessment & Training Nerac Limited | Barnsley | 2006 |
| Assessment and Professional Recognition Body (Aprb) Ltd | London | 2022 |
| Assessment and Qualifications Alliance Limited | Manchester | 2012 |
| Assessment and Training Services Ltd | Thorpe Willoughby | 2004 |
| Assessment Associates Limited | Stockport | 2017 |
| Assessment Centre Training Ltd. | Longfield | 2013 |
| Assessment Counts Ltd | Gloucester | 2015 |
| Assessment Hub Ltd | London | 2023 |
| Assessment in Clinical Education Ltd | London | 2024 |
| Assessment Works Ltd | Stockton-On-Tees | 2025 |
| ASSESSMENT360 Limited | Birmingham | 2021 |
| Assessprogress.Com Ltd | Oxford | 2022 |
| Asset Academy Ltd | Watford | 2019 |
| Asset Acquisition Group Limited | London | 2024 |
| Asset Education | Ipswich | 2015 |
| Asset English Ltd | Wallasey | 2020 |
| Asset Finance Academy Ltd | London | 2026 |
| Asset Management International Limited | London | 2017 |
| Asset Networks Holdings Limited | Derby | 2018 |
| Asset Networks Limited | Derby | 1999 |
| Asset Training Limited | Norfolk | 2007 |
| Asset Wisdom Limited | Tadcaster | 2013 |
| Assets Insights Ltd | Dartford | 2026 |
| Assi Consultancy Ltd | London | 2020 |
| Assisi Catholic Trust | Westcliff On Sea | 2011 |
| Assist & Empower Ltd | London | 2024 |
| Assist Education Ltd | Orpington | 2021 |
| Assist Learning Limited | Enfield | 2016 |
| Assist the Learner Driver Ltd | Walsall | 2020 |
| Assist Tutor Limited | London | 2019 |
| Assist'Em Limited | Par | 2004 |
| Assist-Uk Ltd | Northampton | 2025 |
| Assistance Dogs (Adni) | Limavady | 2021 |
| Assisted Days OUT Limited | Bolton | 2021 |
| Assisted Reading for Children | Bicester | 2012 |
| Assistive IOT Ltd | Oswestry | 2018 |
| Assistive Tuition Limited | Ramsgate | 2018 |
| Assn. of Colleges and Business Schools Limited | London | 2025 |
| Associate Management Systems Limited | London | 2017 |
| Associated Community Training Limited | Cardiff | 1988 |
| Associated Trainers Ltd | Colchester | 2002 |
| Associated Training Services (ATS) Ltd | Tadley | 2021 |
| Association "Moveup" CIC | Exeter | 2025 |
| Association for Accredited Learning CIC | Altrincham | 2017 |
| Association for Character Education Limited | Birmingham | 2016 |
| Association for Clinical Theological Training and Care Limited(The) | Redhill | 1962 |
| Association for Cultural Advancement Through Visual Art | | 1983 |
| Association for Cultural Exchange Limited(The) | Cambridge | 1958 |
| Association for Industrial Archaeology | Telford | 1977 |
| Association for Infant Mental Health (U.K.) | Chipping Campden | 1996 |
| Association for Jewish Youth Incorporated(The) | London | 1951 |
| Association for Learning Environments Limited | Leicester | 2011 |
| Association for Physical Education | Worcester | 2005 |
| Association for Reaching & Instructing Children in Africa | Norwich | 1999 |
| Association for Simulated Practice in Healthcare | Lichfield | 2013 |
| Association for the History of Glass, Limited(The) | London | 1978 |
| Association for the Understanding of Artificial Intelligence | Bristol | 2019 |
| Association of Global Lawyers | London | 2019 |
| Association of Accessible Employers CIC | Helston | 2021 |
| Association of Adult Education and Training Organisations | Evesham | 2010 |
| Association of Afghan United in Britain | Leicester | 2010 |
| Association of Apprentices | Nottingham | 2019 |
| Association of British Dispensing Opticians(The) | Canterbury | 1986 |
| Association of British Muslims C.I.C. | Bilston | 2019 |
| Association of British Schools Overseas | Hemel Hempstead | 2019 |
| Association of Calypsonians and Soca Artistes Ltd. | London | 2015 |
| Association of Certified Digital Accounting Professionals | London | 2019 |
| Association of Certified Digital Accounting Technicians | London | 2020 |
| Association of Certified Entrepreneurs (UK) | Stockton-On-Tees | 2011 |
| Association of Certified Professional Managers Limited | London | 2015 |
| Association of Chinese Teachers in the UK | London | 2019 |
| Association of Christians in Counselling and Linked Professions | London | 1993 |
| Association of Construction Trainers CIC | Bedford | 2023 |
| Association of Coordinators for Erasmus+ UK Ltd | Edinburgh | 2026 |
| Association of Education Advisers | Newcastle Upon Tyne | 2018 |
| Association of Education Business Professionals C.I.C. | Rotherham | 2018 |
| Association of Financial Accountants | London | 2015 |
| Association of International Certified Digital Accountant | London | 2020 |
| Association of International Certified Professional Accountants (UK) | London | 2016 |
| Association of International Education | Kington | 2020 |
| Association of Iranian Athletes for Freedom CIC | London | 2026 |
| Association of Marine Electronic & Radio Colleges Limited | Kendal | 1997 |
| Association of Marketing Facilitators CIC | Leeds | 2024 |
| Association of Multicultural Communities UK | London | 1991 |
| Association of Muslim Schools, UK | Luton | 2003 |
| Association of Muslim Supplementary Schools | Luton | 2010 |