| Active CAB Ltd | Transport & logistics | 2021 |
| Acumen Mortgages Limited | Financial services | 2022 |
| Acute Gardening Services Limited | Professional & scientific | 2003 |
| Acvs a Complete Vehicle Solution Ltd | Wholesale & retail | 2023 |
| AD Chinese Centre Limited | Administrative & support | 2017 |
| AD Planning and Design Ltd | Professional & scientific | 2014 |
| AD VIP Barbers Ltd | Other services | 2025 |
| Ad-Hoque Consulting Ltd | Information & communication | 2025 |
| Adam Kick Limited | Professional & scientific | 2026 |
| Adare Tayler Consulting Limited | Professional & scientific | 2025 |
| Adare Tayler Limited | Real estate | 2010 |
| Adavirtual Business Support Limited | Administrative & support | 2020 |
| ADEPTLEAD2 Limited | Professional & scientific | 2026 |
| Ader United Ltd | Households | 2010 |
| Adgo Limited | Professional & scientific | 2025 |
| Adhams Barber Ltd | Administrative & support | 2017 |
| Aditya Labs Ltd | Information & communication | 2022 |
| ADL Care Provider Ltd | Health & social care | 2024 |
| Adniro Services Ltd | Transport & logistics | 2010 |
| Adrian Hodea Limited | Other services | 2019 |
| Adro Motors Ltd | Wholesale & retail | 2021 |
| Adrunner Ltd | Professional & scientific | 2024 |
| Adsparkpro Ltd | Information & communication | 2024 |
| Adunhorla Ltd | Wholesale & retail | 2026 |
| Advance Auto Trader Ltd | Wholesale & retail | 2025 |
| Advance Travel Solutions Ltd | Transport & logistics | 2024 |
| Advanced Oral Care Ltd | Health & social care | 2018 |
| Advanced Rent Option Ltd | Real estate | 2020 |
| Advanced Response Ltd | Health & social care | 2019 |
| Advanced Tech. Serv. UK Ltd | Construction | 2016 |
| Advancegbs Limited | Professional & scientific | 2021 |
| AEG Fuels UK Limited | Wholesale & retail | 2011 |
| Aegivis Systems Ltd | Information & communication | 2026 |
| Aeps Services Ltd | Other services | 2013 |
| Aerdata UK Limited | Information & communication | 2002 |
| Aero Mobility Cars Limited | Transport & logistics | 2020 |
| Aeroassistance Cargo Way Ltd | Information & communication | 1999 |
| Aerofix Engineering Ltd | Manufacturing | 2025 |
| Aeromobile Communications Limited | Information & communication | 2010 |
| Aerospace X Limited | Professional & scientific | 2020 |
| Aerotron Avotec Limited | Transport & logistics | 2016 |
| Aerotron Composites Limited | Manufacturing | 2019 |
| Aerotron Group (Holdings) Limited | Transport & logistics | 2005 |
| Aerotron Leasing Services Limited | Transport & logistics | 2008 |
| Aerotron Limited | Transport & logistics | 1973 |
| Aerotron Rotary Limited | Transport & logistics | 2010 |
| Aesthetic Trade Excellence Ltd | Wholesale & retail | 2019 |
| Aesthetics by Amal Ltd | Health & social care | 2022 |
| Aestheticsbysab's Limited | Other services | 2025 |
| Aestivo Ltd | Wholesale & retail | 2025 |
| Affetto Gifts Ltd | Wholesale & retail | 2026 |
| Affinity Sales Ltd | Information & communication | 2016 |
| Affordable MAN With Van Ltd | Transport & logistics | 2025 |
| Afison Services Ltd | Information & communication | 2024 |
| AFK Logistics Ltd | Transport & logistics | 2019 |
| Aframes 4 Site Ltd | Manufacturing | 2019 |
| Afresh Office Cleaning Ltd | Administrative & support | 2012 |
| Afribrits Properties Limited | Real estate | 2025 |
| African Wildlife Foundation | Professional & scientific | 2007 |
| Afrinapé Limited | Hospitality | 2017 |
| Afro Hair Religion Ltd | Other services | 2024 |
| AFS (Redhill) Limited | Wholesale & retail | 2005 |
| Aftab ALI Shah Ltd | Wholesale & retail | 2025 |
| AG Green Services Ltd | Transport & logistics | 2023 |
| Agastya Limited | Information & communication | 2014 |
| Agathi Enterprise Limited | Wholesale & retail | 2024 |
| AGD Traders Ltd | Construction | 2020 |
| Aged Steakhouse Ltd | Hospitality | 2024 |
| Agency 54 Ltd | Extraterritorial | 2009 |
| Agency Options Ltd | Real estate | 2017 |
| Agentprime Ltd | Information & communication | 2026 |
| Agile Bureau Ltd | Information & communication | 2013 |
| Agile Designs Ltd | Professional & scientific | 2023 |
| Agilogica Limited | Information & communication | 2024 |
| Agnolytics Ltd | Information & communication | 2024 |
| Agnon Associates Limited | Professional & scientific | 2024 |
| Agnon LLP | | 2017 |
| Agrassure Limited | Agriculture & fishing | 2019 |
| Agri Ventura PLC | Professional & scientific | 2008 |
| Agricglow Limited | Wholesale & retail | 2025 |
| AH Accountants and Tax Advisors Limited | Professional & scientific | 2016 |
| AH Accountax Ltd | Professional & scientific | 2011 |
| AH Squared Data Ltd | Information & communication | 2025 |
| Ahava Enterprise Ltd | Real estate | 2024 |
| Ahbt Limited | Education | 2016 |
| AHC Properties Management Ltd | Real estate | 2024 |
| Ahmedia Limited | Administrative & support | 2009 |
| Ahmedmediagroup Ltd | Information & communication | 2012 |
| Ahmestates Ltd | Real estate | 2021 |
| AHR CAD Ltd | Professional & scientific | 2017 |
| Ahsha Ltd | Wholesale & retail | 2025 |
| AI Estimate Quoting Service Ltd | Information & communication | 2026 |
| AI Genie Ltd | Information & communication | 2023 |
| AI GTM Studio Ltd | Information & communication | 2026 |
| AI London Limited | Manufacturing | 2016 |
| AIK REI Ltd | Construction | 2023 |
| Ailm Holdings Ltd | Financial services | 2025 |
| AIM Group Lettings Ltd | Real estate | 2023 |
| AIM Healthcare Services Limited | Health & social care | 2023 |
| AIM R&T Ltd | Wholesale & retail | 2019 |