| Arlec Electrical Company Limited | Wholesale & retail | 2016 |
| Arlec UK Holdings Limited | Extraterritorial | 1996 |
| Armada Boat Hire Ltd | Transport & logistics | 2009 |
| Armada Waterside Limited | Manufacturing | 2011 |
| Army Glamping Ltd | Hospitality | 2022 |
| Arnoldarmsbarby Limited | Hospitality | 2025 |
| ARO Spedition Limited | Transport & logistics | 2021 |
| Arpy Jayarre Limited | Real estate | 2022 |
| Arrec Investment Limited | Financial services | 2020 |
| Arrive Wellness Ltd | Information & communication | 2025 |
| Arrk Services Ltd | Real estate | 2006 |
| Arrowdown Limited | Construction | 2000 |
| Arsh Innovative IT Ltd | Information & communication | 2017 |
| Arshan Housing Private Ltd | Real estate | 2021 |
| Art Electronics Ltd | Other services | 2023 |
| Artcube International Limited | Construction | 2020 |
| Arth Estate Limited | Real estate | 2022 |
| Artifex Galleries LLP | | 2010 |
| Artificial Grass Warwickshire Ltd | Administrative & support | 2013 |
| Artiglio Limited | Construction | 2015 |
| Artiling Ltd | Construction | 2022 |
| Artisan Shutters Limited | Manufacturing | 2026 |
| Artur Jaworski Transport Limited | Transport & logistics | 2006 |
| Arturn Ltd | Manufacturing | 2017 |
| Artvik Limited | Professional & scientific | 2021 |
| Arul Limited | Wholesale & retail | 2015 |
| Arya Consult Ltd | Wholesale & retail | 2024 |
| Aryanvi Ltd | Real estate | 2024 |
| Aryanvi Tech Limited | Information & communication | 2025 |
| AS Advanced Skin Care Academy Ltd | Education | 2021 |
| AS Advanced Skin Care Ltd | Other services | 2015 |
| AS DEO Properties Limited | Real estate | 2026 |
| AS UK Dental Services Limited | Health & social care | 2016 |
| AS UK Property Services Limited | Administrative & support | 2017 |
| Asap 4 YOU Limited | Transport & logistics | 2025 |
| Ascend Transformation Ltd | Information & communication | 2023 |
| ASD Johnsons Limited | Real estate | 2023 |
| ASH Park Group Limited | Manufacturing | 2006 |
| Ashby Developments (Cornmarket) Limited | Real estate | 2025 |
| Ashimamura Couriers Ltd | Transport & logistics | 2026 |
| Ashlawn Builders Limited | Construction | 2001 |
| Ashlawn Investments Limited | Financial services | 2020 |
| Ashlawn Management Limited | Construction | 2024 |
| Ashlies Rise Project Solutions Limited | Wholesale & retail | 2024 |
| Ashlies Rise Property and Management Limited | Real estate | 2024 |
| Ashri & Ashir Ltd | Real estate | 2025 |
| Ashton Lodge Hotel Limited | Hospitality | 2011 |
| ASHTREE1 Ltd | Construction | 2022 |
| ASJ Advisory Ltd | Information & communication | 2023 |
| ASK Dave Ltd | Information & communication | 2020 |
| ASK Property Investments Midlands Limited | Real estate | 2016 |
| ASK UK Holdings Limited | Construction | 2017 |
| Asolt Limited | Wholesale & retail | 2019 |
| Aspect Development Group Ltd | Construction | 2026 |
| Aspicedo Ltd | Professional & scientific | 2022 |
| Aspiration Europe Limited | Professional & scientific | 2004 |
| Asplin Solutions Ltd | Information & communication | 2020 |
| Assad Transport Limited | Transport & logistics | 2018 |
| Asset Survey Solutions Group UK Ltd | Professional & scientific | 2025 |
| Assilium Limited | Information & communication | 2020 |
| Assure Fire Door Inspections Limited | Professional & scientific | 2023 |
| Assured Advice Ltd | Professional & scientific | 2018 |
| AST Rugby Limited | Education | 2017 |
| Asterids Solutions Limited | Information & communication | 2024 |
| Astonishing Prop Maintenance Limited | Construction | 2017 |
| Astrazilla Ltd | Arts & recreation | 2021 |
| Astrum HR Search & Selection Limited | Other services | 2008 |
| Asvt Ltd | Transport & logistics | 2023 |
| ASW Vending Services Ltd | Hospitality | 2008 |
| Asys Technologies Limited | Information & communication | 2021 |
| AT Transport (Rugby) Ltd | Transport & logistics | 2022 |
| Atas Groceries Ltd | Wholesale & retail | 2026 |
| ATB Limited | Transport & logistics | 2009 |
| ATELIER512 Ltd | Professional & scientific | 2024 |
| Atharva Properties Ltd | Real estate | 2026 |
| Atis Fragrances Ltd | Wholesale & retail | 2024 |
| ATK Arboriculture Ltd | Agriculture & fishing | 2018 |
| Atlas Boat Sales Ltd | Wholesale & retail | 2025 |
| Atlas Engineering Services Limited | Professional & scientific | 2026 |
| Atlas Wanderers Travel Ltd | Arts & recreation | 2025 |
| Atlasaccess Ltd | Construction | 2024 |
| Atomic Trading Co. Limited | Hospitality | 2011 |
| Atransit Limited | Transport & logistics | 2015 |
| Atrium Logistics Limited | Transport & logistics | 2026 |
| Atsys.Tech Limited | Information & communication | 2021 |
| Atterton and Ellis Holdings Limited | Financial services | 2023 |
| Attingham Consulting Engineers Limited | Professional & scientific | 2009 |
| Attire Aangan Ltd | Wholesale & retail | 2024 |
| Audiobiz Pro Limited | Wholesale & retail | 2017 |
| Aumbit Ltd | Information & communication | 2025 |
| Auntie Lolo's Kitchen Ltd | Hospitality | 2026 |
| Aura Farm Media Group Ltd | Information & communication | 2025 |
| Aura Property Development Limited | Real estate | 2008 |
| Aurum SS Limited | Professional & scientific | 2024 |
| Austdec Ltd | Construction | 2021 |
| Austin Roofing Services Trading Ltd | Construction | 2023 |
| Austin Seven Spares Limited | Wholesale & retail | 2011 |
| Autins Group PLC | Professional & scientific | 2014 |
| Autins Limited | Manufacturing | 1966 |
| Autins Technical Centre Limited | Professional & scientific | 2002 |