| AAH Offshore Services Ltd | Construction | 2025 |
| AAJ Commercialcleaning Services Ltd | Administrative & support | 2023 |
| AAM & Sons Limited | Education | 2004 |
| AAM Northern Ltd | Financial services | 2025 |
| Aamss Limited | Real estate | 2020 |
| Aaris Property Ltd | Real estate | 2024 |
| AB Building Design Limited | Professional & scientific | 2007 |
| AB Classic Services Limited | Wholesale & retail | 2020 |
| AB1 Design Ltd | Professional & scientific | 2022 |
| Abacus Financial Accounting Ltd | Professional & scientific | 2006 |
| Abacusbean Limited | Professional & scientific | 2018 |
| Abacusbean Tax Limited | Professional & scientific | 2021 |
| Abadgar Enterprise Limited | Hospitality | 2026 |
| Abbey Garage Doors (UK) Limited | Construction | 2007 |
| Abbey Grace Consulting Ltd | Professional & scientific | 2024 |
| Abbey Inspection Ltd | Professional & scientific | 2022 |
| Abbeyfield Guest House Ltd. | Hospitality | 2023 |
| Abby and MAC Limited | Real estate | 2025 |
| Abella Vici Limited | Wholesale & retail | 2020 |
| Abgawood Medical Ltd | Health & social care | 2023 |
| ABH1 Limited | Financial services | 2024 |
| ABH2 Limited | Financial services | 2024 |
| ABH3 Limited | Financial services | 2024 |
| ABH4 Limited | Financial services | 2024 |
| Abiye Ltd | Administrative & support | 2023 |
| Abound Property Ltd | Real estate | 2021 |
| Above and Beyond Homes NE Ltd | Construction | 2024 |
| Above and Beyond Windows Limited | Manufacturing | 2022 |
| Abpmc Ltd | Professional & scientific | 2026 |
| Abrahams FAM Ltd | Health & social care | 2022 |
| Abrahams FAM Properties Ltd | Real estate | 2023 |
| ABS Lifting Solutions Limited | Construction | 2020 |
| Absolute Commercial Interiors Holdings Limited | Financial services | 2020 |
| Absolute Commercial Interiors Limited | Construction | 2006 |
| Abyss Safety Ltd | Construction | 2026 |
| AC at Teesside Ltd | Hospitality | 2025 |
| AC Industrial Services Limited | Professional & scientific | 2023 |
| AC NDT Inspection Services Limited | Construction | 2023 |
| ACC Catering Ltd | Hospitality | 2024 |
| Access Holdings Group Limited | Professional & scientific | 2016 |
| Access Lettings Limited | Real estate | 2015 |
| Access Loft Conversions Limited | Construction | 2016 |
| Access Lofts Group Limited | Other services | 2014 |
| Access Racing Limited | Arts & recreation | 2016 |
| Access UK Group Ltd | Other services | 2025 |
| Accessibility Bathrooms Ltd | Professional & scientific | 2019 |
| Accolade Lettings Limited | Real estate | 2012 |
| Accounts & Business Management Limited | Professional & scientific | 2007 |
| Ace Community Support CIC | Education | 2026 |
| Ace Concrete Flooring Solutions Ltd | Construction | 2019 |
| Ace Data Solutions Limited | Information & communication | 2012 |
| Ace Music Ltd | Information & communication | 2026 |
| Ace Sales & Lettings Ltd | Real estate | 2021 |
| Aceda Limited | Information & communication | 2002 |
| Acfl Asbestos Limited | Construction | 2019 |
| Acklam Couriers Limited | Transport & logistics | 2023 |
| Ackroyd Engineering Limited | Professional & scientific | 2025 |
| Ackroyd Properties Ltd | Real estate | 2021 |
| ACL Property Services(Ne) Ltd | Construction | 2023 |
| Acland Homes Ltd | Real estate | 2018 |
| Acorn Snagging Limited | Construction | 2025 |
| Acornarb Limited | Agriculture & fishing | 2018 |
| Acouchi Limited | Real estate | 2017 |
| ACT Products Limited | Manufacturing | 2009 |
| Active Business Consultancy Holdings Ltd | Administrative & support | 2025 |
| Active Business Consultancy Ltd | Administrative & support | 2021 |
| Active Communities Teesside CIC | Arts & recreation | 2025 |
| Active Financial Planners Limited | Financial services | 2000 |
| Active Mobility Centre Limited | Wholesale & retail | 1997 |
| Active Physio Care Limited | Financial services | 2024 |
| Active Pictures LLP | | 2015 |
| Acton TEC Services Limited | Professional & scientific | 2014 |
| ACV Property Ltd | Real estate | 2024 |
| Adam ALI Iqbal Ltd | Administrative & support | 2023 |
| Adam Armitage Limited | Health & social care | 2015 |
| Adam JR Ltd | Financial services | 2025 |
| Adam Smith Property Services Ltd | Construction | 2026 |
| Adapt Financial Planning Limited | Financial services | 2015 |
| Adaptive Medical Limited | Information & communication | 2021 |
| Adavis Limited | Professional & scientific | 2014 |
| ADB Larsen Logistics Limited | Transport & logistics | 2025 |
| ADD Colours Ltd | Hospitality | 2019 |
| Adder Security Ltd | Administrative & support | 2014 |
| Addible Ltd | Professional & scientific | 2020 |
| Addison Developments (NE) Ltd | Construction | 2021 |
| Addison Haulage North East Ltd. | Transport & logistics | 2022 |
| Adept Electrical Solutions Ltd | Manufacturing | 2016 |
| Adept Properties Limited | Real estate | 2018 |
| Adgh Contracts Limited | Administrative & support | 2014 |
| ADI Logistics Solutions Limited | Transport & logistics | 2025 |
| Adis (NE) Ltd | Administrative & support | 2014 |
| Adjl Technical Services Ltd | Construction | 2025 |
| Adlix Ltd | Information & communication | 2025 |
| ADN Access Ltd | Construction | 2024 |
| Adnan's Stores Ltd | Wholesale & retail | 2018 |
| ADO Repairs Limited | Wholesale & retail | 2024 |
| Adra Engineering Ltd | Manufacturing | 2021 |
| Adregis Investments Limited | Education | 2011 |
| Adrian Stoian Construction Ltd | Construction | 2026 |
| Adroit Utilities Limited | Construction | 2012 |