| AGE Concern Chesterfield and District | Health & social care | 2011 |
| Ageek MSP PCB Ltd | Manufacturing | 2021 |
| Ageek PCB Techserv Ltd | Manufacturing | 2017 |
| Agency Sales Pro Ltd | Information & communication | 2010 |
| Aggressive Cuddles Limited | Wholesale & retail | 2023 |
| Agile in Digital Ltd | Information & communication | 2022 |
| Agnes & Cat Ltd | Wholesale & retail | 2017 |
| Agni Entertainment Ltd | Information & communication | 2025 |
| Agrecruit Limited | Administrative & support | 2019 |
| Agri Business Assistance Limited | Agriculture & fishing | 2012 |
| Agrivite Ltd | Manufacturing | 2023 |
| AI & ICT Global Solutions Ltd | Information & communication | 2024 |
| AI1 Building Services Ltd | Construction | 2024 |
| Aidilion Limited | Information & communication | 2025 |
| AIG Securities Limited | Financial services | 2021 |
| Aileron Digital Works Ltd | Information & communication | 2023 |
| Aileron Discovery Network Ltd | Information & communication | 2025 |
| Aims Holdings Limited | Financial services | 2023 |
| Aims Moor Food Ltd | Hospitality | 2015 |
| Aims Property Development Limited | Real estate | 2013 |
| Aims Surveys Limited | Professional & scientific | 2023 |
| Aindustrial Ltd | Professional & scientific | 2020 |
| Air Conditioning Services (GB) Limited | Construction | 2005 |
| Air-Change Ventilation Limited | Construction | 2001 |
| Airfire Control Limited | Construction | 2006 |
| Airfire Limited | Construction | 2021 |
| Airside Asset Management Limited | Administrative & support | 2015 |
| Airwaves-Pfp Ltd | Public administration | 2020 |
| Airwheel UK Ltd | Wholesale & retail | 2024 |
| AJ Driver Solutions Ltd | Administrative & support | 2015 |
| Aj's Hair and Studio Limited | Other services | 2020 |
| AJB Chesterfield Limited | Wholesale & retail | 2024 |
| Ajbp Holdings Limited | Financial services | 2025 |
| AJC Engineering Services Limited | Professional & scientific | 2019 |
| Ajeleko Ltd | Administrative & support | 2024 |
| AJM Care Group Ltd | Health & social care | 2025 |
| AJS Motors Limited | Wholesale & retail | 2010 |
| AJS Scaffolding Ltd | Administrative & support | 2016 |
| AJY Management Limited | Professional & scientific | 2010 |
| Aj`S Limited | Water & waste | 2010 |
| AKB Financial Services Limited | Financial services | 2019 |
| Akcs Healthcare Ltd | Health & social care | 2026 |
| Akhi's Kitchen Limited | Hospitality | 2025 |
| Akhter and Co Developments Limited | Real estate | 2024 |
| Aklxmultimedia Ltd | Professional & scientific | 2022 |
| AKO Chesters Ltd | Hospitality | 2020 |
| AKO Vale Ltd | Real estate | 2019 |
| Aksa Pizza Ltd | Hospitality | 2026 |
| Akvo Limited | Professional & scientific | 2013 |
| AL Clearance Limited | Wholesale & retail | 2025 |
| AL Waffa Limited | Hospitality | 2023 |
| Alafaq Ltd | Wholesale & retail | 2025 |
| Alan Chapman Company Ltd | Construction | 2002 |
| Alan Maris Windows Limited | Construction | 2008 |
| Alaw Consulting Ltd | Real estate | 2021 |
| Alaw Holdings Ltd | Financial services | 2019 |
| Albert Inn Limited | Hospitality | 2023 |
| Albion Dental Laboratories Ltd | Manufacturing | 2012 |
| Albtec Ltd | Professional & scientific | 2018 |
| Alder Estates Ltd | Real estate | 2024 |
| Aleksandria Sciences Limited | Professional & scientific | 2011 |
| Aleshins Ltd | Wholesale & retail | 2024 |
| Alex Cooper Photo Ltd | Professional & scientific | 2023 |
| Alexa Meale Ltd | Extraterritorial | 2012 |
| Alexandra Dental Care Ltd | Health & social care | 2013 |
| Alexandra Health Care Limited | Health & social care | 1994 |
| Alexandra Property Investors Ltd | Hospitality | 2023 |
| Alexandra Solutions Limited | Transport & logistics | 2010 |
| Alexemis Ltd | Transport & logistics | 2025 |
| ALF Sameday Limited | Transport & logistics | 2026 |
| ALF Vini Limited | Wholesale & retail | 2010 |
| Alfa Hydraulics Limited | Manufacturing | 2015 |
| Algarve - Golf (U.K.) Limited | Arts & recreation | 1994 |
| Alice at the Ranmoor Ltd | Hospitality | 2026 |
| Alison Hardy Limited | Financial services | 2019 |
| Aljacks DES Limited | Administrative & support | 2007 |
| Alkota Group Limited | Administrative & support | 2021 |
| ALL Bits Home Limited | Wholesale & retail | 2012 |
| ALL North Group Limited | Real estate | 2026 |
| ALL Pumps Europe Limited | Professional & scientific | 2013 |
| ALL Seasons Roofing Services Ltd | Construction | 2020 |
| ALL Waste Matters Limited | Administrative & support | 2006 |
| Allan Investments Limited | Administrative & support | 2020 |
| Allard Care Ltd | Health & social care | 2015 |
| Allen & Orr,Limited | Manufacturing | 1909 |
| Allen Jackson Bakery Limited | Manufacturing | 2023 |
| Alleppey Kitchen Ltd | Hospitality | 2023 |
| Alliance Electronics Limited | Manufacturing | 1993 |
| Alliance K9 Supplies Ltd | Wholesale & retail | 2022 |
| Allround Accountancy Services Limited | Professional & scientific | 2012 |
| Alma Care Homes Broome Limited | Health & social care | 2018 |
| Alma Care Homes Broome Property Limited | Health & social care | 2018 |
| Alma Care Homes Holywell Limited | Health & social care | 2017 |
| Alma Contract Supplies Limited | Wholesale & retail | 1998 |
| Alma Nursing Services Ltd | Health & social care | 2024 |
| Alma Rail Limited | Professional & scientific | 2002 |
| Almost Everything Limited | Financial services | 2022 |
| ALP Business Support Services Ltd | Financial services | 2018 |
| ALP Design Limited | Professional & scientific | 2024 |
| Alpha FM Services Ltd | Water & waste | 2006 |