| Adcompletions Ltd | Construction | 2023 |
| Adcott Financial Ltd | Financial services | 2020 |
| Adcott Solutions Ltd | Wholesale & retail | 2018 |
| ADD Solutions Ltd | Construction | 2017 |
| Added Housing Ltd | Real estate | 2020 |
| Addison Properties NE Ltd | Real estate | 2023 |
| Adel Square Ltd | Households | 2024 |
| Adelinacamasoiu Limited | Administrative & support | 2025 |
| Adenkunle Logistics Ltd | Transport & logistics | 2024 |
| Adfai Tech Ltd | Wholesale & retail | 2024 |
| Adil's (Hartlepool) Limited | Hospitality | 2019 |
| Adils Plumbing and Heating Ltd | Construction | 2024 |
| Adils Security Ltd | Other services | 2025 |
| ADM Electrical Services Ltd | Construction | 2017 |
| Admin Accelerator Ltd | Information & communication | 2022 |
| Admissions UK Ltd | Information & communication | 2025 |
| Adnexai Limited | Information & communication | 2025 |
| Adparatio Ltd | Water & waste | 2023 |
| ADS Welding Ltd | Manufacturing | 2020 |
| Adulis Limited | Wholesale & retail | 2020 |
| Advanced Consumer Technology Limited | Administrative & support | 2015 |
| Advanced Electech Services Ltd | Construction | 2025 |
| Advanced Formulations (Europe) Ltd | Wholesale & retail | 1993 |
| Advanced Housing & Utility Services Ltd | Construction | 2024 |
| Advanced Industrial Coatings Ltd | Construction | 2022 |
| Advanced Material Handling Limited | Other services | 2009 |
| Advanced Project Developments Limited | Real estate | 2018 |
| Advanced Protection Group UK Ltd | Administrative & support | 2018 |
| Advanced Rigging Solutions Limited | Professional & scientific | 2019 |
| Advanced Systems Ltd | Wholesale & retail | 2016 |
| Advanced UK Solutions Limited | Construction | 2022 |
| Advanced Utility Solutions Limited | Administrative & support | 2006 |
| Advanced Vehicle Leasing (Stockton) Limited | Financial services | 2004 |
| Advanced Vehicle Leasing Limited | Financial services | 1997 |
| Advent Calendar Online Limited | Information & communication | 2015 |
| Advent Development Holdings Ltd | Financial services | 2012 |
| Advent Developments Adel Limited | Construction | 2020 |
| Advent Developments Limited | Construction | 2006 |
| Advent Developments NE Limited | Construction | 2019 |
| Advent Developments Pudsey Limited | Construction | 2017 |
| Adventures With Abigail Ltd | Health & social care | 2024 |
| Adyn Ltd | Arts & recreation | 2017 |
| AEA Developments Ltd | Construction | 2016 |
| AEB STB Ltd | Administrative & support | 2022 |
| AEM Consultancy Services Ltd | Professional & scientific | 2025 |
| AER Project Resource Limited | Professional & scientific | 2023 |
| AER Project Services Limited | Professional & scientific | 2018 |
| Aero Commerce Limited | Information & communication | 2018 |
| AES Construction Management Consultants Limited | Construction | 2017 |
| Aesthetics by AMO Ltd | Other services | 2021 |
| Aesthetics by Andrea Ltd | Health & social care | 2020 |
| Aesthetics by Sally Ltd | Other services | 2023 |
| AEW Training CIC | Other services | 2023 |
| AF Locum Ltd | Real estate | 2014 |
| AF Property NE Ltd | Real estate | 2024 |
| AF Studio Ltd | Professional & scientific | 2026 |
| Affinity Holding Group Ltd | Financial services | 2021 |
| Affinity Markets Ltd | Financial services | 2022 |
| AFG Carpets & Flooring Ltd | Wholesale & retail | 2026 |
| AFG Meat Ltd | Wholesale & retail | 2025 |
| Afghan.Boutique.Us Ltd | Wholesale & retail | 2025 |
| Africa Food Market and Hair Saloon Ltd. | Hospitality | 2024 |
| Afrochoice CC Ltd | Wholesale & retail | 2026 |
| Afroelegance Fashion Hub CIC | Manufacturing | 2025 |
| Afrokings Barbershop Limited | Other services | 2025 |
| Afronaut Ltd | Arts & recreation | 2021 |
| After Hours Social Limited | Professional & scientific | 2023 |
| AFW Interiors Limited | Wholesale & retail | 2000 |
| Afzal Immigration Limited | Professional & scientific | 2025 |
| AG Barbering Ltd | Other services | 2018 |
| AG Bell Properties Ltd | Real estate | 2025 |
| AG IT Associates Ltd | Information & communication | 2019 |
| AG Roofing Building Ltd | Construction | 2019 |
| AGE UK Teesside Limited | Health & social care | 1987 |
| AGH Wind Ltd | Information & communication | 2017 |
| Agility People Services Limited | Administrative & support | 2008 |
| AGM IT Solutions Limited | Other services | 2015 |
| AGW Property Lettings Limited | Real estate | 2025 |
| AH (M'Bro) Properties Ltd | Real estate | 2022 |
| AH Assets Limited | Administrative & support | 2013 |
| AH Housing Ltd | Real estate | 2023 |
| AH Properties Link Ltd | Real estate | 2020 |
| AH Safety Services Ltd | Professional & scientific | 2023 |
| Ah-Nh Properties Ltd | Real estate | 2017 |
| Ahlulbayt Cultural Association | Education | 2011 |
| Ahsan Locum Ltd | Health & social care | 2016 |
| Ahwat Properties Ltd | Real estate | 2025 |
| AI Properties (Morpeth) Limited | Real estate | 2012 |
| AI Properties (Whitley Bay) Limited | Real estate | 2012 |
| Aiah Ltd | Mining & quarrying | 2025 |
| Aideas Factory Limited | Information & communication | 2024 |
| Aiken Healthcare NE Ltd | Wholesale & retail | 2022 |
| Ainsley Plant Ltd. | Construction | 2015 |
| Air Implementation Ltd | Other services | 2024 |
| Aiuk Holdings Ltd | Financial services | 2021 |
| Aiyan Ltd | Wholesale & retail | 2024 |
| AJ BAG Super Store Ltd | Wholesale & retail | 2024 |
| AJ Crest Ltd | Wholesale & retail | 2026 |
| AJ Lettings & Management (N.E) Ltd | Real estate | 2021 |
| AJ Mech Technical Services Ltd | Professional & scientific | 2022 |