| Abarbistro Limited | Hospitality | 2003 |
| Abbey Polythene Limited | Manufacturing | 2007 |
| Abbeyfield Decorators Ltd | Construction | 2003 |
| Abbeymede Freehold Limited | Households | 2013 |
| Abbeymede Residents Limited | Households | 2002 |
| Abby Clothing and Accessories Ltd | Wholesale & retail | 2025 |
| Abby Healthcare Ltd. | Health & social care | 2021 |
| ABC Inns Ltd | Hospitality | 2026 |
| Abem Healthcare Ltd | Health & social care | 2024 |
| Abery Services Limited | Information & communication | 1999 |
| Abetterwayuk Limited | Professional & scientific | 2025 |
| ABJ’ O Ltd | Health & social care | 2025 |
| ABL Software Ltd | Information & communication | 2012 |
| ABL Tooling Limited | Manufacturing | 2003 |
| Able Drylining Ltd | Construction | 2021 |
| ABM Finance Limited | Professional & scientific | 2017 |
| Above & Beyond Roofing Solutions Ltd | Construction | 2026 |
| ABP Lines Limited | Transport & logistics | 2018 |
| ABS Heating UK Limited | Construction | 2006 |
| ABS Southern Logistics Limited | Transport & logistics | 2011 |
| Abshot Engineering Limited | Manufacturing | 1973 |
| Absolute Aqua Building Contracts Ltd | Administrative & support | 2015 |
| Absolute Carpentry (Southern) Limited | Construction | 2018 |
| Absolute Construction (Southern) Limited | Construction | 2022 |
| Absolute Plumbing Heating & Electrical Ltd | Construction | 2022 |
| Absolute Southern Ltd | Real estate | 2025 |
| AC Life Limited | Administrative & support | 2016 |
| AC Portsmouth Holdings Ltd. | Real estate | 2025 |
| AC Portsmouth Property Ltd | Real estate | 2025 |
| ACA Accounts Ltd | Professional & scientific | 2024 |
| Acaboom Limited | Information & communication | 2013 |
| Acann Limited | Professional & scientific | 2024 |
| ACCELER8.IO Ltd | Information & communication | 2025 |
| Access 2 Drive Limited | Education | 2012 |
| Accessit-Group Ltd | Information & communication | 2019 |
| Acci Airconditioning Ltd | Manufacturing | 2014 |
| Acci Maintenance Ltd | Construction | 2025 |
| Accomodate YOU Ltd | Real estate | 2025 |
| Account Prime Limited | Professional & scientific | 2019 |
| Accountability Recruitment (South) Limited | Administrative & support | 1997 |
| Ace Accommodation Limited | Real estate | 2016 |
| Ace Barber Portsmouth Ltd | Other services | 2023 |
| Ace Developments Southern Ltd | Construction | 2025 |
| Ace DOT Services Limited | Construction | 2015 |
| Ace Films Ltd | Information & communication | 2023 |
| Ace Investment Group LP | | 2023 |
| Ace Virtual Office Ltd | Other services | 2026 |
| Ace Wizard Ltd | Administrative & support | 2014 |
| Acen Food Ltd | Hospitality | 2018 |
| Achieve Heights Services Limited | Health & social care | 2023 |
| Ackworth Road Management Limited | Real estate | 1995 |
| Ackworth Road MOT Centre Limited | Wholesale & retail | 2002 |
| Aclp Solar Limited | Energy | 2025 |
| ACM Construction & Development Ltd | Construction | 2014 |
| Acme Design & Print Ltd | Manufacturing | 2007 |
| Acorn Business Park (Cosham) Management Company Limited | Administrative & support | 1993 |
| Acorn Tax Limited | Other services | 2021 |
| Acorn Valley Ltd | Construction | 2015 |
| ACP (Group) Limited | Financial services | 2012 |
| Acquentis Limited | Administrative & support | 2018 |
| ACS Accountants Ltd | Professional & scientific | 2014 |
| ACS Fire and Security Limited | Manufacturing | 2007 |
| ACS Fire Limited | Construction | 2007 |
| ACS Ports Services Ltd | Professional & scientific | 2024 |
| Actchamp UK Ltd | Wholesale & retail | 2025 |
| Action Finance Limited | Financial services | 2010 |
| ACTIV8 Recruitment Ltd | Administrative & support | 2014 |
| Active Care 24/7 Ltd | Health & social care | 2020 |
| Active Futures Limited | Education | 2022 |
| Active ME 360 C.I.C. | Education | 2018 |
| Active Parcel Distribution (APD) Ltd | Transport & logistics | 2025 |
| Active Property Management (APM) Ltd | Real estate | 2025 |
| Active Simulators Europe Ltd | Arts & recreation | 2019 |
| Active Simulators Limited | Arts & recreation | 2006 |
| Activity Time Limited | Arts & recreation | 1996 |
| AD Property Management (Southern) Ltd | Real estate | 2021 |
| ADA Residential Limited | Real estate | 2026 |
| Adam's Carriage Limited | Other services | 1999 |
| Adamo Transport Ltd | Transport & logistics | 2021 |
| Adapt Cyber Security Ltd | Information & communication | 2025 |
| Adaptation Consultancy and Training Limited | Professional & scientific | 2023 |
| Adcon Hvac Limited | Energy | 2021 |
| Adcredo Construction Ltd | Construction | 2020 |
| ADD Space (UK) Limited | Construction | 2006 |
| Addison Cameron Limited | Financial services | 2019 |
| Addison Way Ltd | Professional & scientific | 2014 |
| Addmire Ltd | Wholesale & retail | 2026 |
| Addo Accounting Ltd | Professional & scientific | 2013 |
| Addob.Projects Ltd | Construction | 2023 |
| Adept Groundwork Services Ltd | Construction | 2025 |
| Adept OIL Fired Heating Limited | Other services | 2011 |
| Aderos Food Ltd | Wholesale & retail | 2026 |
| Adesquare and Sons Ltd | Health & social care | 2025 |
| ADJ Group Ltd | Construction | 2018 |
| ADK Building Services Ltd | Construction | 2018 |
| Admar Communications Limited | | 1987 |
| Admiral Care Ltd | Health & social care | 2010 |
| Admirals Place Freehold Limited | Households | 2013 |
| Admirals Place Residents Limited | Households | 2002 |
| Admirals Walk (Seaford) Limited | Real estate | 1991 |