| Ambit Stainless Limited | Manufacturing | 2001 |
| Amplified Productions Ltd | Arts & recreation | 2022 |
| AND Marine Ltd. | Professional & scientific | 2006 |
| Andrej Commerce Ltd | Wholesale & retail | 2021 |
| Andrew Goldson Heating & GAS Services Ltd | Construction | 2003 |
| Andrew Hunt Ltd | Administrative & support | 2023 |
| Andrew Sime & Company Limited | Arts & recreation | 1985 |
| Andrew Smith Furniture Limited | Administrative & support | 2003 |
| Angela Scott Properties Limited | Real estate | 2022 |
| Angelica CARE24 Ltd | Health & social care | 2019 |
| Angelus Transport Ltd | Transport & logistics | 2024 |
| Anglia Catering Services Limited | Hospitality | 2003 |
| Anglia Door Services Limited | Other services | 2000 |
| Anglia Locksmiths & Safe Engineers Limited | Manufacturing | 1977 |
| Anglia Weld Testing Limited | Manufacturing | 2003 |
| Anglian Storage Limited | Administrative & support | 2006 |
| Anglofox Limited | Wholesale & retail | 1984 |
| ANI M Holdings Ltd | Financial services | 2024 |
| Anyways Freight Limited | | 1981 |
| Anzinc Co., Ltd | Extraterritorial | 2013 |
| Aorist Limited | Real estate | 1979 |
| Apidly Ltd | Information & communication | 2026 |
| Appified Labs Ltd | Information & communication | 2019 |
| Aqua-Heat Envirotech Ltd | Construction | 2006 |
| Aquarian Contracts Limited | Construction | 2007 |
| Aramat Limited | Professional & scientific | 1999 |
| ARC Global Engineering Limited | Information & communication | 2022 |
| Ardex UK Limited | Manufacturing | 1960 |
| Ardmore Veterinary Group Limited | Professional & scientific | 2006 |
| Arista Corporation Limited | Extraterritorial | 1999 |
| Arizent Limited | Arts & recreation | 2007 |
| Aromco Limited | Manufacturing | 1985 |
| Arpl Living Ltd | Real estate | 2020 |
| Arrow Boats Limited | Other services | 1972 |
| Arthur Wilson Digital Marketing Ltd | Professional & scientific | 2024 |
| Artofboog Ltd | Professional & scientific | 2026 |
| As&Co Ltd | Real estate | 2024 |
| ASH Nelson Limited | Water & waste | 2003 |
| Ashluxe Ltd | Wholesale & retail | 2024 |
| Aslanrodi Limited | Real estate | 2016 |
| Aspall Cyder Limited | Wholesale & retail | 1986 |
| Aspall Holdings Limited | Financial services | 2015 |
| Aspects Health & Beauty Clinic Limited | Other services | 2002 |
| Associated Designs (UK) Limited | Information & communication | 2002 |
| Asus Logistics Ltd | Transport & logistics | 2018 |
| ASZ Holdings Ltd | Information & communication | 2023 |
| Athena Picture Agency Zing Limited | Professional & scientific | 2023 |
| Atlantis Water Treatment Limited | Manufacturing | 1999 |
| Atlas Arts Housing Limited | Wholesale & retail | 1983 |
| AUDACITY2LEAD Limited | Information & communication | 2022 |
| Audimus Limited | Information & communication | 2022 |
| Auglass Limited | Extraterritorial | 2002 |
| Aura Brand Solutions Limited | Manufacturing | 1994 |
| Aura Graphics Limited | Professional & scientific | 1997 |
| Aura Indigo Ltd | Wholesale & retail | 2024 |
| Austin Handling Ltd | Manufacturing | 1985 |
| Austin Installations Electrical Contractors Limited | Construction | 2006 |
| Autovision Car Sales (Lowestoft) Limited | Professional & scientific | 2017 |
| Avalance Limited | Information & communication | 2013 |
| Avantus Marketing Services UK Limited | Agriculture & fishing | 2023 |
| Aveston UK Limited | Wholesale & retail | 2023 |
| Avid Mechanical Services Ltd | Construction | 2007 |
| Awkun Ltd | Information & communication | 2004 |
| Axod Media Limited | Information & communication | 2006 |
| AYM Consulting Ltd | Health & social care | 2025 |
| Azara Media Limited | Professional & scientific | 2008 |
| Azead Trading and Contracting Company Limited | Agriculture & fishing | 2025 |
| B & W Properties (Newmarket) Limited | Real estate | 1981 |
| B Blöhm Ltd | Real estate | 2019 |
| B&H Solutions Ltd | Professional & scientific | 2022 |
| B.B.C. Contracts Limited | | 1987 |
| B.C. Tube Benders Limited | Manufacturing | 1979 |
| B.M.R. Limited | Administrative & support | 1998 |
| Babacamper Limited | Administrative & support | 2025 |
| Baby Swimming Norfolk LLP | | 2020 |
| Bagnols | Information & communication | 2017 |
| Bamboo Homes and Developments Ltd | Construction | 2018 |
| Bamcrest Ltd | Real estate | 2025 |
| Barham Hall Farm Limited | Real estate | 1995 |
| Barnett Companies Limited | Professional & scientific | 2024 |
| Barry Clamp & Sons Limited | Construction | 2003 |
| Barton Place Trading Company Ltd. | Agriculture & fishing | 1998 |
| Bartrum's Road Services Limited | Transport & logistics | 1955 |
| Bartrums Haulage and Storage Limited | Transport & logistics | 1978 |
| Basaran Group Limited | Administrative & support | 2023 |
| Bavent Limited | Agriculture & fishing | 2008 |
| BBG Trading Ltd | Wholesale & retail | 2024 |
| BE Punched Ltd | Manufacturing | 2024 |
| Bears GAS Services Ltd | Energy | 2025 |
| Beauhach Properties Ltd | Real estate | 2016 |
| Becker Consultancy Services Limited | Professional & scientific | 2022 |
| Beckford Homes Ltd | Other services | 2022 |
| Beckwill Building Contractors Limited | Wholesale & retail | 2003 |
| Bedingfield Hall Farms Limited | Agriculture & fishing | 1944 |
| BEE Employed Ltd | Administrative & support | 2022 |
| Beego Express Couriers Ltd | Transport & logistics | 2022 |
| Beehive Coils Limited | Manufacturing | 1968 |
| Beeline Logic Ltd | Wholesale & retail | 2018 |
| Beeyoutiful Gifts Ltd | Wholesale & retail | 2024 |
| Belden Mexico Enterprises Limited | Manufacturing | 2018 |