| Adam Bawer Transport Ltd | Transport & logistics | 2015 |
| Adam Smith Consultants Limited | Construction | 1999 |
| Adams Property and Investments Ltd | Real estate | 2024 |
| Addfarn Limited | Administrative & support | 1992 |
| Adec Property Consultants Ltd | Professional & scientific | 2021 |
| Adex Logistics Ltd | Transport & logistics | 2015 |
| Adhi Transport Ltd | Transport & logistics | 2024 |
| ADI ROX Ltd | Construction | 2026 |
| Adithi's Aroma Kitchen Ltd | Hospitality | 2024 |
| Adnantransport Limited | Transport & logistics | 2023 |
| Adrenaline MX Ltd | Wholesale & retail | 2018 |
| Adrian Property Services Ltd | Construction | 2024 |
| ADS Property Holdings Limited | Real estate | 2024 |
| Advance Process Solutions Ltd | Manufacturing | 2025 |
| Advanced Bonding Solutions Ltd | Extraterritorial | 1988 |
| Advanced Carbon Allotropes Limited | Manufacturing | 2017 |
| Advanced Site Services Limited | Construction | 2009 |
| Adverse Weather Collective Ltd | Wholesale & retail | 2023 |
| Aenic Ltd | Administrative & support | 2025 |
| Aevans Financial Services Ltd | Financial services | 2011 |
| AF Power Ltd | Energy | 2023 |
| AFA Properties Ltd | Real estate | 2019 |
| Affiliate Services Limited | Transport & logistics | 2026 |
| Affordable Landscape and Construction Services Ltd | Construction | 2014 |
| AFL Packaging Solutions Ltd | Wholesale & retail | 2012 |
| AG Clinics (Nottingham) Ltd | Other services | 2025 |
| AG Electrical and Instrumentation Services Limited | Construction | 2015 |
| Agaran Ltd | Wholesale & retail | 2026 |
| Agardsley Investments Limited | Arts & recreation | 2011 |
| Agency-Z Limited | Transport & logistics | 1982 |
| AGH Puran Ltd | Transport & logistics | 2021 |
| AGI Drivers Ltd | Transport & logistics | 2017 |
| Agile Legal 360 Ltd | Professional & scientific | 2023 |
| Agprovox Ltd | Construction | 2025 |
| Agri-Tech West Limited | Financial services | 2016 |
| AH Online Retail Ltd | Information & communication | 2026 |
| Ahemali Ltd | Wholesale & retail | 2025 |
| Ahsh Trade Ltd | Wholesale & retail | 2026 |
| Ahva Solutions Ltd | Financial services | 2025 |
| AHW Professional Services Limited | Administrative & support | 2015 |
| AI Digital Ventures Ltd | Information & communication | 2023 |
| AIA Management Services Ltd | Professional & scientific | 2023 |
| Aiga Ltd | Professional & scientific | 2021 |
| AIM Neuromodulation Ltd | Health & social care | 2022 |
| AIM Textiles & Co Ltd | Wholesale & retail | 2025 |
| Aims Fitness Limited | Wholesale & retail | 2026 |
| Airgen UK Projects Limited | Construction | 2025 |
| Airport City Church C.I.C. | Other services | 2025 |
| AJ Agile Delivery Ltd | Information & communication | 2019 |
| AJ GAS Services Ltd | Construction | 2017 |
| AJB Logistics Limited | Transport & logistics | 2012 |
| AJC Consultants Limited | Financial services | 2005 |
| AJK Consultants Limited | Real estate | 2004 |
| AJM Automation Limited | Construction | 2000 |
| AJP Mechanical Services Ltd | Financial services | 2019 |
| AJP UK Services Limited | Construction | 2024 |
| Ajpn Limited | Real estate | 2021 |
| AJR Management Ltd | Administrative & support | 2006 |
| AJS Commercial Gardening Ltd | Administrative & support | 2020 |
| AJS Consulting (Building Envelope Advisory Service) Ltd | Professional & scientific | 2022 |
| AK Electricsx Ltd | Construction | 2025 |
| AK Process Innovations Ltd | Professional & scientific | 2026 |
| Akhand Kirtani Jatha UK Ltd | Extraterritorial | 2025 |
| AKZ Marketing Ltd | Professional & scientific | 2019 |
| AL Madina Superstore Burton Ltd | Wholesale & retail | 2020 |
| Al-Noor Fresh Food Limited | Wholesale & retail | 2024 |
| Alan MAC Feely Ltd | Arts & recreation | 2012 |
| Alan's Test Centre Limited | Wholesale & retail | 2010 |
| Alavi Optics Ltd | Health & social care | 2018 |
| Albert Driver Ltd | Transport & logistics | 2026 |
| Albion Bathrooms Limited | Wholesale & retail | 2006 |
| Albion Power Limited | Administrative & support | 2008 |
| Albion Test Centre Limited | Wholesale & retail | 2016 |
| Albm Limited | Wholesale & retail | 2021 |
| Alchemy Advance Ltd | Professional & scientific | 2011 |
| Alders Reach Limited | Real estate | 2006 |
| Aldridge Carpentry & Property Care Ltd | Manufacturing | 2018 |
| Aldt Services Ltd | Construction | 2025 |
| Aleksejsgroup Limited | Transport & logistics | 2020 |
| Alex Fire and Security Limited | Construction | 2019 |
| Alex Motors Ltd | Wholesale & retail | 2021 |
| Alex Transport Expert Ltd | Transport & logistics | 2026 |
| Alexander Accountancy (Project 1) Ltd | Professional & scientific | 2024 |
| Alexander Accountancy Limited | Professional & scientific | 2010 |
| Alexander House (South Uxbridge Street) Management Company Limited | Real estate | 2007 |
| Alexander Jean Property Group Ltd | Financial services | 2025 |
| Alexander Jean Property Holdings Ltd | Real estate | 2026 |
| Alexander Road Management Company Limited | Real estate | 2007 |
| Alexander's Business Club Limited | Construction | 2009 |
| Alexander's Financial Planning Limited | Financial services | 2019 |
| Alexandria Medics Ltd | Health & social care | 2026 |
| Alexis Management Services Limited | Health & social care | 2015 |
| Alfie's Diner Ltd | Hospitality | 2025 |
| Alfie's Ideas Ltd | Information & communication | 2020 |
| ALI Carpets Midlands Ltd | Wholesale & retail | 2025 |
| Align Body and Mind Limited | Health & social care | 2020 |
| Alinia Investments Ltd | Real estate | 2016 |
| Aljoher Ltd | Health & social care | 2025 |
| ALL About Educational Limited | Education | 2010 |
| ALL Health Group UK Limited | Administrative & support | 2025 |