| Airways Pension Scheme Trustee Limited | Harmondsworth | 2016 |
| Airweb Urbanthings Limited | Hull | 2022 |
| Airzyboy Industries Ltd | London | 2025 |
| AIS Global Ventures Limited | Sutton | 2025 |
| AIS Group Companies Limited | London | 2013 |
| AIS Mechanical Limited | Newmarket | 2026 |
| AIS Solutions Investment Ltd | London | 2024 |
| Aisa Financial Planning Limited | Devizes | 1998 |
| Aisa Financing Ltd. | London | 2026 |
| Aisha & Kaveet Holding Ltd | Surbiton | 2025 |
| Aishad Property Finance Ltd | Luton | 2020 |
| Aishel Limited | London | 2022 |
| Aisholt Consultancy Limited | Taunton | 2001 |
| Aisl Holdings Limited | Harlow | 2025 |
| Aisling Sheedy Ltd | Doncaster | 2022 |
| Aism Holdings Limited | King'S Lynn | 2024 |
| Aismare Limited | London | 2011 |
| AIT Holdings Ltd | London | 2023 |
| AIT UK Acquisition Company Limited | Newcastle Upon Tyne | 2018 |
| Aitch Group Holdings Ltd | London | 2022 |
| Aitchesse Limited | London | 2015 |
| Aitchison Holding Company Ltd | Warrington | 2023 |
| Aitchson Holdings Limited | Newcastle Upon Tyne | 2026 |
| Aite-Novarica UK Holdings Limited | East Twickenham | 2022 |
| Aiti Holdings Limited | London | 2000 |
| Aitken & Aitken Holdings Ltd | Isle Of South Uist | 2018 |
| Aitken Advisory Limited | Winchester | 2023 |
| Aitken Alexander Holdings Limited | London | 2024 |
| Aitken Financial Services Ltd | Grangemouth | 2021 |
| Aitken Strategies Limited | Chippenham | 2025 |
| Aitken Venture Group Ltd | Brough | 2025 |
| Aitkens Group Limited | Glasgow | 2020 |
| Aitma Limited | Northampton | 2018 |
| Aitopx Global Limited | Kington | 2025 |
| Aitus Group Holdings Limited | Ely | 2018 |
| Aitw Limited | Newark | 2022 |
| AIU Global Investments Ltd | Bristol | 2025 |
| AIU Group Ltd | Bolton | 2024 |
| AIU Holdings Ltd | Bristol | 2022 |
| Aiuk Capital Limited | London | 2025 |
| Aiuk Group Limited | London | 2025 |
| Aiuk Holdings Ltd | Middlesbrough | 2021 |
| Aiuk Services Limited | London | 2012 |
| Aiur Ltd | London | 2021 |
| AIV Capital Limited | London | 2021 |
| Aiva Group Ltd | London | 2026 |
| Aiva Holdings Limited | Wantage | 2023 |
| Aivean Research Limited | London | 2025 |
| Aives Forward Limited | Milton Keynes | 2014 |
| Aivesta Ltd | Liverpool | 2024 |
| Aivhy Holding Ltd | London | 2021 |
| AIW Mortgages Ltd | Broxburn | 2020 |
| AIX Capital Group Ltd | London | 2025 |
| Aiye Growth Ventures Ltd | London | 2026 |
| Aiyeola Holdings Limited | London | 2022 |
| Aiyou Ltd | Northolt | 2025 |
| Aizah Services Limited | Northolt | 2025 |
| Aizza Holdings Ltd | Leicester | 2026 |
| AJ & FE Priestley (Holdings) Limited | Lincoln | 2025 |
| AJ & GA Holdings Co Ltd | Stoke-On-Trent | 2025 |
| AJ & JK Shackell Ltd | Bath | 2025 |
| AJ & L Holdings Limited | Woore | 2017 |
| AJ Actuarial Services Ltd | Wembley | 2016 |
| AJ Africa Group Ltd | London | 2026 |
| AJ Anglezarke Ltd | Chorley | 2025 |
| AJ Aveley Ltd | Bexley | 2020 |
| AJ Bell Asset Management Limited | Salford Quays | 2015 |
| AJ Bell Business Solutions Limited | Salford Quays | 1995 |
| AJ Bell Digital Savings Limited | Salford Quays | 2018 |
| AJ Bell Management Limited | Salford Quays | 2000 |
| AJ Bell Securities Limited | Salford Quays | 1992 |
| AJ Bell Touch Limited | Manchester | 2020 |
| AJ Brokers Limited | London | 2013 |
| AJ Bryant Holdings Ltd | London | 2025 |
| AJ Buckley Consulting Limited | Bury St. Edmunds | 2014 |
| AJ Buckley Holdings Ltd | Winsford | 2024 |
| AJ Capital & Investments (UK) Ltd | Manchester | 2021 |
| AJ Capital Group Limited | London | 2025 |
| AJ Capital Holding Ltd | London | 2017 |
| AJ Capital Ventures Limited | Brentford | 2023 |
| AJ Clifford Ltd | Bedford | 2021 |
| AJ Creations Limited | Wembley | 2025 |
| AJ Cruz Buck Limited | Dereham | 2023 |
| AJ Elvo Group Ltd | Perivale | 2026 |
| AJ Equity Partners Ltd | Cardiff | 2025 |
| AJ Estates Holdings Ltd | Harrow | 2025 |
| AJ Finance & Logistics Ltd | Cardiff | 2019 |
| AJ Financial Services Ltd | Newbury Park | 2018 |
| AJ Global Distribution Limited | Milford Haven | 2024 |
| AJ Granby Holdings Ltd | Bootle | 2025 |
| AJ Group Holdings Limited | London | 2020 |
| AJ Group of Companies Ltd | London | 2018 |
| AJ Group Services Ltd | Epsom | 2025 |
| AJ Harding Limited | Downend | 2019 |
| AJ Hillcourt Limited | London | 2021 |
| AJ Holdings (Yorkshire) Limited | Sherburn In Elmet | 2026 |
| AJ Holdings Bath Limited | Bath | 2021 |
| AJ Holdings Fife Limited | Dundee | 2026 |
| AJ Holdings South West Limited | Saltash | 2021 |
| AJ Home Solutions Ltd | Pinner | 2017 |