| A1 Total Plumbing Ltd | Other services | 2009 |
| A1 UK Contractors Ltd | Construction | 2021 |
| A1PHA Security Services Ltd | Financial services | 2021 |
| A2 Shop Limited | Wholesale & retail | 2025 |
| A2B Automotive Ltd | Wholesale & retail | 2025 |
| A2B Southampton Taxi Ltd | Transport & logistics | 2022 |
| A2Z Construction and Steel Fabrications Portsmouth Limited | Manufacturing | 2024 |
| A3H Hospitality Limited | Hospitality | 2026 |
| A4 Real Estate Limited | Real estate | 2022 |
| AA & FA Limited | Real estate | 2023 |
| AA & FA Newco 1 Limited | Professional & scientific | 2020 |
| AA Hamptons Investments Limited | Education | 2017 |
| AA1971 Investments Ltd | Real estate | 2025 |
| Aaars Ltd | Administrative & support | 2019 |
| AAB Cars Ltd | Wholesale & retail | 2024 |
| AAB Consultants Ltd | Information & communication | 2021 |
| AAJ Property Services Limited | Real estate | 2015 |
| AAK Foods Ltd | Hospitality | 2016 |
| Aakarsh Technologies Limited | Information & communication | 2023 |
| Aamnah & Eashal Ltd | Hospitality | 2025 |
| AAP3 Limited | Information & communication | 1997 |
| Aapcom Ltd | Administrative & support | 2023 |
| AAR Nexus Limited | Wholesale & retail | 2024 |
| Aardvark Studios Ltd | Information & communication | 2021 |
| Aargus Security Technologies Limited | Administrative & support | 2001 |
| Aark Solutions Limited | Information & communication | 2011 |
| Aaron Cooper Racing Ltd | Manufacturing | 2023 |
| Aaron Evans Automotive Limited | Wholesale & retail | 2025 |
| Aaron M Property Ltd | Real estate | 2012 |
| Aaron Martin Football Academy Ltd | Education | 2023 |
| Aaru Cleaning Limited | Administrative & support | 2025 |
| Aaryroam Ltd | Administrative & support | 2015 |
| Aarzan Ltd | Wholesale & retail | 2016 |
| Aase Architecture Limited | Professional & scientific | 2025 |
| Aasha (Property) Limited | Real estate | 2022 |
| Aask Consultancy Ltd | Professional & scientific | 2024 |
| Aasl Ltd | Hospitality | 2024 |
| Aatimaa Ltd | Wholesale & retail | 2017 |
| AB Compliance Limited | Administrative & support | 2025 |
| AB Dent Limited | Health & social care | 2017 |
| AB Event Medical Services Limited | Health & social care | 2023 |
| AB Financial Services Ltd | Financial services | 2023 |
| AB Welding Services Ltd | Manufacturing | 2020 |
| Ab-Cam Solutions Ltd | Information & communication | 2026 |
| ABA Clinic Limited | Health & social care | 2012 |
| Abacus Payroll Services Ltd | Transport & logistics | 2024 |
| Abas Investments Limited | Financial services | 2024 |
| Abayomihealthcare Ltd | Health & social care | 2022 |
| Abba Wildern Driver Training Limited | Other services | 2022 |
| Abbas South Limited | Construction | 2025 |
| Abbattis Risk Management Limited | Administrative & support | 2025 |
| Abbey Garden Buildings Limited | Wholesale & retail | 2015 |
| Abbey Grab BAG Ltd | Water & waste | 2021 |
| Abbey Limos Limited | Transport & logistics | 2009 |
| Abbey Marine Services Limited | | 1999 |
| Abbey Preservation-South Ltd | Extraterritorial | 2013 |
| Abbey Property Services South Ltd | Construction | 2026 |
| Abbey Roofing and Cladding Ltd | Construction | 2011 |
| Abbey Tea Limited | Wholesale & retail | 2014 |
| Abbey Tyres (Bishops Waltham) Limited | Wholesale & retail | 2007 |
| Abbey Vehicle Rental Limited | Administrative & support | 2011 |
| Abbey Way Property Limited | Real estate | 2011 |
| Abbeyplans Limited | Wholesale & retail | 2021 |
| Abbott Commerce Ltd | Wholesale & retail | 2026 |
| Abbott Professional Services Limited | Professional & scientific | 2013 |
| Abbotts Court Freehold Limited | Households | 2009 |
| Abbotts House Residents Limited | Households | 1999 |
| Abbotts Langley Nominee Limited | Professional & scientific | 2015 |
| Abby Shacklock Coaching and Advisory Ltd | Professional & scientific | 2026 |
| ABC Alternative Analysis Ltd | Extraterritorial | 2020 |
| ABC Global Recycling Ltd | Construction | 2012 |
| ABC Heatpumps Limited | Construction | 2018 |
| ABC Language and Culture Centre Limited | Education | 2014 |
| ABC Optimal Ltd | Extraterritorial | 2020 |
| ABC Salon Marketing Limited | Professional & scientific | 2010 |
| ABD Supplies Limited | Wholesale & retail | 2010 |
| Abdc Hooper Holdings Ltd | Financial services | 2023 |
| ABG Scaffolding Domestic&Hire Limited | Construction | 2017 |
| ABG Scaffolding Limited | Construction | 2014 |
| ABH Electrical Ltd | Construction | 2017 |
| Abhaile Ltd | Construction | 2018 |
| Abhb Ltd | Wholesale & retail | 2025 |
| ABI Flynn Equestrian Services Ltd | Agriculture & fishing | 2023 |
| Abicad Limited | Administrative & support | 1997 |
| Abigail Laser and Skin Care Ltd | Other services | 2023 |
| Abigail Nicolaou Aesthetics Ltd | Other services | 2021 |
| Abigail Nicolaou Property Ltd | Real estate | 2025 |
| Ability Projects Limited | Manufacturing | 2000 |
| ABJ Home Improvements Limited | Construction | 2018 |
| ABL Executive Ltd | Administrative & support | 2021 |
| Ablaze Healthcare Limited | Health & social care | 2022 |
| Able Install Ltd | Construction | 2010 |
| Able Plumbing (Hampshire) Limited | Construction | 2020 |
| Able Plumbing and Drainage Limited | Construction | 2025 |
| ABM Electrical Solutions Ltd | Manufacturing | 2020 |
| ABM EV Charging Solutions Ltd | Manufacturing | 2020 |
| ABM Solutions Group Ltd | Financial services | 2020 |
| ABM Store Ltd | Wholesale & retail | 2025 |
| Abni AI Ltd | Information & communication | 2026 |
| Aboard Boat Coaching Limited | Education | 2018 |