| Architectural Design Yorkshire Limited | Professional & scientific | 2017 |
| ARCHIVEPEU205 Limited | Administrative & support | 2021 |
| Arden House Investments Limited | Real estate | 1959 |
| Ardiess Limited | Manufacturing | 2002 |
| Aredeef Ltd | Professional & scientific | 2023 |
| Areion Academy Limited | Education | 2021 |
| Arena Health & Fitness UK Ltd | Administrative & support | 2016 |
| Argen Engineering Ltd | Construction | 2024 |
| Argyle Design Collective Limited | Wholesale & retail | 2026 |
| Aristar Consulting Group Ltd | Wholesale & retail | 2018 |
| Ariya Cosmos Ltd | Information & communication | 2024 |
| Arkwood Developments Limited | Construction | 2018 |
| Arlington Farming Limited | Agriculture & fishing | 1998 |
| Arran Rise Residents Management Company Limited | Households | 2013 |
| Art Demolition Ltd | Construction | 2013 |
| Art Support Limited | Administrative & support | 2019 |
| Artenis Limited | Professional & scientific | 2008 |
| Artistic Iron Products Limited | Manufacturing | 2003 |
| Asana Ltd | Health & social care | 2026 |
| Ascent Safety Consultants Ltd | Professional & scientific | 2014 |
| ASH Homes (Lincoln) Ltd | Construction | 2018 |
| Ash's Vinylfixx Limited | Wholesale & retail | 2026 |
| Asha Restaurant (Newark) Ltd | Hospitality | 2013 |
| Ashcroft & Vale Limited | Extraterritorial | 2026 |
| Ashcroft Rose Ltd | Real estate | 2023 |
| Ashfield Farmed Environment Services Ltd | Agriculture & fishing | 2011 |
| ASK People Ltd | Administrative & support | 2026 |
| Aspen Assets Limited | Financial services | 2007 |
| Aspira Aerial Applications Limited | Professional & scientific | 2015 |
| Aspley Renewables Ltd | Construction | 2026 |
| Asquith Manners Limited | Professional & scientific | 2019 |
| Assured Education Ltd | Education | 2015 |
| AST Equity Limited | Real estate | 2022 |
| Astle's Electrical Solutions Limited | Construction | 2019 |
| Astley Rathbone Farming Ltd | Agriculture & fishing | 2020 |
| Astro Drone Shows Ltd | Arts & recreation | 2026 |
| AT the Nest Limited | Health & social care | 2025 |
| Atered Limited | Real estate | 1982 |
| ATH Cars Limited | Wholesale & retail | 2023 |
| Atkin Shopfitting Design Limited | Professional & scientific | 2012 |
| Atlas Advanced Internet Solutions Limited | Extraterritorial | 2003 |
| Atlas Rose Ltd | Construction | 2021 |
| ATM 64 Limited | Manufacturing | 1999 |
| ATM 74 Limited | Transport & logistics | 1998 |
| Atom Mobile Ltd | Extraterritorial | 2016 |
| Attention to Detail (Fabrications) Limited | Manufacturing | 2020 |
| Aubourn Timber Ltd | Wholesale & retail | 2018 |
| Aunt Sally Animal Nanny Ltd | Professional & scientific | 2015 |
| Auor Limited | Construction | 2016 |
| Aura Journeys (Group) Limited | Financial services | 2021 |
| Aura Journeys Ltd | Transport & logistics | 2014 |
| Aura Journeys Network Limited | Professional & scientific | 2017 |
| Aura Sports Therapy & Wellness Limited | Administrative & support | 2026 |
| Auto and Part Worn Tyres Limited | Wholesale & retail | 2014 |
| Auto Bling Ltd | Wholesale & retail | 2024 |
| Auto REN Ltd | Wholesale & retail | 2026 |
| Auto Smart Check Ltd | Wholesale & retail | 2023 |
| AUTOM8 IT Limited | Information & communication | 2015 |
| Autumn Ambitions Ltd | Wholesale & retail | 2019 |
| Autumn Ambitions Properties Ltd | Real estate | 2024 |
| Avcal Consultants Ltd. | Information & communication | 2017 |
| AVF Diagnostics Ltd | Wholesale & retail | 2017 |
| Aviation Roofing Ltd | Construction | 2021 |
| Avis Indie Art Limited | Arts & recreation | 2011 |
| Avit Motorsport Limited | Wholesale & retail | 2021 |
| Avocado Web Development Limited | Information & communication | 2012 |
| Avoncross Limited | Construction | 1999 |
| Avossi Limited | Real estate | 2023 |
| AWE Newtech Limited | Manufacturing | 2000 |
| AWM Tools Limited | Manufacturing | 2021 |
| AWR Holdings (Midlands) Ltd | Financial services | 2024 |
| Axio GAS Ltd | Construction | 2021 |
| Axispro Safety Ltd | Education | 2024 |
| Aylaa Ltd | Hospitality | 2024 |
| Ayrshire House Limited | Health & social care | 2019 |
| B & H Construction (Newark) Limited | Construction | 1999 |
| B & MC Lighting Limited | Construction | 2006 |
| B & S Hollingworth & SON Limited | Transport & logistics | 2004 |
| B Ward Electrical Contractors Limited | Construction | 2009 |
| B&C Future Developments Ltd | Professional & scientific | 2018 |
| B. M. & M. J. Reed Ltd | Real estate | 2023 |
| B. N. Gibson Limited | Transport & logistics | 1978 |
| B.Fearn(Ollerton)Limited | Administrative & support | 1941 |
| B.N Gibson Holdings Limited | Financial services | 2017 |
| B/5 Group Ltd | Wholesale & retail | 2024 |
| BAA Baby Ltd | Manufacturing | 2018 |
| Babataku PVT Ltd | Information & communication | 2012 |
| Back to Life Health Ltd | Health & social care | 2015 |
| BAD Apple Cider Limited | Manufacturing | 2015 |
| Badge Media Limited | Professional & scientific | 2002 |
| Baditech Engineering and Consultancy Ltd | Wholesale & retail | 2019 |
| Bailey Developments (Notts) Ltd | Construction | 2025 |
| Bainbridge Clothiers Limited | Wholesale & retail | 2024 |
| Bainbridge Court Management Co Ltd | Households | 2019 |
| BAK2BOX Ltd | Construction | 2012 |
| Bala and Meena Ltd | Real estate | 2026 |
| Balanced Academy Ltd | Professional & scientific | 2023 |
| Balby Power Limited | Extraterritorial | 2016 |
| Balderton Express Ltd | Wholesale & retail | 2020 |
| Balderton Tile Centre Limited | Wholesale & retail | 2010 |