| ASH Wellness & Performance Ltd | Health & social care | 2017 |
| Ashby Gifts Ltd | Wholesale & retail | 2018 |
| Ashcroft MEP Consulting Ltd | Professional & scientific | 2025 |
| Ashcroft Plastering Ltd | Construction | 2017 |
| Ashleigh Management Company (Lincoln) Limited | Real estate | 2013 |
| Ashley Stockbridge Brickwork Ltd | Construction | 2019 |
| Ashley's Transport Services Ltd | Transport & logistics | 2024 |
| Ashlin Farm Barns Ltd | Hospitality | 2018 |
| Ashover Estates Limited | Agriculture & fishing | 1999 |
| ASJ Fitness Club Limited | Arts & recreation | 2026 |
| Askam Conti Holdings Limited | Financial services | 2018 |
| Aslam Oncology Ltd | Health & social care | 2021 |
| ASM Architecture Ltd | Professional & scientific | 2019 |
| ASP Construction Lincoln Ltd | Construction | 2016 |
| ASP Glazing Limited | Manufacturing | 2001 |
| Aspects of Beauty Ltd | Other services | 2002 |
| Aspire Day Service Limited | Health & social care | 2019 |
| Aspire Management Consultancy Limited | Professional & scientific | 2012 |
| Aspire Mortgages (Sleaford) Limited | Financial services | 2018 |
| ASQ Clinical Services Ltd | Health & social care | 2026 |
| Asset Plus Digital Limited | Information & communication | 2025 |
| Assign Safety Solutions Ltd | Administrative & support | 2018 |
| Association of Electricity Supply Pensioners Limited | Other services | 1996 |
| Assuage Healthcare Ltd | Public administration | 2020 |
| Assured Edge Ltd | Professional & scientific | 2026 |
| Assuria Holding Ltd | Real estate | 2023 |
| Astar (Advisory & Business Services) Limited | Professional & scientific | 2011 |
| Astar Innovations Limited | Financial services | 2026 |
| Astemarc Ltd | Professional & scientific | 2024 |
| Asterius Technologies Limited | Information & communication | 2021 |
| Asterius Technology Limited | Information & communication | 2021 |
| Asterix Properties Ltd | Real estate | 2019 |
| Aston Construction Ltd | Construction | 2007 |
| Aston Consult Ltd | Professional & scientific | 2019 |
| Aston Hopkins Ltd | Professional & scientific | 2010 |
| Astra Consults Ltd | Health & social care | 2022 |
| Astrava Living Ltd | Real estate | 2025 |
| Astria Payroll Limited | Professional & scientific | 2002 |
| AT Building Lincolnshire Ltd | Construction | 2022 |
| AT Event Services Ltd | Administrative & support | 2006 |
| AT Strategic Consulting Limited | Professional & scientific | 2025 |
| Ataberk Car Ltd | Transport & logistics | 2025 |
| Atac UK Ltd | Professional & scientific | 2009 |
| Atacuk Manufacturing Ltd | Manufacturing | 2011 |
| Atalanti Five Limited | Administrative & support | 2005 |
| Atelier Voyria Ltd | Professional & scientific | 2024 |
| Atherstone Holdings Limited | Professional & scientific | 2020 |
| Athlyq Ltd | Information & communication | 2026 |
| ATI Motors Ltd | Wholesale & retail | 2018 |
| Atkins & Atkins Ltd | Professional & scientific | 2014 |
| Atkins & Partners Limited | Information & communication | 2024 |
| Atkinson Saul Fairholm Limited | Professional & scientific | 2002 |
| Atlantic Horizon Ltd | Financial services | 2025 |
| Atlas Kebab Limited | Hospitality | 2025 |
| Atlas Scaffolding and Access Limited | Construction | 2021 |
| Atlas Scaffolding Group Limited | Construction | 2021 |
| Atomic Dermatology Limited | Health & social care | 2022 |
| Attar Ltd | Wholesale & retail | 2017 |
| Attie Homes Ltd | Real estate | 2019 |
| Attractive Limited | Real estate | 2004 |
| Attribute Sports Ltd | Wholesale & retail | 2024 |
| Attwell Properties Ltd | Real estate | 2026 |
| Auber's Ridge Management Company Limited | Households | 2019 |
| Aubourn Architecture Limited | Professional & scientific | 2020 |
| Auctus AI Automations Ltd | Information & communication | 2025 |
| Audio Platform Ltd | Wholesale & retail | 2015 |
| Augustine John Developments Ltd | Real estate | 2012 |
| Aura Lake Ltd | Wholesale & retail | 2022 |
| Aura Rents Ltd | Real estate | 2025 |
| Aura-Soma Limited | Wholesale & retail | 1994 |
| Auraya Group Ltd | Administrative & support | 2010 |
| Auraya.Bet Ltd | Real estate | 2018 |
| Auraya.Block Ltd | Information & communication | 2022 |
| Auraya.Wallet Ltd | Financial services | 2020 |
| Aurora Rides Ltd | Transport & logistics | 2023 |
| Aurum Academies Trust | Education | 2012 |
| Aurum Insights Ltd | Professional & scientific | 2024 |
| Aurvex Ltd | Wholesale & retail | 2026 |
| Austin T Ltd | Arts & recreation | 2025 |
| Austin William Ltd | Real estate | 2022 |
| Authentic Asia Ltd | Hospitality | 2024 |
| Authentic Comms Strategic Consultancy Limited | Professional & scientific | 2020 |
| Authentic Global Ltd | Health & social care | 2025 |
| Auto Archi Ltd | Information & communication | 2025 |
| Auto Exhaust & Tyres Ltd | Wholesale & retail | 2002 |
| Auto-Mate(Uk) Ltd | Wholesale & retail | 2011 |
| Autonary AI Ltd | Professional & scientific | 2025 |
| Autoplazaa Ltd | Wholesale & retail | 2024 |
| AUTOSTAR2000 Limited | Wholesale & retail | 2013 |
| Autrix Limited | Manufacturing | 2023 |
| AV Lincoln Limited | Real estate | 2013 |
| AVA Clear Solutions Limited | Construction | 2026 |
| AVA Health Life Ltd | Health & social care | 2022 |
| Avanti Residential Ltd | Real estate | 2026 |
| Avanti Restaurants Ltd | Hospitality | 2019 |
| Avari Wireless Limited | Information & communication | 2021 |
| Aventustattoo Ltd | Arts & recreation | 2022 |
| Avinmin Ltd | Wholesale & retail | 2020 |
| Avlee Law Limited | Other services | 2014 |
| Avocado Labs Limited | Information & communication | 2011 |