| ACL Plumbing Services Ltd | Construction | 2026 |
| ACL Waste Ltd | Water & waste | 2024 |
| ACM Care Limited | Administrative & support | 2024 |
| Acnl Consultants Limited | Construction | 1996 |
| Acomb Properties Limited | Real estate | 2024 |
| Acomb PUB Company Ltd | Hospitality | 2024 |
| Acorn Beauty Jesmond Limited | Other services | 2023 |
| Acorn Design and Instalations Ltd | Construction | 2013 |
| Acorn Event Safety Ltd | Arts & recreation | 2024 |
| Acorn Food Ltd | Hospitality | 2024 |
| Acorn Group Global Ltd | Wholesale & retail | 2016 |
| Acorn North Property Ltd | Real estate | 2023 |
| Acos Renewable Energy Co. Ltd | Construction | 2011 |
| ACP Wealth Management Limited | Financial services | 2016 |
| Acquagas Engineers Ltd | Construction | 2021 |
| Acquaverde Ltd | Other services | 2017 |
| Acropolis Franchise Limited | Wholesale & retail | 2022 |
| Acropolis Jesmond Ltd | Hospitality | 2021 |
| Acropolis One Ltd | Hospitality | 2021 |
| Acropolis SN Ltd | Hospitality | 2020 |
| Acropolis Street Food (BTR) Limited | Hospitality | 2019 |
| Acropolis Street Food (Catering) Ltd | Manufacturing | 2018 |
| Acropolis Street Food (Grainger Market) Limited | Hospitality | 2019 |
| Acropolis Street Food (Quayside) Limited | Hospitality | 2017 |
| Acropolis Street Food (Tynemouth) Limited | Hospitality | 2019 |
| Acropolis Street Food Limited | Wholesale & retail | 2016 |
| Acropolis Toon Ltd | Hospitality | 2025 |
| Acropolis UK Fest Ltd | Wholesale & retail | 2021 |
| Acropolis VYF Ltd | Hospitality | 2022 |
| Acropolisuk Ltd | Hospitality | 2020 |
| ACS Flooring Ltd | Construction | 2025 |
| ACS Services N.E Ltd | Wholesale & retail | 2024 |
| ACT Projects Ltd. | Administrative & support | 2002 |
| ACT! Software Limited | Information & communication | 2013 |
| Acta Marine UK Limited | Administrative & support | 2021 |
| Acta Sanctorum Ltd | Wholesale & retail | 2023 |
| Actdesign (UK) Ltd | Information & communication | 2014 |
| Actif Consulting Ltd | Professional & scientific | 2021 |
| Acting UP Childrens Theatre Company Limited | Arts & recreation | 2014 |
| Action 4 Equality (Scotland) Limited | Other services | 2005 |
| Action Foundation | Administrative & support | 2009 |
| Active Forms Ltd | Wholesale & retail | 2026 |
| Active Future Newcastle CIC | Education | 2024 |
| Active IQ Limited | Education | 2003 |
| Active Northumberland | Arts & recreation | 2013 |
| Active Northumberland Trading Limited | Hospitality | 2014 |
| Active SEO Consultants Limited | Information & communication | 2024 |
| Activepraise Limited | Wholesale & retail | 1992 |
| Activity Score Limited | Information & communication | 2024 |
| ACTU8 (Thps) Ltd | Administrative & support | 2015 |
| Acuman Business Services Limited | Professional & scientific | 2010 |
| Acumen Accounting Limited | Professional & scientific | 2020 |
| Acumen South Shields Limited | Professional & scientific | 2024 |
| Acupaye Limited | Administrative & support | 2024 |
| Acutemp Airconditioning Limited | Construction | 2021 |
| AD Astra Recruitment Ltd | Administrative & support | 2019 |
| AD Holdings (NE) Ltd | Real estate | 2023 |
| AD Murum Limited | Real estate | 2022 |
| AD North Ltd | Information & communication | 2022 |
| ADA Innovation Group Ltd | Professional & scientific | 2026 |
| ADA Motors UK Limited | Wholesale & retail | 2024 |
| Adair Property Solutions Ltd | Real estate | 2019 |
| Adam Armstrong Engineering Ltd | Professional & scientific | 2020 |
| Adam Branson Editorial Ltd | Information & communication | 2019 |
| Adam Goldstone Holdings Limited | Financial services | 2024 |
| Adam Holding INT Ltd | Construction | 2018 |
| Adam James Dean Ltd | Administrative & support | 2019 |
| Adam Johnson Promotions Limited | Professional & scientific | 2007 |
| ADAM2020 Ltd | Information & communication | 2020 |
| Adamo Giuseppe Ltd | Wholesale & retail | 2025 |
| Adams Cars (NE) Ltd | Transport & logistics | 2020 |
| Adams Family Group Limited | Education | 2019 |
| Adams Jenkins Properties Limited | Real estate | 2011 |
| Adams Northeast Properties Ltd | Real estate | 2016 |
| Adamson Electrical Services Ltd | Construction | 2022 |
| Adamson Holding Company Limited | Real estate | 2015 |
| Adamson Office Developments Limited | Construction | 2006 |
| Adapt Your Home for Life Ltd | Professional & scientific | 2020 |
| Adaptive Digital Knowledge Ltd | Information & communication | 2025 |
| ADB Health Solutions Limited | Professional & scientific | 2019 |
| ADC Advisory Ltd | Administrative & support | 2025 |
| ADC Building & Maintenance Ltd | Construction | 2021 |
| ADC Power Ltd | Professional & scientific | 2018 |
| Adcomat Storage Ltd | Other services | 2019 |
| ADD Strategy Ltd | Professional & scientific | 2015 |
| Adda Hospitality Ltd | Hospitality | 2023 |
| Addere Valorem Ltd | Professional & scientific | 2012 |
| Adderstone (200) Limited | Financial services | 2019 |
| Adderstone (201) Limited | Real estate | 2017 |
| Adderstone (207) Limited | Real estate | 2018 |
| Adderstone (208) Limited | Real estate | 2018 |
| Adderstone (209) Limited | Real estate | 2018 |
| Adderstone (210) Limited | Real estate | 2001 |
| Adderstone (213) Limited | Real estate | 2017 |
| Adderstone (214) Limited | Real estate | 2018 |
| Adderstone (216 COM) Limited | Real estate | 2020 |
| Adderstone (217) Limited | Real estate | 2020 |
| Adderstone (Falkland Islands) Limited | Financial services | 2024 |
| Adderstone (Ralph) Developments Limited | Construction | 2014 |
| Adderstone 17 Management Company Limited | Real estate | 2001 |