| Aleron Developments Limited | Real estate | 2018 |
| Aleron Fire Protection Limited | Construction | 2015 |
| Aleron Holdings Limited | Financial services | 2019 |
| Aleron House Limited | Real estate | 2021 |
| Alesiozeus Limited | Transport & logistics | 2021 |
| Alessi Building Limited | Construction | 2016 |
| Alessi Holdings Limited | Financial services | 2025 |
| Alessi Residential Limited | Real estate | 2023 |
| Alessia Trade Ltd | Administrative & support | 2019 |
| Alex Buildforce Ltd | Construction | 2026 |
| Alex Ceban Ltd | Transport & logistics | 2018 |
| Alex Creasy Ltd | Administrative & support | 2004 |
| Alex Plumbing & Heating Ltd | Construction | 2023 |
| ALEX2017 Ltd | Transport & logistics | 2021 |
| Alexander Aesthetics Ltd | Wholesale & retail | 2025 |
| Alexander and James Limited | Wholesale & retail | 2013 |
| Alexander Bradshaw Ltd | Construction | 2021 |
| Alexander Bradwell Ltd | Wholesale & retail | 2018 |
| Alexander James (Contract Interiors) Limited | Professional & scientific | 2003 |
| Alexander James Ventures Limited | Real estate | 2016 |
| Alexander Lawrence Estate Agents Ltd | Real estate | 2017 |
| Alexander Owen Consultants Limited | Health & social care | 2019 |
| Alexanders Consultants Ltd | Administrative & support | 2018 |
| Alexandra Rose Ltd | Professional & scientific | 2025 |
| Alexandru Botezat Ltd | Transport & logistics | 2017 |
| Alexandsophyatrans Limited | Transport & logistics | 2018 |
| Alexena Limited | Real estate | 1979 |
| Alexv Construction Ltd | Construction | 2026 |
| Alfa & SON Investments Ltd | Real estate | 2024 |
| Alfa International Management Limited | Wholesale & retail | 2021 |
| Alfa Plastering Ltd | Construction | 2021 |
| Alfast Fixings & Fasteners Limited | Wholesale & retail | 1980 |
| Alfred Real-Worth Limited | Administrative & support | 2015 |
| Alfred's Community Outreach | Other services | 2020 |
| ALG Active Learning Centres Limited | Arts & recreation | 2021 |
| ALG Cognita Limited | Arts & recreation | 2008 |
| ALG Consulting Ltd | Education | 2022 |
| Algar Trading Ltd | Extraterritorial | 2024 |
| Alhaadi Ltd | Health & social care | 2021 |
| ALI Family Real Estate Limited | Real estate | 2024 |
| ALI Gaxnug Limited | Transport & logistics | 2018 |
| ALI Hussain Property Investment Ltd | Real estate | 2025 |
| Alias Business Systems Ltd | Administrative & support | 2016 |
| Alichem (UK) Limited | Professional & scientific | 2006 |
| Alicia Holdings Ltd | Professional & scientific | 2026 |
| Alif Digital Limited | Information & communication | 2024 |
| Alif Digital Technology Limited | Information & communication | 2023 |
| Align Blocks Solutions Ltd | Information & communication | 2022 |
| ALIGN360 Chiropractic Ltd | Health & social care | 2025 |
| Aligning Cultures Ltd | Arts & recreation | 2025 |
| Alin Engineering Ltd | Construction | 2024 |
| Alin Trans Ltd | Transport & logistics | 2013 |
| ALIN1982 Ltd | Transport & logistics | 2023 |
| Alipapa Ltd | Health & social care | 2024 |
| Alipta Blue Limited | Professional & scientific | 2025 |
| Alistair Ashley Healthcare & Training Limited | Health & social care | 2016 |
| Alistair Williams Limited | Professional & scientific | 2012 |
| Aliuks Ltd | Transport & logistics | 2024 |
| Alix A2Z Limited | Wholesale & retail | 2025 |
| Aljbeno Ltd | Wholesale & retail | 2022 |
| Alju Ltd | Transport & logistics | 2017 |
| Alka Mishra Ltd | Health & social care | 2013 |
| Alkaline Cleaning Ltd | Administrative & support | 2023 |
| ALL About Early Years Ltd | Education | 2024 |
| ALL Accountants Ltd. | Professional & scientific | 2019 |
| ALL Aspects Cleaning Services Ltd | Administrative & support | 2026 |
| ALL Bespoke Limited | Professional & scientific | 2012 |
| ALL Care IT Limited | Information & communication | 2020 |
| ALL Cars Autos Ltd | Wholesale & retail | 2024 |
| ALL Floors (UK) Limited | Construction | 2011 |
| ALL Floors Trust Company Limited | Construction | 2022 |
| ALL Good Cafe CIC | Hospitality | 2025 |
| ALL Group MK Ltd | Construction | 2026 |
| ALL in Motion Solutions Ltd | Transport & logistics | 2025 |
| ALL in One Logistics Ltd | Transport & logistics | 2024 |
| ALL in One MK Ltd | Construction | 2025 |
| ALL Insports Limited | Information & communication | 2009 |
| ALL Khan Ltd | Information & communication | 2019 |
| ALL Maintenance Solutions Limited | Construction | 2019 |
| ALL Media Comm. Ltd | Information & communication | 2018 |
| ALL N One Wholesale Limited | Wholesale & retail | 2022 |
| ALL Nightingale Ltd | Administrative & support | 2022 |
| ALL Part-Timers Ltd. | Administrative & support | 2022 |
| ALL Play Sport CIC | Arts & recreation | 2020 |
| ALL Purpose Home Delivery Limited | Transport & logistics | 2016 |
| ALL Purpose Limited | Professional & scientific | 2018 |
| ALL Rise Athletics Limited | Other services | 2025 |
| ALL Season Roofing Limited | Construction | 2025 |
| ALL Season Treecare Ltd | Administrative & support | 2025 |
| ALL Service Games Ltd | Other services | 2026 |
| ALL Sports Whispers Limited | Information & communication | 2017 |
| ALL Star Complete Development Ltd | Hospitality | 2020 |
| ALL Stars 24/7 Healthcare Limited | Health & social care | 2023 |
| ALL Stars Badminton Limited | Arts & recreation | 2011 |
| ALL Things Hospitality Ltd | Extraterritorial | 2024 |
| ALL Trees Garden Services Ltd | Administrative & support | 2022 |
| ALL Weather Courts Limited | Administrative & support | 1995 |
| All-Season Shine Ltd | Administrative & support | 2025 |
| Alla Limited | Transport & logistics | 2018 |
| Alladin Briggs Ltd | Real estate | 2025 |