| Atlantis Southend Ltd | Construction | 2019 |
| Atlo Limited | Administrative & support | 2012 |
| Atomic Design Ltd | Professional & scientific | 2012 |
| Attac Projects & Trade Management Ltd | Construction | 2025 |
| Audaz Ltd | Education | 2026 |
| Audrey Contracts Limited | Wholesale & retail | 2009 |
| Aura Mortgages Limited | Financial services | 2023 |
| Aurora Commercial Services Limited | Administrative & support | 2015 |
| Aurora Environmental Solutions Ltd | Administrative & support | 2023 |
| Aurora Merchandise Ltd | Wholesale & retail | 2014 |
| Austin Taxi Limited | Transport & logistics | 2025 |
| Authentic Island Foods Ltd | Manufacturing | 2016 |
| Auto Genesis Management Limited | Professional & scientific | 2015 |
| Auto Medics @ Vale Works Limited | Professional & scientific | 2011 |
| Auto Parabolica Limited | Wholesale & retail | 2020 |
| Auto T Services Ltd | Wholesale & retail | 2025 |
| Autocoding Ltd | Extraterritorial | 2024 |
| Autocraft (Essex) Limited | Wholesale & retail | 2020 |
| Autofabrica Limited | Manufacturing | 2011 |
| Automotive FIX Ltd | Manufacturing | 2023 |
| Autotech Vehicle Solutions Limited | Wholesale & retail | 2018 |
| AV Hand Car Wash Ltd | Administrative & support | 2025 |
| Avamore Capital Bridging Limited | Financial services | 2017 |
| Avamore Finance 1 Limited | Financial services | 2018 |
| Avant Garde Commercial Kitchen Ltd | Manufacturing | 2026 |
| Avanti Investment Concepts Limited | Professional & scientific | 2003 |
| Avcad Ltd | Professional & scientific | 2008 |
| Aventuris Management International (UK) Ltd | Financial services | 2020 |
| Avenue of Academia Ltd | Education | 2024 |
| Avera Beauty Limited | Other services | 2025 |
| Avery Fields (Birmingham) Management Company Limited | Households | 2016 |
| Avgerinos Limited | Health & social care | 2015 |
| Avisford Grange (Walberton) Management Company Limited | Households | 2019 |
| Avon Lippiatt Hobbs (Contracting) Limited | Other services | 1978 |
| Avooma Airlines (UK) Limited | Transport & logistics | 2020 |
| Avro Accountants Limited | Professional & scientific | 2025 |
| Axis 343 Southchurch Road Southend on Sea Management Limited | Households | 2005 |
| Aykley Woods (Durham) Management Company Limited | Households | 2016 |
| Ayletts House Limited | Hospitality | 2010 |
| Ayra Homes Limited | Real estate | 2023 |
| AZ JDM Cars Ltd | Wholesale & retail | 2025 |
| B & B Ballerz Ltd | Arts & recreation | 2025 |
| B & Boss Electronics Limited | Wholesale & retail | 2015 |
| B F S Trading Limited | Wholesale & retail | 2018 |
| B G Glazing Group Ltd | Construction | 2019 |
| B M Jordan Financial Solutions Ltd | Professional & scientific | 2026 |
| B Molnar Catering Ltd | Hospitality | 2018 |
| B View Ltd | Construction | 2025 |
| B W Motoring Services Ltd | Wholesale & retail | 2011 |
| B-Secure Locksmiths Ltd | Construction | 2006 |
| B.J. Davis Limited | Construction | 2016 |
| B.L. Wheatley & Co Limited | Professional & scientific | 1998 |
| B.U.S. Premier Ltd | Wholesale & retail | 2014 |
| B25 Pro Ltd | Arts & recreation | 2025 |
| B2C (Holdings) Limited | Financial services | 2010 |
| B2C Lead GEN Ltd | Professional & scientific | 2022 |
| B2R Capital Limited | Extraterritorial | 2014 |
| B2R Finance Limited | Extraterritorial | 2014 |
| BA Autotech Ltd | Wholesale & retail | 2026 |
| BAA Cost Management Ltd | Professional & scientific | 2026 |
| Back 2 Best Sports Injury and Rehabilitation Clinic Limited | Health & social care | 2014 |
| BAD BOY Promotions Limited | Administrative & support | 2010 |
| Bailey Custom Auto Trims Ltd | Manufacturing | 2022 |
| BAJ Holdings Limited | Real estate | 2018 |
| Baker Johnson & Associates Limited | Construction | 1999 |
| Bakersfield Services Ltd | Professional & scientific | 2020 |
| Balbinka Supermarket Ltd | Wholesale & retail | 2021 |
| Balia Builders Ltd | Construction | 2009 |
| Ballabon Ltd | Professional & scientific | 2021 |
| Ballincar Holdings Ltd | Financial services | 2024 |
| Balman Fitness Ltd | Arts & recreation | 2025 |
| Balmoral Court RTM Company Limited | Households | 2018 |
| Bambino Events Ltd | Arts & recreation | 2022 |
| Bammtest Limited | Professional & scientific | 2012 |
| BAN Stores Ltd | Wholesale & retail | 2026 |
| Banfield Advisory Limited | Professional & scientific | 2022 |
| Bango Spice Limited | Hospitality | 2025 |
| Bankes Contracts Limited | Construction | 1985 |
| Banwy Properties Limited | Hospitality | 2020 |
| BAP Traders Ltd | Wholesale & retail | 2026 |
| Bar Vino Limited | Hospitality | 2015 |
| Barbac Payne Wealth Management Ltd | Professional & scientific | 2017 |
| Bare-Skin Tonic Limited | Other services | 2024 |
| Bargain Cart Limited | Wholesale & retail | 2024 |
| Barkerend Property Limited | Real estate | 2018 |
| Barkers Private Hire Limited | Transport & logistics | 2021 |
| Barling Flowers Limited | Wholesale & retail | 2020 |
| Barnard Mountstephens Childs Limited | Professional & scientific | 2011 |
| Barnstaple Investments Ltd | Wholesale & retail | 2024 |
| Baron Security Property Holdings LLP | | 2021 |
| Baron Security Services Limited | Administrative & support | 2000 |
| Barreau Electrical Limited | Construction | 2023 |
| Bars Properties Limited | Real estate | 2004 |
| Barstable Medical Clinic Limited | Administrative & support | 2013 |
| Bart Audi Specialist Ltd | Wholesale & retail | 2020 |
| Bartlowside Management Co. Limited | Households | 1990 |
| Barusya Company Ltd | Health & social care | 2008 |
| Basha Brothers Limited | Construction | 2017 |
| Basildon Health Limited | Health & social care | 2020 |
| Basparam Consulting Limited | Information & communication | 2010 |