| Amber Integrated Controls and Automation Limited | Manufacturing | 2000 |
| Ameshna Limited | Health & social care | 2010 |
| Amor Care Limited | Administrative & support | 2016 |
| Ampfield Commercial Limited | Real estate | 2014 |
| Ampfield Estates Ltd | Real estate | 2002 |
| Ampfield Liveries Ltd | Agriculture & fishing | 2018 |
| Ampfield Logs Limited | Agriculture & fishing | 2023 |
| Ampfield Management Consulting Limited | Professional & scientific | 2014 |
| ANA Medical Services Limited | Health & social care | 2020 |
| AND YOU CAN Quote ME Ltd | Wholesale & retail | 2023 |
| Andover Buffets Limited | Hospitality | 2015 |
| Andover Cricket Club Limited | Arts & recreation | 2013 |
| Andrew James Associates Limited | Professional & scientific | 2003 |
| Andrew Waring Associates Limited | Professional & scientific | 2002 |
| Anesti Limited | Hospitality | 2018 |
| Angel Floss Ltd | Manufacturing | 2020 |
| Angela Davey Associates Ltd | Professional & scientific | 2011 |
| Angus Tree Surgeons Ltd | Agriculture & fishing | 2019 |
| Animaled Limited | Agriculture & fishing | 2020 |
| Animora Health Ltd | Other services | 2026 |
| Anna Mel-Mo Healthcare Ltd | Health & social care | 2025 |
| AP Art Advisory Ltd | Other services | 2025 |
| Apex Cardiology Ltd | Health & social care | 2019 |
| Apollo Property South Limited | Real estate | 2024 |
| Applemore Early Years Centre Ltd | Education | 2018 |
| Apricate Consulting Ltd | Professional & scientific | 2023 |
| Aquascience Limited | Other services | 2005 |
| Aquastyle Pools Ltd | Construction | 2012 |
| ARA S.V. K9 Ltd | Administrative & support | 2025 |
| Arb-Solute Tree Management Limited | Agriculture & fishing | 2022 |
| Arbwise Limited | Agriculture & fishing | 2015 |
| Arculus Scott Commercial Limited | Real estate | 2021 |
| Arculus Scott Residential Limited | Real estate | 2021 |
| Arendelle Property Investments Limited | Real estate | 2015 |
| Argo Navis Maritime Limited | Professional & scientific | 2013 |
| Argus Accounting Services Ltd | Professional & scientific | 2017 |
| Ariel's Filipino Kitchen Ltd | Hospitality | 2025 |
| Arle Investco Limited | Financial services | 2023 |
| Arle Midco Limited | Financial services | 2023 |
| Arvi Telehealth Ltd | Health & social care | 2023 |
| ASA Business Consulting Ltd | Professional & scientific | 2022 |
| Asaxa Properties Limited | Real estate | 2024 |
| Aserta Ltd | Wholesale & retail | 2026 |
| Ashik Shetty Consulting Ltd | Health & social care | 2014 |
| ASK About Mortgages Limited | Financial services | 2013 |
| Aspin Holdings Limited | Financial services | 2017 |
| Aspin Management Systems Limited | Information & communication | 1984 |
| Aspire Business Development Limited | Professional & scientific | 2017 |
| Aspire Hair Salon Limited | Other services | 2007 |
| Associated Maritime Consultants Limited | Administrative & support | 2017 |
| Asterion Technologies Limited | Information & communication | 2020 |
| Astrix Services Ltd | Professional & scientific | 2020 |
| ASW Electrical Limited | Construction | 2015 |
| ASW Property Maintenance Limited | Administrative & support | 2017 |
| Atherley Cleaners Limited | Other services | 1987 |
| Atoms Electrical Ltd | Construction | 2021 |
| Auntie GI Spices Ltd | Hospitality | 2019 |
| AVB Oncology Limited | Health & social care | 2014 |
| Avenue Medical Limited | Health & social care | 2025 |
| AVI Asbestos Vehicle Inspection Ltd | Water & waste | 2022 |
| Aviation Spares & Repairs Limited | Manufacturing | 2005 |
| Avize Limited | Professional & scientific | 2008 |
| Avocet Medical Services Limited | Health & social care | 2017 |
| Avoria Health Ltd | Other services | 2026 |
| AVP Medical Ltd | Health & social care | 2022 |
| Awbridge Business Consultants Ltd | Professional & scientific | 2018 |
| Awbridge Construction Project Services Ltd | Construction | 2024 |
| Awbury Holdings Ltd | Construction | 2021 |
| AWM Group Limited | Financial services | 2017 |
| AY Aviation Solutions Limited | Administrative & support | 2017 |
| Ayano Spa Limited | Other services | 2019 |
| Ayles Consultancy Limited | Professional & scientific | 2023 |
| AZM Project Services Limited | Administrative & support | 2016 |
| Aztec Fencing Limited | Construction | 2014 |
| B Aimson Ltd | Health & social care | 2023 |
| B H Heating Limited | Energy | 2010 |
| B H M Electrical Services Limited | Construction | 1986 |
| B Southlands Ltd | Professional & scientific | 2015 |
| B&D Electrical Ltd | Construction | 2020 |
| B-Knect Limited | Information & communication | 2020 |
| B-P Clinical Services LLP | | 2024 |
| B. Cole & Sons (Amusements) Limited | Administrative & support | 1963 |
| B.C.E.F. Properties Limited | Construction | 2020 |
| B.C.R.T. Limited | Arts & recreation | 2011 |
| Babbage Developments Limited | Construction | 2018 |
| Back Medicolegal Services Ltd | Health & social care | 2011 |
| BAD Manners Property Limited | Real estate | 2015 |
| Bags Dermatology Limited | Real estate | 2015 |
| Baileys Brickwork Limited | Construction | 2016 |
| Baker Developments Ltd | Real estate | 2020 |
| Banksia (Awbridge) Management Company Limited | Households | 2017 |
| BAP Limited | Real estate | 1994 |
| Bargate Catering Company Limited | Hospitality | 1992 |
| Barkerbarnes & Co Limited | Professional & scientific | 2023 |
| Barling Mews Management Company Limited | Households | 2000 |
| Barnbridge Consulting Limited | Construction | 2019 |
| Barrel to TAP Ltd | Professional & scientific | 2018 |
| Barry Drummond Limited | Wholesale & retail | 2017 |
| Barton Court RTM Company Limited | Households | 2004 |
| Bascombe Carpentry & Construction Limited | Construction | 1988 |