| ALL Cisterns Go Plumbing and Bathroom Installations Limited | Extraterritorial | 2006 |
| ALL Dental Limited | Health & social care | 2024 |
| ALL Divine Grace Limited | Wholesale & retail | 2022 |
| ALL EAT App Network Technology Incorporated Ltd | Wholesale & retail | 2017 |
| ALL Hers Ltd | Other services | 2025 |
| ALL in 1 Autos Ltd | Wholesale & retail | 2025 |
| ALL in One Eyecare Limited | Wholesale & retail | 2008 |
| ALL Inclusive Advice and Training Ltd | Education | 2009 |
| ALL Kinds of Houses Limited | Real estate | 2025 |
| ALL Locked UP Limited | Administrative & support | 2026 |
| ALL Locked UP Safe (UK) Ltd | Other services | 2011 |
| ALL New Stuff Limited | Wholesale & retail | 2024 |
| ALL Plant Movements Limited | Wholesale & retail | 2013 |
| ALL Saints (Eastbourne) Management Company Limited | Households | 2007 |
| ALL Seasons Enterprise Ltd | Other services | 2013 |
| ALL Seasons Plumbing and Heating Limited | Construction | 2019 |
| ALL the Best Driving School Limited | Education | 2025 |
| ALL Well-Being Limited | Information & communication | 2023 |
| All's Plumbing Ltd | Construction | 2015 |
| ALL4ONESERVICES Ltd | Health & social care | 2022 |
| Allain Creatives Ltd | Administrative & support | 2021 |
| Allayura Limited | Wholesale & retail | 2025 |
| Allcare Workforce Ltd | Administrative & support | 2023 |
| Allegna | Education | 2011 |
| Allegna Partnership | Administrative & support | 2012 |
| Allen Heritage Ltd | Real estate | 2002 |
| Allenmead Management Company Limited | Real estate | 1974 |
| Allens Homes Ltd | Real estate | 2024 |
| Allensway Limited | Information & communication | 2003 |
| Alleyand Co UK Ltd | Construction | 2019 |
| Alli, Olateju & Daughters Ltd | Real estate | 2022 |
| Alliance Care Professionals Ltd | Administrative & support | 2019 |
| Alligator Logistics Ltd | Transport & logistics | 2025 |
| Allinclusive Properties Ltd | Real estate | 2025 |
| Allingtons Residents Company Limited | Households | 2006 |
| Allosbrand Ltd | Wholesale & retail | 2025 |
| Allretail Ltd | Wholesale & retail | 2026 |
| Allrounders Fitness Limited | Wholesale & retail | 2020 |
| Allsop Place Management Limited | Households | 2010 |
| Allsouls International Ltd | Health & social care | 2018 |
| Alltech Maintenance Services Ltd. | Construction | 2014 |
| Allyoucanbuy Ltd | Wholesale & retail | 2020 |
| Alma Care (UK) Limited | Health & social care | 2011 |
| Alma Road Management Company Limited | Households | 1983 |
| Almax Innovations Ltd | Wholesale & retail | 2018 |
| Almeida Fittings Ltd | Other services | 2025 |
| ALN Consultancy Ltd | Information & communication | 2018 |
| Alnaser UK Export Ltd | Wholesale & retail | 2021 |
| Aloe Vera Centre Limited | Wholesale & retail | 1995 |
| Alonso Builder Ltd | Construction | 2005 |
| Alonso CAP Ltd | Other services | 2025 |
| Aloura Ltd | Real estate | 2025 |
| ALP London Limited | Other services | 2018 |
| Alp-Carve Ltd | Administrative & support | 2017 |
| Alpa BUS & Coach Travel Limited | Transport & logistics | 2003 |
| Alpal 1 Ltd | Real estate | 2025 |
| Alpal Developments Limited | Construction | 2003 |
| Alpas Sports UK Limited | Wholesale & retail | 2014 |
| Alpcon Homes Limited | Construction | 2015 |
| Alpha 3 Ltd | Wholesale & retail | 2019 |
| Alpha CP Services Limited | Administrative & support | 2017 |
| Alpha Elite Group Limited | Professional & scientific | 2017 |
| Alpha Estates (Crofton Park) Limited | Real estate | 2020 |
| Alpha Estates (Petts Wood) Limited | Real estate | 2021 |
| Alpha Glaze (Croydon) Limited | Construction | 2000 |
| Alpha Heating Services Ltd | Construction | 2018 |
| Alpha House Freehold Management Company Ltd | Households | 2021 |
| Alpha Protection Limited | Administrative & support | 2018 |
| Alpha Removals Ltd | Transport & logistics | 2023 |
| Alpha Shipping Line Ltd | Transport & logistics | 2023 |
| Alpha Site Services Limited | Construction | 2022 |
| Alpha W1 Ltd | Wholesale & retail | 2018 |
| ALPHA2OMEGA Consulting Ltd | Professional & scientific | 2024 |
| Alphachain Capital Ltd | Information & communication | 2017 |
| Alphacog Innovations Ltd | Wholesale & retail | 2024 |
| Alphaglaze Surrey Limited | Construction | 2023 |
| Alphaneon IT Media Limited | Information & communication | 2023 |
| Alphaneon Studioz Ltd | Information & communication | 2024 |
| Alphapackuk Ltd | Agriculture & fishing | 2023 |
| Alpine Court (Withington) Management Company Limited | Households | 1992 |
| Alric House Management Limited | Real estate | 2021 |
| Alsal UK Limited | Hospitality | 2025 |
| Alstart Ltd | Wholesale & retail | 2019 |
| Alta Hill Properties Limited | Households | 2024 |
| Altamaj Ltd | Wholesale & retail | 2025 |
| Alteco Consulting Ltd | Professional & scientific | 2012 |
| Alternativa Ltd | Financial services | 2014 |
| Alternative Fuel Co Ltd | Wholesale & retail | 2007 |
| Alternative Investment Solutions (Management) Limited | Financial services | 2009 |
| Althie J Ltd | Professional & scientific | 2016 |
| Althie Lifestyle Limited | Wholesale & retail | 2021 |
| Altogether Different Ltd | Professional & scientific | 2016 |
| Altogether Ginger Ltd | Manufacturing | 2022 |
| Alton Gardens Residents Association Limited | Households | 1965 |
| Altonrose Limited | Real estate | 2000 |
| Altostuart Ltd | Wholesale & retail | 2018 |
| Altruista Care UK Limited | Administrative & support | 2018 |
| Alum Grange Development Limited | Real estate | 2017 |
| Aluma Humanitarian Solutions Ltd | Professional & scientific | 2025 |
| Aluminur Ltd. | Construction | 2024 |