| AK North East Builders Ltd | Construction | 2025 |
| AK Whitestone Ltd | Real estate | 2025 |
| AKA (Sadler Brown) Limited | Professional & scientific | 2006 |
| AKA Locums Ltd | Health & social care | 2022 |
| AKA Plumbing , Heating & Drainage North East Ltd | Construction | 2025 |
| Akaal Property Investments NE Ltd | Wholesale & retail | 2023 |
| Akawa Ltd | Professional & scientific | 2021 |
| Akay Scaffolding Limited | Construction | 2013 |
| Akbar ALI Services Limited | Wholesale & retail | 2025 |
| Akiva Videography Ltd | Arts & recreation | 2021 |
| Akkari Business Solutions Ltd | Professional & scientific | 2017 |
| AKL Floorsanding and Restoration Limited | Construction | 2019 |
| AKM Builders NE Limited | Construction | 2023 |
| AKM CS Ltd | Other services | 2022 |
| AKP Services Ltd | Hospitality | 2021 |
| Akram Invest Co Limited | Financial services | 2025 |
| Akram Locums Ltd | Health & social care | 2025 |
| AKS Inns Limited | Hospitality | 2019 |
| Aktis Gallery (UK) Limited | Administrative & support | 2009 |
| AL Bait Ltd | Hospitality | 2019 |
| AL Dhiya Ltd | Hospitality | 2025 |
| Al-Fordos Ltd | Hospitality | 2025 |
| Al-Maiyah Medical Services Limited | Health & social care | 2015 |
| Al-Naimi Limited | Wholesale & retail | 2019 |
| Alan C Cowan Ltd | Agriculture & fishing | 2022 |
| Alan Gray Limited | Wholesale & retail | 1992 |
| Albany Auto Repair Centre Limited | Wholesale & retail | 2025 |
| Albasem Homes Limited | Real estate | 2024 |
| Albatross Theatre Ltd | Arts & recreation | 2025 |
| Albert Farnell Limited | Wholesale & retail | 1944 |
| Alberts 1961 Limited | Extraterritorial | 2013 |
| Albion Holdings Group Ltd | Financial services | 2021 |
| Alchemy Business Solutions Limited | Professional & scientific | 2003 |
| Alcolizer Technology United Kingdom Limited | Professional & scientific | 2006 |
| Alcor Handling Solutions Limited | Wholesale & retail | 1990 |
| Alder Financial Limited | Financial services | 2020 |
| Alderslade Farming Limited | Agriculture & fishing | 2012 |
| Aldriyas Auto Deals Limited | Wholesale & retail | 2024 |
| Alek Construction Limited | Construction | 2022 |
| Alex Byron Hardware Ltd | Wholesale & retail | 2020 |
| Alex Martin Limited | Energy | 2025 |
| Alexander Regulatory and Quality Ltd | Professional & scientific | 2023 |
| Alexandra Peter Ltd | Hospitality | 2022 |
| Alexandra's Financial Management Group Ltd | Professional & scientific | 2018 |
| Alexandra's Financial Management Limited | Financial services | 2009 |
| Alfie Joey Limited | Arts & recreation | 2007 |
| ALG Heating Ltd | Construction | 2019 |
| Algeo Training Limited | Education | 2006 |
| Algernon Precision Engineering Limited | Manufacturing | 2001 |
| ALI Cheraghi Logistics Ltd | Transport & logistics | 2025 |
| Align Invest Limited | Wholesale & retail | 2024 |
| Alimina Ltd | Financial services | 2024 |
| Alive Safety & Rescue Limited | Wholesale & retail | 2011 |
| ALJ Property Developments Ltd | Real estate | 2026 |
| Alkou Ltd | Real estate | 2018 |
| ALL Car Parts Limited | Wholesale & retail | 2012 |
| ALL Spine Ltd | Health & social care | 2023 |
| ALL YOU SEE Underwear Limited | Manufacturing | 2022 |
| Allan Liddle (Holding) Limited | Financial services | 2014 |
| Allandale Claims Services Limited | Other services | 2019 |
| Allbrook Properties Limited | Hospitality | 2021 |
| Allegria Newcastle Ltd | Hospitality | 2019 |
| Allen & Bell Properties Ltd | Real estate | 2019 |
| Allen Valley Aromatics Limited | Wholesale & retail | 2025 |
| Allerdene Golden FRY Ltd | Hospitality | 2017 |
| Alliance Medical Solutions Limited | Real estate | 2013 |
| Alliance Podiatry Ltd | Health & social care | 2019 |
| Allscaff Services Ltd | Construction | 2019 |
| Allsolar Energy Ltd | Construction | 2026 |
| Alluxe Living Ltd | Hospitality | 2025 |
| Alluxemart Ltd | Wholesale & retail | 2025 |
| Alma Cacao Ltd | Manufacturing | 2024 |
| Alnwick Bidco Limited | Financial services | 2024 |
| Alnwick Midco Limited | Financial services | 2024 |
| Alpha Birmingham | Extraterritorial | 1963 |
| Alpha Fencing & Gates NE Limited | Construction | 2025 |
| Alpha Fencing NE Limited | Administrative & support | 2021 |
| Alpha P&P Holdings Ltd | Financial services | 2020 |
| Alpha Properties (NE) Limited | Real estate | 2021 |
| Alpha Walls and Ceilings Ltd | Construction | 2023 |
| Alreet Stays Ltd | Hospitality | 2025 |
| Alrosmil Design Services Ltd | Professional & scientific | 2024 |
| ALS Turkish Barbers Ltd | Other services | 2023 |
| Altay Kurdish Barbers Ltd | Other services | 2026 |
| Altdun Ltd | Real estate | 2021 |
| Althaus Ltd | Real estate | 2025 |
| Altona Coach Services Ltd | Transport & logistics | 2009 |
| Altonaids Mobility Limited | Wholesale & retail | 2000 |
| Altroth Ltd | Real estate | 2018 |
| Altus AI Automation and Consulting Limited | Information & communication | 2024 |
| Alvand Bakery Limited | Wholesale & retail | 2025 |
| Alverstone Mortgages Limited | Financial services | 2021 |
| AM Living (NE) Ltd | Real estate | 2026 |
| AM Rental Solutions Limited | Real estate | 2025 |
| Amandare Solutions Ltd | Administrative & support | 2020 |
| Amara-Nedu Argon Limited | Wholesale & retail | 2025 |
| Amaya Group Ltd | Wholesale & retail | 2017 |
| Amazing GM Ltd | Wholesale & retail | 2019 |
| Amazing Learning Limited | Information & communication | 2000 |
| Amazing Music America Limited | Wholesale & retail | 2018 |