| Alberello Limited | Hospitality | 2016 |
| Albion RA Ltd | Other services | 2016 |
| Alchemist VENTURES14 Ltd | Wholesale & retail | 2026 |
| Alder Consulting (UK) Ltd | Professional & scientific | 2002 |
| Aldor Group Limited | Construction | 2024 |
| Alectrans Ltd | Transport & logistics | 2018 |
| Aleena Private Limited | Transport & logistics | 2019 |
| Aleks Taxi Ltd | Transport & logistics | 2023 |
| Alex Ayub Mattu Ltd | Wholesale & retail | 2021 |
| Alex Henry Ltd | Professional & scientific | 2026 |
| Alex Olaniyi Oyedele Limited | Information & communication | 2018 |
| Alex Repair Auto Ltd | Manufacturing | 2016 |
| Alex the Builder Ltd | Construction | 2014 |
| Alex.G Ltd | Wholesale & retail | 2014 |
| Alexander Global Solutions Ltd | Health & social care | 2024 |
| Alexander Tiling Ltd | Construction | 2024 |
| Alexandra UK Services Limited | Construction | 2017 |
| Alexiasara Limited | Construction | 2022 |
| Alexis and Family Ltd | Health & social care | 2017 |
| Alexnikfab Ltd | Construction | 2020 |
| Alfa Comm Limited | Manufacturing | 2021 |
| Alfa Ventures Limited | Construction | 2026 |
| ALI 786 Produce Ltd | Wholesale & retail | 2015 |
| ALI Catering Equipment Ltd | Wholesale & retail | 2025 |
| Ali's Academy Limited | Health & social care | 2017 |
| Ali's Online Services Ltd | Education | 2020 |
| Alice Renewable Energy & Heating Solutions Ltd | Construction | 2026 |
| Alifa Investment Ltd | Real estate | 2022 |
| Alim Laundry Service Ltd | Other services | 2020 |
| Alis Painting & Decorating Ltd | Construction | 2025 |
| Alitata Ltd | Transport & logistics | 2018 |
| Alitech.Local Ltd | Information & communication | 2020 |
| Aliza Kitchen Cafe Limited | Hospitality | 2014 |
| ALL 4X4 Parts Ltd | Wholesale & retail | 2024 |
| ALL Hydroponics Ltd | Agriculture & fishing | 2019 |
| ALL in One Box Ltd | Construction | 2022 |
| ALL Islands Caribbean Ltd | Hospitality | 2025 |
| ALL Round Caregivers Limited | Health & social care | 2020 |
| ALL Saints Properties Management Ltd | Real estate | 2019 |
| ALL Stripout Ltd | Construction | 2025 |
| ALL Women's Network Ltd | Other services | 2017 |
| Allianz Secure Ltd | Professional & scientific | 2022 |
| Allied Consultancy & Facilities Management Ltd | Wholesale & retail | 2025 |
| Allied Energy Solutions Ltd | Construction | 2025 |
| Allied Management Support Ltd | Professional & scientific | 2025 |
| Allied Secure Ltd | Construction | 2018 |
| Allurian Mart Ltd | Wholesale & retail | 2026 |
| Alluxezo Ltd | Wholesale & retail | 2025 |
| Allyxpress Ltd | Professional & scientific | 2020 |
| Almef Ltd | Information & communication | 2018 |
| Almeida Build Group Ltd | Construction | 2026 |
| Almoruf Investments Limited | Wholesale & retail | 2019 |
| Alnamir Ltd | Administrative & support | 2019 |
| Alpha 4 U Services Ltd | Professional & scientific | 2019 |
| Alpha BSE Training Ltd | Education | 2017 |
| Alpha Force Security Services Ltd | Administrative & support | 2017 |
| Alpha Fragrances Ltd | Wholesale & retail | 2025 |
| Alpha Group 1 Ltd | Wholesale & retail | 2025 |
| Alpha Movers UK Limited | Transport & logistics | 2023 |
| Alpha Romero Ltd | Financial services | 2025 |
| Alpha Security Solutions Ltd | Administrative & support | 2010 |
| Alpha Telecommunications Limited | Information & communication | 2009 |
| Alpha Triple Ace Limited | Construction | 2025 |
| Alpha Tuition Centre Ltd | Education | 2024 |
| Alpha Welfare Solutions Ltd | Real estate | 2012 |
| Alster Textiles Limited | Wholesale & retail | 2023 |
| Althea Smith, Skincare Ltd | Health & social care | 2022 |
| Althrix Ltd | Professional & scientific | 2026 |
| Altix Lifts Limited | Manufacturing | 2025 |
| Altiyus Ltd | Construction | 2025 |
| Alukasa Ltd | Wholesale & retail | 2024 |
| Alvin Electrical Ltd | Construction | 2024 |
| ALX ONA Ltd | Construction | 2025 |
| ALZ Homes Limited | Real estate | 2024 |
| AM & JL Co Ltd | Construction | 2022 |
| AM Prime Construction Ltd | Construction | 2018 |
| AM Repair Centre Ltd | Wholesale & retail | 2023 |
| AM UK Group Limited | Information & communication | 2022 |
| AMA Specialist Recruitment & Consultancy Services Ltd | Administrative & support | 2021 |
| Amadin Limited | Health & social care | 2024 |
| Amaeva Ltd | Real estate | 2026 |
| Amanah Consultancy & Training Ltd | Professional & scientific | 2025 |
| Amani Access Service Ltd | Transport & logistics | 2026 |
| Amani Asan Ltd | Hospitality | 2019 |
| Amani Care Ltd | Health & social care | 2022 |
| Amanuel Transport Service Ltd | Transport & logistics | 2026 |
| Amar Bazar Ltd | Wholesale & retail | 2017 |
| Amari Wellness Ltd | Health & social care | 2024 |
| Amario Barking & Dagenham Motors Ltd | Manufacturing | 2026 |
| Amathus Shoes Limited | Manufacturing | 2002 |
| Amazezone Ltd | Wholesale & retail | 2020 |
| Amazing Corn Limited | Wholesale & retail | 2022 |
| Amazing Glory Services Ltd | Administrative & support | 2026 |
| Amba Forwarding (London) Limited | Transport & logistics | 1976 |
| Amba Logistic Services Limited | Transport & logistics | 2026 |
| Ambaji Properties Ltd | Real estate | 2021 |
| Ambala IT Limited | Information & communication | 2024 |
| Ambeg Ltd | Real estate | 2020 |
| Ambeg Property Investments Ltd | Real estate | 2020 |
| Amber Construction Group Ltd | Construction | 2021 |