| Adeolu Ltd | Health & social care | 2025 |
| Adikus Ltd | Transport & logistics | 2025 |
| ADL Components Limited | Wholesale & retail | 2011 |
| ADM Building Ltd | Construction | 2020 |
| Admiral Safety Limited | Professional & scientific | 2011 |
| Adnix Inc Ltd | Other services | 2024 |
| Adrian Driving Ltd | Transport & logistics | 2015 |
| Adryan&Miky Ltd | Wholesale & retail | 2024 |
| ADS Airsoft Limited | Wholesale & retail | 2024 |
| ADS Minimarket Ltd | Wholesale & retail | 2025 |
| Adshaq Ltd | Public administration | 2022 |
| Advance Machine Tool Services Limited | Professional & scientific | 2006 |
| Advanced Acoustics Limited | Wholesale & retail | 2009 |
| Advanced Cladding Installations Limited | Agriculture & fishing | 1997 |
| Advanced Painting Solutions Ltd | Construction | 2021 |
| Advanced Video Analytics Limited | Administrative & support | 2025 |
| Aess UK (Notts) Ltd | Construction | 2016 |
| Aesthetics by DR Seetal Ltd | Other services | 2024 |
| Aesthetics on the Hill Limited | Health & social care | 2024 |
| Aesthetix Property Care Ltd | Administrative & support | 2023 |
| AEW Precision Ventilation Limited | Construction | 2021 |
| AF1 Services Ltd | Wholesale & retail | 2018 |
| AFC Mansfield Limited | Arts & recreation | 2012 |
| Affiliates GET Seen Here Ltd | Information & communication | 2010 |
| Affinity Property Partners Ltd | Real estate | 2026 |
| AG Corporate Law Limited | Professional & scientific | 2022 |
| AG Integrated Services Ltd | Professional & scientific | 2023 |
| AG Projects Ltd | Real estate | 2019 |
| Agapie Transport Ltd | Transport & logistics | 2023 |
| AGG Electrical Safety Testing Limited | Construction | 2007 |
| Agile Pronunciation Teachers Ltd | Extraterritorial | 2020 |
| Agility Accommodation Ltd | Real estate | 2017 |
| AGM Coaching Ltd | Education | 2025 |
| Agron & Landi Limited | Wholesale & retail | 2018 |
| Agzarose Ltd | Transport & logistics | 2023 |
| Ahyj Limited | Health & social care | 2024 |
| AI Buck Ltd | Transport & logistics | 2021 |
| Aidal Limited | Wholesale & retail | 2023 |
| AIM Architecture Limited | Professional & scientific | 2014 |
| Ainstable Ltd | Transport & logistics | 2022 |
| Aipawer Ltd | Information & communication | 2026 |
| Airo Sail Ltd | Transport & logistics | 2022 |
| Airport Information Systems Limited | Information & communication | 1990 |
| Airseal Solutions Limited | Construction | 2009 |
| Airwave Travel Ltd | Transport & logistics | 2024 |
| Aither Brewery Ltd | Manufacturing | 2022 |
| Ajea Ltd | Real estate | 2019 |
| AJI Services Ltd | Administrative & support | 2024 |
| AJP Sales Limited | Wholesale & retail | 2017 |
| AJS Builders Ltd | Construction | 2020 |
| AJS Event Decor Limited | Hospitality | 2025 |
| AJS Paving Ltd | Construction | 2017 |
| AJW Joinery (Mansfield) Limited | Construction | 2017 |
| AK PFP Ltd | Construction | 2026 |
| AK Vogue Ventures Ltd | Wholesale & retail | 2024 |
| AK1 Developments Ltd | Real estate | 2024 |
| AK1 Rentals Ltd | Real estate | 2026 |
| AK47 Digital Productions Limited | Extraterritorial | 2022 |
| Akar Bookkeeping Services Ltd | Professional & scientific | 2018 |
| AKD Mansfield Ltd | Real estate | 2020 |
| Akim Transport Ltd | Transport & logistics | 2025 |
| AKN Stores PVT Ltd | Wholesale & retail | 2024 |
| AKR Investments Ltd | Other services | 2024 |
| AKT Professional Limited | Construction | 2021 |
| Alan Paine Knitwear Limited | Wholesale & retail | 2005 |
| Alchemette Investments Ltd | Real estate | 2012 |
| Alchemette Limited | Real estate | 2000 |
| Alchera Group Ltd | Wholesale & retail | 2024 |
| Aldeburgh Holdings Limited | Administrative & support | 2018 |
| Aldray Ltd | Health & social care | 2022 |
| Aldrin Limited | Professional & scientific | 2011 |
| Alensa Limited | Wholesale & retail | 2018 |
| Alert Holdings Ltd | Financial services | 2026 |
| ALERT2 Ltd | Construction | 2020 |
| Alex Akabreezy Limited | Transport & logistics | 2024 |
| Alexander Wray & Co Limited | Financial services | 2003 |
| Alexander Wray Holdings Limited | Extraterritorial | 2010 |
| Alexis Transport Limited | Transport & logistics | 2024 |
| Alexxa Ltd | Transport & logistics | 2024 |
| ALI Cool CUT Limited | Other services | 2025 |
| ALI Door Ltd | Manufacturing | 2024 |
| Alistair Townsend Limited | Professional & scientific | 2017 |
| ALL About Civils Ltd | Construction | 2022 |
| ALL About Skills Ltd | Administrative & support | 2024 |
| ALL Gutter Services Ltd | Administrative & support | 2025 |
| ALL Routes Limited | Transport & logistics | 2016 |
| ALL Seasons Tree & Garden Services Ltd | Administrative & support | 2025 |
| Allandale News Limited | Wholesale & retail | 2019 |
| Allied Home and DRY Limited | Construction | 2018 |
| Allrac Limited | Other services | 2023 |
| Allseasons Installations Limited | Construction | 2013 |
| Allton Warping Limited | Manufacturing | 1997 |
| Allure Photography Limited | Information & communication | 2014 |
| Allwood Property Developments Ltd | Real estate | 2020 |
| Alma Supermarket Leics Ltd | Wholesale & retail | 2020 |
| Almc Ventures Ltd | Wholesale & retail | 2024 |
| Alona Mikucka PMU Ltd | Other services | 2024 |
| Alonso Property Investments Limited | Real estate | 2023 |
| Alpha Developments Stockport Ltd | Construction | 2020 |
| Alpha Team Publishing Ltd | Information & communication | 2023 |