| Alidade Advisory Ltd | Information & communication | 2026 |
| Alincourt (Roofing) Limited | Construction | 1992 |
| Alinina Consulting Ltd | Other services | 2015 |
| Alinka Media Limited | Professional & scientific | 2002 |
| Alison Robson-Young Limited | Professional & scientific | 2016 |
| ALL About Blockages Ltd | Water & waste | 2024 |
| ALL About Services Limited | Construction | 2023 |
| ALL Ace Media Ltd | Information & communication | 2025 |
| ALL Automotive Ltd | Wholesale & retail | 2018 |
| ALL Boxed Removals and Storage Limited | Transport & logistics | 2016 |
| ALL Counties Farming Ltd | Agriculture & fishing | 2021 |
| ALL Counties Hearing Limited | Health & social care | 2006 |
| ALL for One Solutions Ltd | Administrative & support | 2019 |
| ALL Roofing Works Limited | Construction | 2025 |
| ALL Round Paving and Landscaping Ltd | Professional & scientific | 2026 |
| ALL Solar Works Limited | Construction | 2018 |
| ALL West Systems Electrical Ltd | Administrative & support | 2018 |
| ALL Works Services Limited | Financial services | 2025 |
| Allbeck Developments Limited | Real estate | 2000 |
| Allbeck Investments Limited | Real estate | 2018 |
| Allbright Painting Ltd | Construction | 2019 |
| Allcomm Consultants Limited | Construction | 2010 |
| Alleyoops Skates & Board Ltd | Wholesale & retail | 2017 |
| Allotment Investments Ltd | Real estate | 2025 |
| Allow Moments Ltd | Information & communication | 2023 |
| Allplay Padel Limited | Arts & recreation | 2024 |
| Allsops C.T.F. Ltd. | Manufacturing | 1989 |
| Allstyles Upholstery Limited | Manufacturing | 2004 |
| Allure Beauty Suites Limited | Health & social care | 2024 |
| Allweather Development Holdings Limited | Construction | 2023 |
| Allweather Roofing & Construction Limited | Construction | 2012 |
| Almalumi Group Ltd | Health & social care | 2020 |
| Alme Management Ltd | Real estate | 2020 |
| ALPASTORGSK12 Limited | Hospitality | 2025 |
| Alpha Projects (Holdings) Limited | Financial services | 2018 |
| Alpha Projects (Sussex) Ltd | Real estate | 2016 |
| Alphawave IP Group Limited | Financial services | 2020 |
| Alpine Designs and Adventures Limited | Information & communication | 2006 |
| Alps F S Limited | Financial services | 1991 |
| ALR Storage and Parts Limited | Wholesale & retail | 2025 |
| Alshin Limited | Wholesale & retail | 2023 |
| Altair Acquisitions Limited | Construction | 2010 |
| Altis Industries Limited | Wholesale & retail | 1976 |
| Altitude Insurance Brokers Ltd | Financial services | 2023 |
| Altogold Limited | Hospitality | 1977 |
| Alttek Ltd | Hospitality | 2025 |
| Alun Powell Ltd | Professional & scientific | 2023 |
| Alvaplast UK Limited | Wholesale & retail | 2001 |
| Alverstone Autos Limited | Wholesale & retail | 2007 |
| Alvfrase Global Limited | Financial services | 2025 |
| Al’S Drum School Ltd | Education | 2026 |
| AM and DM Property Limited | Real estate | 2024 |
| AM Supply Ltd | Administrative & support | 2017 |
| Amanda COX Counselling Ltd | Health & social care | 2019 |
| Amanda J Events Limited | Other services | 2015 |
| Amazon Access Solutions Limited | Construction | 2020 |
| Ambientec Limited | Professional & scientific | 2018 |
| Ambio Capital Limited | Financial services | 2019 |
| Ambrook Holdings Ltd | Real estate | 2025 |
| AMC Motorhomes Ltd | Wholesale & retail | 2013 |
| Amdl Ltd | Real estate | 2024 |
| Amelia House Partners LLP | | 2006 |
| Amelia House Property Company Limited | Real estate | 2020 |
| Amena Holdings Ltd | Real estate | 2023 |
| Americanino Limited | Wholesale & retail | 1986 |
| AMF Media Ltd | Information & communication | 2006 |
| Amherst Worldwide Limited | Real estate | 2022 |
| AMI Bistro Limited | Hospitality | 2014 |
| Amicus&Co Limited | Professional & scientific | 2017 |
| Ammm Ltd | Transport & logistics | 2017 |
| Ammonyte Holdings Limited | Real estate | 2021 |
| AMO Homes Limited | Real estate | 2017 |
| Amorette Limited | Real estate | 1964 |
| Ampd Limited | Wholesale & retail | 2024 |
| Ampersand Services Ltd | Administrative & support | 2025 |
| Amra Investments Limited | Professional & scientific | 2017 |
| AMS Autos Ltd | Professional & scientific | 2026 |
| AMV Property Limited | Real estate | 2018 |
| AN MK Events Ltd | Hospitality | 2025 |
| AN Outsider Limited | Professional & scientific | 2021 |
| Ana-Bility 0-18 Ltd | Health & social care | 2022 |
| Anagram Interiors Limited | Other services | 2009 |
| Anapnoi Limited | Professional & scientific | 2023 |
| Anara Property Ltd | Real estate | 2023 |
| ANB Trans Ltd | Construction | 2017 |
| Anca Estates Limited | Real estate | 2024 |
| Anca Garage (Worthing) Limited | Wholesale & retail | 1971 |
| Anchor Digital Ltd | Information & communication | 2025 |
| Anchor Insurance Services Ltd. | Financial services | 2002 |
| Anchor Mortgages Limited | Financial services | 2004 |
| Andaaz Indian Restaurant UK Limited | Hospitality | 2025 |
| Anderson Antiques Limited | Wholesale & retail | 2013 |
| Anderson Associates (Consultancy) Limited | Extraterritorial | 2001 |
| Anderson Taverns Limited | Hospitality | 1993 |
| Andrew Allan Properties Limited | Administrative & support | 2002 |
| Andrew Appleyard Consulting Limited | Professional & scientific | 2018 |
| Andrew KAY Records Limited | Wholesale & retail | 2003 |
| Andrew Simpson Planning Limited | Professional & scientific | 2019 |
| Andrew Stewart Services Limited | Construction | 2003 |
| Andy Birch Bricklaying Services Ltd | Construction | 2014 |