| Association of Nanny Agencies Limited | London | 2022 |
| Association of National Accountants of Nigeria (Anan) UK Branch | London | 2024 |
| Association of NET Zero Installers | London | 2025 |
| Association of NHS Charities | Warwick | 2019 |
| Association of Nigerian Academics UK | London | 2010 |
| Association of Northern Mediators | Leeds | 2012 |
| Association of Northern Scaffolding Contractors | Southport | 2003 |
| Association of Old Vehicle Clubs in Northern Ireland Limited - the | Co Down | 1979 |
| Association of Online Publishers Limited | London | 2009 |
| Association of Pakistani Physicians of Northern Europe Limited | Rochester | 2017 |
| Association of Pensions & Benefits Claimants CIC | Colchester | 2012 |
| Association of Personal Injury Lawyers | Nottingham | 1994 |
| Association of Planning Engineers Limited | Guildford | 2020 |
| Association of Professional BIT and Bridle Fitters | London | 2021 |
| Association of Professional Declutterers and Organisers | Chester | 2022 |
| Association of Professional Pension Trustees Limited | Wokingham | 2012 |
| Association of Professional Shooting Instructors Ltd | Ashbourne | 2017 |
| Association of Professional Virtual Assistants Limited | Grimsby | 2020 |
| Association of Professional Wedding Engagement Coordinators of Nigeria (Apwecon) UK Chapter Ltd | London | 2021 |
| Association of Property Buyers (National) Limited | Worthing | 2014 |
| Association of Public Analysts(The) | London | 1953 |
| Association of Railway Training Providers Ltd | Derby | 1989 |
| Association of Recruitment Marketing Agencies Limited | Harrow | 2024 |
| Association of Reflexologists | Taunton | 2005 |
| Association of Related Churches (Ireland) | Belfast | 2014 |
| Association of Renal Industries Ltd | Thatcham | 2006 |
| Association of Russian Ballet and Theatre Arts Ltd | Little Barford | 2022 |
| Association of Scottish Visitor Attractions | Stirling | 1994 |
| Association of Security Consultants Limited | Bexley | 1991 |
| Association of Serbian Chetniks Ravne Gore in Great Britain Limited | | 1961 |
| Association of Service Drop-In Centres Ltd | Crowborough | 2020 |
| Association of Serviced Apartment Providers | Highnam | 2009 |
| Association of Sign Language Interpreters | Chester | 2003 |
| Association of Solicitor Notaries in Greater London | Croydon | 1985 |
| Association of Somali Women and Children (Aswac) | Battersea, London | 2005 |
| Association of Somatic and Integrative Sexologists Ltd | Norwich | 2013 |
| Association of Spanish Nurses and Healthcare Workers Isabel Zendal | St. Albans | 2025 |
| Association of Specialist Underpinning Contractors | Huntingdon | 1992 |
| Association of Studio & Production Equipment Companies Ltd | Burgess Hill | 1994 |
| Association of Subcontractors Ltd | Mexborough | 2021 |
| Association of Super Recognisers Limited | Orpington | 2017 |
| Association of Surgeons of Great Britain and Ireland Limited | London | 2009 |
| Association of Surveyors and Architectural Consultants Ltd | London | 2014 |
| Association of Surveyors and Valuers Ltd | Southport | 2024 |
| Association of Taxation Practitioners | Leicester | 2016 |
| Association of Telugu Christians UK & Europe Ltd | Chelmsford | 2023 |
| Association of Tour Managers (UK) Limited(The) | Ramsgate | 1975 |
| Association of Tourism in Higher Education Limited | Derby | 1994 |
| Association of Tourist Attractions in Kent Limited | Canterbury | 1991 |
| Association of Town Centre Management | Swanley | 1993 |
| Association of Translation Companies Limited | White Colne | 1976 |
| Association of UK Accountants CIC | Bournemouth | 2014 |
| Association of UK Payment and Fintech Companies | London | 2020 |
| Association of Vehicle Adaptation Manufacturers Limited | Stockport | 2021 |
| Association of Vehicle Installers Ltd | Bewdley | 2020 |
| Association of Vehicle Recovery Operators Limited | London | 1977 |
| Association of Volunteer Managers Limited | Rochdale | 2007 |
| Association of Welding Distribution Limited | Dudley | 2010 |
| Association of Women Art Dealers Ltd | London | 2012 |
| Association of Women in the Arts | Upminster | 2017 |
| Associazione DI Volontariato Mondoitaliano Limited | London | 2025 |
| Assock Limited | Sittingbourne | 2019 |
| Assort Limited | London | 2024 |
| Assumption Limited | Walsall | 2022 |
| Assura Financial Ltd | London | 2017 |
| Assura Management Services Limited | Altrincham | 2007 |
| Assurant Co. (PG UK), Ltd | Crewe | 2020 |
| Assure Aesthetics Ltd | Newcastle Upon Tyne | 2022 |
| Assure Compliance Management Limited | Copmanthorpe | 2019 |
| Assure Consulting EOT Limited | Milton Keynes | 2023 |
| Assure Finance Ltd | Bury St. Edmunds | 2025 |
| Assure IT Limited | Larkhall | 2014 |
| Assure Protections Ltd | Hove | 2020 |
| Assure Tyres Limited | Chiswick | 2024 |
| Assured & Legal Wills Trusts and Estate Planning Ltd | Exmouth | 2013 |
| Assured (UK) Limited | Fareham | 2007 |
| Assured Aesthetics Ltd | Sutton-In-Ashfield | 2022 |
| Assured Autoclave Services Ltd | Rotherham | 2005 |
| Assured Aviation Services Limited | Warwick | 2015 |
| Assured Biosolids Limited | Huntingdon | 2015 |
| Assured Care Cover Ltd | Barnsley | 2019 |
| Assured Care Southport Limited | Sutton Coldfield | 2016 |
| Assured Cleaning Group Limited | Hornchurch ,Essex | 2019 |
| Assured Decontamination Services Limited | Rotherham | 2026 |
| Assured Design Services Limited | Beaminster | 2005 |
| Assured Environmental Services Limited | Skipton | 2004 |
| Assured Fire Protection & Safety Ltd | Glasgow | 2016 |
| Assured Fire Safety Limited | Chelmsford | 2005 |
| Assured Hair and Beauty Ltd | London | 2021 |
| Assured Health & Safety Services Ltd | Dunbartonshire | 2016 |
| Assured Human Resources Limited | Warwick | 2001 |
| Assured Laundry Services Ltd | Bury | 2025 |
| Assured Legacies Ltd | South Norwood | 2001 |
| Assured Micro Ltd | Glasgow | 2009 |
| Assured Operations Limited | London | 2015 |
| Assured Plans Ltd | London | 2018 |
| Assured Properties Developments Limited | London | 2017 |
| Assured Quality Management Systems Ltd | Warrington | 2022 |
| Assured Response Ltd | Poole | 2023 |
| Assured Services Cooperation Limited | London | 2022 |