| Arami Consulting Ltd | Health & social care | 2022 |
| ARB Building & Property Services Ltd | Construction | 2026 |
| ARC Aero Limited | Professional & scientific | 2024 |
| ARC Business Services Ltd | Professional & scientific | 2003 |
| Arcmates Construction Services Limited | Construction | 2016 |
| Arcmates Projects Ltd | Construction | 2020 |
| Argon Lyle Limited | Professional & scientific | 2021 |
| Argonaut Advisory Ltd | Administrative & support | 2023 |
| Argus Properties Ltd | Construction | 2019 |
| Arion Embroidery and Print Ltd | Manufacturing | 2021 |
| Arion Shop Ltd | Extraterritorial | 2024 |
| Arion Trading Limited | Wholesale & retail | 2013 |
| Arion Training & Development Ltd | Professional & scientific | 2006 |
| Arisingtide Ltd | Professional & scientific | 2021 |
| Arkhitekton Group Ltd | Construction | 2024 |
| Arlo Engineering Limited | Manufacturing | 2013 |
| Arnolds Quick Dried Foods Limited | Manufacturing | 1976 |
| Arora Phone Xperts Ltd | Wholesale & retail | 2026 |
| Aros Store Limited | Wholesale & retail | 2025 |
| ASH Sawyer Psychic Medium Ltd | Other services | 2022 |
| Asher Close (Helpringham) Management Company Limited | Households | 2024 |
| ASK SAM Mortgages Ltd | Financial services | 2025 |
| Aspire Free House Ltd | Hospitality | 2013 |
| Aspire Learning Hub Ltd | Education | 2024 |
| Associate Computer Services Limited | Information & communication | 1997 |
| Asteria Legal Services Limited | Information & communication | 2025 |
| Astor & Green Ltd | Manufacturing | 2025 |
| Aswarby Old Rectory Limited | Extraterritorial | 1993 |
| Athfluence Limited | Professional & scientific | 2025 |
| Atlas Housing Limited | Construction | 2019 |
| Attwood's Testing Solutions Ltd | Professional & scientific | 2026 |
| Aurora Training and Security Solutions Ltd | Administrative & support | 2025 |
| Austin Clayton Historic Limited | Wholesale & retail | 2015 |
| Autronus Ltd | Information & communication | 2021 |
| Aveland Consultancy and Training Ltd | Information & communication | 2023 |
| Aveland Electrical Limited | Construction | 2001 |
| Aveland Pest Solutions Limited | Agriculture & fishing | 2010 |
| Aveland Properties Limited | Real estate | 2021 |
| AWA Developments Limited | Real estate | 2001 |
| AWH Construction Limited | Construction | 2023 |
| Axe&Wood Ltd | Manufacturing | 2024 |
| Axis IT Solutions Ltd | Information & communication | 2022 |
| B & J Mann Properties Limited | Real estate | 1992 |
| B C Agri Services Ltd | Manufacturing | 2022 |
| B J Karan Brothers Limited | Wholesale & retail | 2020 |
| B K Property Services Ltd | Construction | 2022 |
| B Mcintyre Property Ltd | Households | 2024 |
| B Pope & Sons Limited | Construction | 1993 |
| B.S.J. Holdings Limited | Transport & logistics | 1993 |
| B3H Ltd | Financial services | 2026 |
| BA Offshore Solutions Ltd | Professional & scientific | 2025 |
| Bahoz Catering Ltd | Hospitality | 2024 |
| Bailey Chessum Developments Limited | Real estate | 2007 |
| Bailey Trailers Limited | Manufacturing | 1986 |
| Baker Plant Hire (Sleaford) Limited | Administrative & support | 2012 |
| Baker Plant Sales Ltd | Wholesale & retail | 2025 |
| Baker Training Ltd | Education | 2023 |
| Bakersrest Limited | Professional & scientific | 2023 |
| Bakewell Road High-Tech Management Company Limited | Real estate | 1985 |
| Banovallum Properties Limited | Construction | 2011 |
| Baodan Sleaford Limited | Hospitality | 2023 |
| Barbers Chop and Bar Ltd | Hospitality | 2025 |
| Barka P&D UK Ltd | Manufacturing | 2023 |
| Barney & MAX Ltd | Wholesale & retail | 2026 |
| Barns Properties Ltd | Real estate | 2025 |
| Barstows Ltd | Manufacturing | 2026 |
| Barworth Agriculture Ltd | Agriculture & fishing | 2008 |
| Barworth Research Limited | Agriculture & fishing | 2018 |
| Bass View Consulting Limited | Professional & scientific | 2020 |
| Bateman FOX Limited | Administrative & support | 2009 |
| BBA Property Management Ltd | Real estate | 2019 |
| BE Sustainable Placemaking Limited | Extraterritorial | 2024 |
| Beacon Hill Property Group Ltd | Households | 2025 |
| Beaumont Court Management Ltd | Households | 2013 |
| Behaviour Wise Ltd | Education | 2013 |
| BEL Holdings Ltd | Real estate | 2024 |
| Bells Angels Limited | Administrative & support | 2014 |
| Bemand Properties Limited | Real estate | 2005 |
| BEN COY Farrier Limited | Agriculture & fishing | 2021 |
| Benfield Engineering Ltd | Manufacturing | 2026 |
| Bernard Holmes Precision Limited | Manufacturing | 1960 |
| Bespoke Hearing Services Limited | Health & social care | 2020 |
| Bespoke Mortgage and Protection Solutions Ltd | Administrative & support | 2015 |
| Best Pain Management Ltd | Health & social care | 2014 |
| Bewell Bezero Bidco Limited | Financial services | 2026 |
| Bewell Bezero Limited | Extraterritorial | 2024 |
| Bewell Bezero Midco Limited | Financial services | 2026 |
| Bewell Bezero Topco Limited | Financial services | 2026 |
| Bextay Limited | Transport & logistics | 2023 |
| BFF Group Ltd | Agriculture & fishing | 2023 |
| BG Power Services Ltd | Administrative & support | 2007 |
| Bgtf Limited | Professional & scientific | 2002 |
| Big Skies Brewing Company Ltd | Manufacturing | 2025 |
| Billingborough Cars and Commercials Limited | Wholesale & retail | 2008 |
| Billingborough Self Store Limited | Transport & logistics | 2025 |
| Biodiamond Consulting Ltd | Administrative & support | 2020 |
| Bitsnbobs the 3D Print Shop Ltd | Wholesale & retail | 2025 |
| BJB Buildings Ltd | Real estate | 2026 |
| Bkmw Ltd | Real estate | 1998 |
| Black Bull Rusko Ltd | Hospitality | 2025 |