| Aspro Tools Limited | Administrative & support | 2019 |
| Asset Home Improvements Ltd | Construction | 2012 |
| Assetgain Limited | Real estate | 2003 |
| AST Interiors Ltd | Construction | 2015 |
| Aster Cottage Limited | Manufacturing | 2024 |
| AT Home Properties Limited | Real estate | 2018 |
| Ataa Properties Ltd | Real estate | 2026 |
| Athena BID Consultancy Ltd | Administrative & support | 2023 |
| Athena Flooring Contracts Limited | Construction | 2012 |
| Athleisure ET ALL Ltd | Wholesale & retail | 2020 |
| Atkinson Home and Build Limited | Administrative & support | 2017 |
| Atlas Care Group Ltd | Health & social care | 2024 |
| Atom Group Holdings Ltd | Financial services | 2023 |
| Atom on Site Limited | Manufacturing | 2016 |
| Atoz Private Limited | Wholesale & retail | 2023 |
| Attic Hall Ltd. | Real estate | 2019 |
| Aura Living Ltd | Real estate | 2021 |
| Aurevienne Labs Ltd | Wholesale & retail | 2025 |
| Aurora Pearl Limited | Arts & recreation | 2013 |
| Aurun Ltd | Wholesale & retail | 2024 |
| Austin Estate Agents Limited | Real estate | 2012 |
| Auto CD Service Ltd | Transport & logistics | 2017 |
| Avails Security Solutions Ltd | Professional & scientific | 2018 |
| Avalon Bloodstock Ltd | Agriculture & fishing | 2014 |
| Avalon Project Management Ltd | Professional & scientific | 2013 |
| Aveat Group Limited | Financial services | 2023 |
| Aveat Heating Limited | Construction | 1978 |
| Avenue Sporting Technology Limited | Information & communication | 2024 |
| Avery Heating & Plumbing Ltd | Construction | 2013 |
| Avery Refrigeration and Air Conditioning Ltd | Construction | 2025 |
| AVH Building Services Limited | Construction | 2001 |
| AVH Holdings Limited | Financial services | 2019 |
| Avis Contracts Ltd | Manufacturing | 2011 |
| Avis Mechanical Limited | Professional & scientific | 1999 |
| Avlc Limited | Construction | 2011 |
| AW Motorworks Limited | Wholesale & retail | 2018 |
| Award Learning Services Limited | Information & communication | 2000 |
| Awgb Properties Limited | Real estate | 2022 |
| Awozan Limited | Wholesale & retail | 2026 |
| AY Creative LLP | | 2026 |
| Ayaz Barber Shop Ltd | Other services | 2021 |
| Ayder Rail Services Ltd | Transport & logistics | 2020 |
| Aykutlar Ltd | Hospitality | 2018 |
| Aznibaan Limited | Wholesale & retail | 2024 |
| Azory Homes Ltd | Real estate | 2024 |
| B & L Sustainable Homes Ltd. | Construction | 2024 |
| B & R Carpentry & Joinery Limited | Construction | 2018 |
| B & W Plastering Ltd | Construction | 2019 |
| B & W Plastering Services Ltd | Construction | 2023 |
| B Cosgrove Limited | Construction | 2018 |
| B Hickman Project Management Limited | Professional & scientific | 2015 |
| B R Construction Services Limited | Professional & scientific | 2016 |
| B&I Home Services Ltd | Other services | 2024 |
| B&M British Maison Ltd | Manufacturing | 2025 |
| B&W Lifts Ltd | Construction | 2019 |
| B. B. B. Farms Limited | Agriculture & fishing | 1962 |
| B.S.W. Marquees Limited | Other services | 1990 |
| Baage Ltd | Real estate | 2020 |
| Baby Ballet Colchester Ltd | Education | 2023 |
| Baby Elephant Investments Limited | Hospitality | 2017 |
| Baby Sparkle Ltd | Administrative & support | 2025 |
| Badger Gate Properties Ltd | Real estate | 2024 |
| Badlands Vintage Clothing Limited | Information & communication | 2011 |
| Bailey & Co. Services Ltd | Transport & logistics | 2026 |
| Bailey Capital Partners Limited | Financial services | 2024 |
| Bailey Investments Ltd | Financial services | 2015 |
| Bainlye Estates Ltd. | Professional & scientific | 2014 |
| Bainlye Holdings Limited | Real estate | 2019 |
| Baker Roofing Solutions Limited | Construction | 2017 |
| Balagam Brothers Ltd | Wholesale & retail | 2020 |
| Balco Precision Engineering Limited | Real estate | 2002 |
| Bamboofeet Ltd | Wholesale & retail | 2008 |
| Bamko UK, Limited | Wholesale & retail | 2012 |
| Banstey Limited | Construction | 2015 |
| Barberhood Braintree Limited | Other services | 2026 |
| Barberhood Essex Limited | Other services | 2023 |
| Barbertime Braintree Ltd | Other services | 2023 |
| Bardfield House Management Limited | Households | 2020 |
| Barker Associates (Essex) Limited | Professional & scientific | 2018 |
| Barker Associates LLP | | 2012 |
| Barker Associates Trustee Limited | Other services | 2023 |
| Barker Cards Ltd | Manufacturing | 2013 |
| Barking Dogs Limited | Hospitality | 2000 |
| Barnes Interiors Limited | Other services | 1996 |
| Barrett and COE Limited | Professional & scientific | 1992 |
| Barrow Property Services Ltd | Households | 2026 |
| Barshields Associates Limited | Real estate | 1994 |
| Bartlett Electrical (Essex) Ltd | Professional & scientific | 2022 |
| BAS Software Solutions Limited | Information & communication | 2001 |
| Base Accountancy Limited | Professional & scientific | 2017 |
| Bash Creative Limited | Professional & scientific | 2015 |
| Basiccroft Limited | Wholesale & retail | 1996 |
| Bassett Developments Limited | Construction | 2025 |
| Bassi's Realty Limited | Real estate | 2021 |
| Bates Real Estates Limited | Real estate | 2017 |
| Battery Storage Enterprises Limited | Energy | 2022 |
| Battery Storage Projects Limited | Energy | 2022 |
| Baverstocks Group Limited | Professional & scientific | 2007 |
| Bay Farm Properties Ltd | Real estate | 2021 |
| Baynham Enterprises Limited | Construction | 2006 |