| Austinsglazing,Buildingandmaintenancecontractor Ltd | Construction | 2021 |
| Autavia Swanmore Limited | Real estate | 2025 |
| Authenticproductslimited Ltd | Wholesale & retail | 2026 |
| Auto Coelho Limited | Wholesale & retail | 2015 |
| Auto Diagnostic Solutions Ltd | Administrative & support | 2016 |
| Auto Electrix Group Ltd | Financial services | 2025 |
| Auto Master Mobile Services Limited | Wholesale & retail | 2025 |
| Auto Repair Shop Ltd | Wholesale & retail | 2019 |
| Auto Skills UK Recruitment Ltd | Administrative & support | 2017 |
| Autobot Mobile Mechanic Services Ltd | Wholesale & retail | 2023 |
| Autocare 365 Limited | Wholesale & retail | 2014 |
| Autocare 365 Properties Ltd | Real estate | 2026 |
| Autolynx Garage Limited | Wholesale & retail | 2011 |
| Automated Environments Ltd | Construction | 2022 |
| Automated Messaging Systems Limited | Information & communication | 1992 |
| Automated Systems Maintenance Ltd | Construction | 2015 |
| Automation Consultancy Group Limited | Manufacturing | 2016 |
| Automotive Energy Solutions Ltd | Manufacturing | 2024 |
| Automotive Online Ltd | Financial services | 2012 |
| Autosteps Ltd | Wholesale & retail | 2019 |
| Autotech Garage Ltd | Wholesale & retail | 2023 |
| Autumn Court (Poole) Limited | Households | 2002 |
| Autumn Views Limited | Financial services | 2002 |
| AUX IT Solutions Ltd | Information & communication | 2017 |
| Av-Sim Limited | Manufacturing | 2025 |
| Avalanche Consult Ltd | Information & communication | 2022 |
| Avalon Cafe Limited | Hospitality | 2015 |
| Avalon Estates Ltd | Real estate | 2018 |
| Avani Ventures Limited | Real estate | 2021 |
| Avantgarde Carpentry Installations Ltd | Construction | 2018 |
| Avaris Media Limited | Professional & scientific | 2022 |
| Avcomit Limited | Other services | 2019 |
| Avec Trade Limited | Extraterritorial | 2019 |
| Avelia Ltd | Hospitality | 2024 |
| Avenet Accountancy Ltd | Professional & scientific | 2019 |
| Avenue House Lymington Limited | Health & social care | 2006 |
| Averra Living Ltd | Wholesale & retail | 2026 |
| Aviastra Flight Charter Ltd | Transport & logistics | 2009 |
| Aviate Training Solutions Limited | Professional & scientific | 2021 |
| Aviemore (Bournemouth) Limited | Real estate | 1987 |
| Aviette Estates Limited | Real estate | 2018 |
| Aviette Limited | Transport & logistics | 2013 |
| Avila Property Investments Limited | Real estate | 2023 |
| Avius Ltd | Information & communication | 2006 |
| Aviver Limited | Construction | 2003 |
| AVO Electrical Contractors Ltd | Construction | 2024 |
| Avon Castle Limited | Households | 2010 |
| Avon Gardens Management Limited | Professional & scientific | 2007 |
| Avon House Flats Management Company (Bournemouth) Limited | Households | 1974 |
| Avon Lodge RTM Company Limited | Households | 2007 |
| Avon Plywood Limited | Manufacturing | 1983 |
| Avon Sands Management Company Limited | Households | 2001 |
| Avon Self Storage Limited | Real estate | 2000 |
| Avosie Co Ltd | Wholesale & retail | 2026 |
| AVR Building Service Ltd | Construction | 2021 |
| Avtek Ltd | Manufacturing | 2024 |
| AW Services South Ltd | Construction | 2025 |
| Away & Stay Ltd | Real estate | 2023 |
| AWE Recruitment Ltd | Administrative & support | 2025 |
| Aweswell Limited | Professional & scientific | 2011 |
| Awit Ltd | Information & communication | 2024 |
| AWM Consultants (Dorset) Limited | Professional & scientific | 2014 |
| Awyl Ltd | Hospitality | 2025 |
| Axiomatix Ltd | Education | 2011 |
| Axiomx Ltd | Transport & logistics | 2025 |
| Axis Living Ltd | Hospitality | 2025 |
| Axminster View Ltd | Construction | 2015 |
| AXQ Ltd | Wholesale & retail | 2024 |
| AXU Anghel Ltd | Manufacturing | 2015 |
| Ay&Blk Limited | Transport & logistics | 2021 |
| AYM Management Consultancy Ltd | Professional & scientific | 2024 |
| Aynsford Manor Residents Company Limited | Real estate | 1975 |
| Ayoade Adeniyi Limited | Real estate | 2023 |
| Aypeck Limited | Wholesale & retail | 2014 |
| AYR Handcarwash Limited | Administrative & support | 2019 |
| Ayrosiaa Limited | Wholesale & retail | 2023 |
| Ayrton & Co Ltd | Water & waste | 2024 |
| Ayshaascar Care Ltd | Health & social care | 2025 |
| Azalea Court (Bournemouth) Management Company Limited | Households | 2001 |
| Azalea Court Freehold Limited | Households | 2010 |
| Azalea Court Management Limited | Households | 2002 |
| Azalea Park Freehold Limited | Households | 2012 |
| Azaleas RTM Company Limited | Households | 2024 |
| Azirome Ltd | Manufacturing | 2016 |
| AZS Holdings Limited | Other services | 2018 |
| Aztec D G Limited | Construction | 2019 |
| Aztec Green Ltd | Real estate | 2024 |
| Azul LA MAR Limited | Wholesale & retail | 2025 |
| Azure Beach Hotel Ltd | Hospitality | 2024 |
| Azure Plumbing & Heating (UK) Limited | Construction | 2014 |
| Azures Investments Limited | Other services | 2020 |
| Azuretec Ltd | Professional & scientific | 2025 |
| Azvi Group Ltd | Professional & scientific | 2025 |
| B & G Fire and Security Ltd | Manufacturing | 1975 |
| B & H Properties Southern Limited | Real estate | 2006 |
| B & R Textiles Limited | Wholesale & retail | 1975 |
| B J Smith Holdings Ltd | Administrative & support | 2025 |
| B K a Enterprise Limited | Real estate | 2020 |
| B M Custom Property Care LLP | | 2024 |
| B P M P Limited | Real estate | 2011 |