| Apex Strategic Services Ltd | Information & communication | 2025 |
| Apex Transit Services Ltd | Wholesale & retail | 2024 |
| Apex Tree Specialists LLP | | 2015 |
| Apex Window Cleaning & Services Limited | Administrative & support | 2017 |
| Apexbyte Consulting Limited | Information & communication | 2024 |
| Apexflooringsupplies Ltd | Wholesale & retail | 2019 |
| APH Financial Management Services Limited | Financial services | 2005 |
| Apheresis Consulting Services Limited | Professional & scientific | 2025 |
| Apieceofcate Ltd | Hospitality | 2017 |
| Apkotransport Ltd | Transport & logistics | 2025 |
| APL Performance Limited | Wholesale & retail | 2024 |
| APL Plastering Limited | Construction | 2019 |
| Apms Properties Limited | Real estate | 2025 |
| APN Electrical Limited | Construction | 2024 |
| Apollo Construction Projects Ltd | Construction | 2020 |
| Apollo Installations (UK) Limited | Construction | 2014 |
| Apollona Development Ltd | Real estate | 2022 |
| Apollonia Studios Limited | Wholesale & retail | 2018 |
| Apollonian Software Limited | Information & communication | 2025 |
| Apostrophe Pubs Limited | Hospitality | 1963 |
| Appacar UK Ltd | Information & communication | 2021 |
| Appleton Holdings Limited | Real estate | 2020 |
| Applicationz Limited | Extraterritorial | 2014 |
| Applied Race Solutions Limited | Wholesale & retail | 2009 |
| Appointlyco Ltd | Administrative & support | 2025 |
| Appraiseye Limited | Information & communication | 2024 |
| Appy Zebra Limited | Information & communication | 2014 |
| Aprender Viviendo Ltd | Education | 2019 |
| Aprozar Daniel Ltd | Wholesale & retail | 2019 |
| APS Infinity Limited | Transport & logistics | 2018 |
| APS Motors Ltd | Wholesale & retail | 2022 |
| Apsis Sourcing Ltd | Construction | 2019 |
| Apvido Ltd | Transport & logistics | 2022 |
| Aqua Blue Properties Ltd | Real estate | 2025 |
| Aqua Include Academy Ltd | Education | 2024 |
| Aqua Include Ltd | Education | 2018 |
| Aquacoach Limited | Education | 2011 |
| Aquatherm Solutions Limited | Administrative & support | 2022 |
| Aquaveil Global Ltd | Wholesale & retail | 2026 |
| Aquaworks Plumbing & Heating Limited | Construction | 2003 |
| AR & NAM Medical Ltd | Wholesale & retail | 2021 |
| AR & NAM Renovations Ltd | Construction | 2024 |
| AR 123 Ltd | Construction | 2017 |
| AR Electrical & Building Maintenance Ltd | Construction | 2025 |
| AR Fire & Security Systems Limited | Administrative & support | 2018 |
| AR Ledger Solutions Limited | Professional & scientific | 2021 |
| AR Performance & Parts Ltd | Wholesale & retail | 2023 |
| AR Security Systems (Holdings) Ltd | Administrative & support | 2023 |
| AR Security Systems Ltd | Administrative & support | 2006 |
| AR Used Cars Ltd | Wholesale & retail | 2020 |
| ARA Motors Limited | Wholesale & retail | 2023 |
| ARA Spa & Leisure Services Limited | Professional & scientific | 2025 |
| Aragon Land and Planning Ltd | Administrative & support | 2006 |
| Aramid Contracts Ltd | Professional & scientific | 2011 |
| Araye Ltd | Professional & scientific | 2023 |
| ARB Trades Ltd | Wholesale & retail | 2023 |
| Arbez Finishing Ltd | Construction | 2018 |
| Arbor Land Limited | Construction | 2026 |
| Arbor Land Partners Limited | Construction | 2025 |
| Arbormaster Tree and Forestry Services Ltd | Extraterritorial | 2014 |
| Arbour Properties Limited | Real estate | 2023 |
| ARC Developers Ltd | Construction | 2021 |
| Arcan Limited | Hospitality | 2024 |
| Arch Joinery and Consultancy Limited | Construction | 2014 |
| Archer Agency Ltd | Professional & scientific | 2011 |
| Archer Van DEN Broeck Limited | Professional & scientific | 2006 |
| Archimedes Consulting Limited | Professional & scientific | 2001 |
| Architect Bedford Ltd | Professional & scientific | 2025 |
| Archive 75 Ltd | Wholesale & retail | 2025 |
| Arden Automated Access Ltd | Manufacturing | 2003 |
| Ardmosh Solutions Limited | Professional & scientific | 2017 |
| Ardvarna Investment Management Limited | Professional & scientific | 2016 |
| Area Pest Control UK Ltd | Administrative & support | 2010 |
| Area Wide Limited | Real estate | 2026 |
| Arena Supreme Ltd | Hospitality | 2019 |
| Aresium Consulting Limited | Professional & scientific | 2025 |
| Argautomation Ltd | Professional & scientific | 2024 |
| Argon Automotive Group Ltd | Wholesale & retail | 2021 |
| Argon Developments Ltd | Real estate | 2025 |
| Argonaut International Limited | Professional & scientific | 2020 |
| Arial Solutions Limited | Professional & scientific | 2024 |
| Ariane Jones Limited | Health & social care | 2013 |
| Aries Skye Ltd | Professional & scientific | 2024 |
| Arif Esmail & Co Limited | Wholesale & retail | 1999 |
| Arihant Sales Limited | Wholesale & retail | 2013 |
| Arion Services Ltd | Administrative & support | 2023 |
| Arish Retail Ltd | Wholesale & retail | 2026 |
| Aristocrat Dine Ltd | Hospitality | 2020 |
| Ariva Consultancy Limited | Mining & quarrying | 2017 |
| Arjan Constructions (UK) Limited | Construction | 2017 |
| Arjanvailly Ltd | Real estate | 2026 |
| Arjath Ltd | Health & social care | 2022 |
| ARK CLS Limited | Information & communication | 1988 |
| ARK Earth Limited | Information & communication | 2010 |
| ARK Farm Limited | Education | 2012 |
| ARK Fibre Optics Limited | Information & communication | 2013 |
| ARK Roofing Limited | Construction | 2016 |
| Arkadiusz Stefaniak Ltd | Wholesale & retail | 2018 |
| Arko Surveillance and Security Ltd | Information & communication | 2025 |
| Arla Investments Ltd | Real estate | 2019 |