| Allen Archaeology Limited | Construction | 2009 |
| Allen Signs Limited | Manufacturing | 1979 |
| Allenby Construction Ltd | Construction | 2026 |
| Allenby Glass Limited | Manufacturing | 1997 |
| Allenby Training Services Limited | Education | 1999 |
| Allenby Vehicle Sales Ltd | Wholesale & retail | 2018 |
| Allenby Vehicle Services Ltd | Wholesale & retail | 2017 |
| Allencompassing Ltd | Manufacturing | 2025 |
| Allens Antiques Limited | Extraterritorial | 1976 |
| Allens Corporate Estates Ltd | Real estate | 2017 |
| Allerlon Limited | Health & social care | 2019 |
| Allhear Ltd | Wholesale & retail | 2010 |
| Alliance Recycling (UK) Ltd | Water & waste | 2015 |
| Allied EMC Limited | Professional & scientific | 2024 |
| Allied Medical Group Ltd | Health & social care | 2022 |
| Allium & Brassica Agronomy Limited | Extraterritorial | 2005 |
| Allpro Flooring Projects Ltd | Construction | 2025 |
| Allsportsuk Ltd | Other services | 2023 |
| Allsworth Rare Books Limited | Wholesale & retail | 2002 |
| Almec Plumbing & Heating Limited | Construction | 2025 |
| Almond Financial Ltd | Financial services | 2016 |
| Almond Financial Property Holdings Ltd | Real estate | 2025 |
| Alooda Limited | Manufacturing | 2005 |
| Alora Therapy Limited | Other services | 2023 |
| Alpet Associates Limited | Other services | 2012 |
| Alpha Branding Ltd | Professional & scientific | 2023 |
| Alpha Concrete Ltd | Manufacturing | 2022 |
| Alpha Paving and Groundworks Ltd | Construction | 2020 |
| Alphacom Limited | Information & communication | 2022 |
| Alpine Joinery & Restoration Ltd | Construction | 2013 |
| ALS Cargo Limited | Transport & logistics | 2018 |
| ALS Landscaping Ltd | Administrative & support | 2021 |
| ALS Lincoln Plant Hire Ltd | Administrative & support | 2026 |
| ALS Property Group Ltd | Real estate | 2023 |
| Alt-Ed Lincs Ltd | Education | 2023 |
| Alternative Commercial Finance Limited | Financial services | 2013 |
| Alternative Educational Support Services Ltd | Education | 2019 |
| Alterumcras Limited | Education | 2023 |
| Altric Limited | Manufacturing | 1985 |
| Altsani Couriers Limited | Transport & logistics | 2026 |
| Aluminium Fabricators Limited | Manufacturing | 2025 |
| AM Communications Limited | Professional & scientific | 2022 |
| AM Homebuild Ltd | Construction | 2018 |
| AM Scaffold Solutions Ltd | Construction | 2023 |
| AMA Electrical Ltd. | Energy | 2011 |
| AMA Surgical Specialists Limited | Health & social care | 2010 |
| Amalapalace Limited | Hospitality | 2025 |
| Amaldar Consulting Limited | Real estate | 2013 |
| Aman Shield Ltd | Administrative & support | 2025 |
| Amanah Property Ventures Ltd | Real estate | 2024 |
| Amanda and Partners Limited | Health & social care | 2024 |
| Amanda Coleman Jewellery Limited | Wholesale & retail | 2014 |
| Amata Limited | Wholesale & retail | 2024 |
| AMB Properties Lincoln Ltd | Real estate | 2022 |
| Ambary Spirits Ltd | Manufacturing | 2018 |
| Ambassador Homecare Limited | Health & social care | 2011 |
| Ambassadors for Health Ltd | Health & social care | 2019 |
| Ambel Accountancy Services Ltd | Professional & scientific | 2021 |
| Amber Care (Lincolnshire) Limited | Health & social care | 2013 |
| Amber Dune Ltd | Health & social care | 2023 |
| Amber Fire Protection Limited | Real estate | 1998 |
| Amber Planning Ltd | Professional & scientific | 2010 |
| Amberfire Limited | Construction | 2014 |
| Ambrooke Steel Services Limited | Manufacturing | 2009 |
| Ambrose Court Nettleham Residents Management Co Limited | Households | 2013 |
| Ambsan Ltd | Wholesale & retail | 2020 |
| Ambucopter Trading Company Limited | Wholesale & retail | 1994 |
| Amco 2013 LLP | | 2013 |
| Ameever Properties Limited | Real estate | 2018 |
| Amelia Alice Ltd | Wholesale & retail | 2025 |
| Amelio Consulting Limited | Professional & scientific | 2004 |
| Amelio Investments Limited | Financial services | 2024 |
| AMENITIES4YOU Ltd | Wholesale & retail | 2025 |
| Amethyst Health Screening Limited | Health & social care | 2011 |
| AMG Plumbing & Heating Limited | Construction | 2009 |
| AMG Property Services Lincoln Ltd | Real estate | 2024 |
| Amica HR Limited | Administrative & support | 2012 |
| Amicus (FM) Services Ltd | Agriculture & fishing | 2019 |
| Amma Helping Hands Ltd | Health & social care | 2020 |
| Ammo-Box CIC | Health & social care | 2023 |
| Ampal Ltd | Wholesale & retail | 2024 |
| Ampco 118 Limited | Professional & scientific | 2018 |
| Amper World Limited | Wholesale & retail | 2025 |
| Amplify Marketing Solutions Limited | Professional & scientific | 2022 |
| Ampower Ltd | Administrative & support | 2015 |
| AMR Catering HAY on WYE Limited | Hospitality | 2025 |
| AMR Paving & Landscaping Ltd | Construction | 2024 |
| AMS Build Group Ltd | Financial services | 2022 |
| AMS Build Ltd | Wholesale & retail | 2015 |
| AMS Concrete Ltd | Manufacturing | 2025 |
| AMS Signs Ltd | Professional & scientific | 2022 |
| AMS Technology Solutions Limited | Other services | 2013 |
| AMT Service Ltd | Transport & logistics | 2023 |
| Amuh Consultancy Limited | Professional & scientific | 2026 |
| AMY Hepton Design Limited | Professional & scientific | 2016 |
| AMZ Trend Ltd | Manufacturing | 2017 |
| Anaergia Limited | Administrative & support | 2008 |
| Analoglocums Ltd | Health & social care | 2024 |
| Ancaster Professional Services Limited | Professional & scientific | 2012 |
| Anchor Studios Ltd | Information & communication | 2015 |