| Aingarth Rest Home Limited | Colwyn Bay | 2013 |
| Ainon Health Ltd | Dartford | 2022 |
| Ainsley Clinic Limited | St. Asaph | 2014 |
| Ainslie Baker Consulting Limited | London | 2016 |
| Ainsty Dental Practice Limited | Ellesmere Port | 2013 |
| Ainsworth Oncology Limited | Bury St. Edmunds | 2026 |
| Ainsworth Psychology Service Ltd | Ryde | 2016 |
| Ainsworth Village Dental Practice Limited | Salisbury | 2013 |
| Aintree Day Nursery & Kids Club Ltd | Liverpool | 2014 |
| Aintree Kidz Limited | Liverpool | 2022 |
| Aintree Services Ltd | York | 2021 |
| AIO Events CIC | London | 2023 |
| Aioanei Ltd | Manchester | 2014 |
| Aion Clinic Ltd | London | 2024 |
| Aion Health Care & Support Services Limited | Chelmsford | 2025 |
| Aion Health Care Ltd | Newcastle Upon Tyne | 2024 |
| Aion Labs Medical Group Ltd | London | 2025 |
| Aione Health Limited | Ilford | 2025 |
| AIP Care Ltd | Blackburn | 2023 |
| AIP Dynamics C.I.C. | London | 2020 |
| AIP Healthcare Ltd | Harrow | 2023 |
| AIP8 Ltd | Blackburn | 2025 |
| Aiphysio Ltd | Manchester | 2023 |
| Air Aesthetics Birmingham Ltd | Bromsgrove | 2016 |
| Air Ambulance Charity Kent Surrey Sussex | Chatham | 1993 |
| Air Ambulance Medical Services (Heathrow) Ltd | London | 2024 |
| Air Anaesthesia Limited | Lytham St. Annes | 2006 |
| Air Arena Chichester Limited | Leigh-On-Sea | 2017 |
| Air Consultants Ltd | London | 2014 |
| Air Land & Sea Repatriation Services Ltd | Horsham | 2022 |
| Air Liquide Healthcare Limited | Droitwich | 1988 |
| Air Medic U.K. Ltd | Banbury | 2020 |
| Air of Awakening Ltd | Birmingham | 2025 |
| Air School of Breathwork Limited | Norton St Philip | 2023 |
| Air Time for Mental Health and Wellbeing CIC | Steyning | 2024 |
| Air-Log International Ltd | London | 2023 |
| Aira Associates Ltd | London | 2025 |
| Aira Care and Support Services Limited | Milton Keynes | 2025 |
| Aira Healthcare Limited | Ipswich | 2025 |
| Aira Imaging Ltd | London | 2025 |
| Aira Psychology Limited | Tunbridge Wells | 2017 |
| Airah Care Limited | London | 2022 |
| Airam 280 Limited | High Wycombe | 2025 |
| Airam SKM Limited | Crawley | 2024 |
| Airborne Allergy Action C.I.C. | London | 2018 |
| Aircareuk Ltd | London | 2025 |
| Aircheck Services Compliance Ltd | Biggleswade | 2023 |
| Aircheck Services Limited | Mexborough | 2004 |
| Airclinical Limited | London | 2023 |
| Airdrie Clinic Ltd | Hamilton | 2019 |
| Airdrie Wellbeing Hub Ltd | Airdrie | 2024 |
| Aire Valley Psychology East Morton Limited | East Morton | 2020 |
| Airea-Artificial Intelligence Research & Ethics Alliance (I4U) Limited | London | 2023 |
| Aireborough Voluntary Services to the Elderly (Avsed) | Leeds | 2015 |
| Airedale Homes Project | Keighley | 1991 |
| Airedale Locums Ltd | Leeds | 2025 |
| Airedale NO1 Ltd | Barnet | 2021 |
| Airedale Physiotherapy Clinic Limited | Keighley | 2009 |
| Airedale Psychology & Mindfulness Ltd | Baildon | 2025 |
| Airedale Voluntary Drug and Alcohol Agency Limited | West Yorkshire | 1997 |
| Airevalley Medical Ltd | Huddersfield | 2022 |
| Airhis Healthcare Ltd | Canterbury | 2024 |
| Airiemiokhale Medical Services Ltd | Harlow | 2026 |
| Airing IT OUT Limited | Blandford Forum | 2024 |
| Airmaxbranning Limited | London | 2024 |
| Airmed Bioenergy Therapy Ltd | Beauly | 2025 |
| Airmed Private GP Ltd | Leeds | 2025 |
| Airmedic International Limited | Scarborough | 2023 |
| Airmeith Ltd | Preston | 2024 |
| Airmid Medical Consultancy Limited | Brighton | 2025 |
| Airmidpg Limited | Reading | 2025 |
| Airmyn Residential Ltd | Airmyn | 2018 |
| Airsec Medical Services Limited | Wrexham | 2026 |
| Airsolo Solutions Limited | Bournemouth | 2025 |
| Airthrey Care Limited | Inverness | 1988 |
| Airthrie Homes Group Ltd | Goodmayes | 2018 |
| Airview Health Limited | Sheringham | 2026 |
| Airway Anaesthesia Services Ltd | Solihull | 2022 |
| Airyn Ltd | London | 2025 |
| AIS Health Ltd | London | 2015 |
| AIS Medical & Dental Ltd | St. Helens | 2021 |
| AIS2CARE Limited | Manchester | 2018 |
| Aisa Medical Ltd | Barnet | 2009 |
| Aisah's Spa Limited | London | 2019 |
| Aisata Medical Consultancy Ltd | Leicester | 2011 |
| Aise.B Limited | London | 2022 |
| Aish Optical Ltd | London | 2022 |
| Aisha & Babirye Ltd | Reading | 2025 |
| Aisha Asmat Ltd | Morden | 2023 |
| Aisha Healthcare Limited | Ilford | 2005 |
| Aisha Healthcare Services Ltd | Coleraine | 2023 |
| Aisha Kany Ltd | Leeds | 2016 |
| Aisha Medical Ltd | Clitheroe | 2026 |
| Aisha Opthalmics Ltd | Blackburn | 2018 |
| Aisha Waraich Ltd | Leicester | 2025 |
| Aisha Welfare Trust | Liverpool | 2007 |
| Aishah Help | London | 2019 |
| Aishah OPT Ltd | Leicester | 2021 |
| Aishakivumbi Limited | London | 2024 |
| Aishwaran Ltd | Solihull | 2016 |