| 3 Cliff Road CO12 3PP Freehold Ltd | Real estate | 2019 |
| 4 Seasons Grab Hire Ltd | Water & waste | 2017 |
| A D a Construction Services Ltd | Administrative & support | 2015 |
| A FEW Good People Limited | Professional & scientific | 2009 |
| A Smith and Sons Limited | Construction | 1947 |
| A2B Taxis Harwich Limited | Transport & logistics | 2016 |
| Aanneritaa Ltd | Wholesale & retail | 2024 |
| ABC City Ltd | Construction | 2009 |
| Ac.Red Ltd | Transport & logistics | 2017 |
| Accessability Training Ltd | Professional & scientific | 2025 |
| Aceford Limited | | 1987 |
| Ahka Total Care Ltd | Health & social care | 2016 |
| AIO Compliance Limited | Information & communication | 2026 |
| AJM Mobile Tyres & Vehicle Repairs Ltd | Wholesale & retail | 2024 |
| AKS Harwich Ltd | Hospitality | 2023 |
| Albury Business Solutions Ltd | Financial services | 2013 |
| ALL Conditions Treecare Limited | Administrative & support | 2023 |
| Alma at Harwich Limited | Hospitality | 2010 |
| Amari Nautica Ltd | Transport & logistics | 2024 |
| Andrew James Maintenance Ltd | Administrative & support | 2014 |
| Anglo Trade UK Ltd | Wholesale & retail | 2019 |
| Anytime & Sons Solutions Limited | Wholesale & retail | 2023 |
| Apex Pro Group Ltd | Information & communication | 2020 |
| Arul Retail Limited | Wholesale & retail | 2024 |
| Aspens Fire & Security Limited | Administrative & support | 2024 |
| Attwal Construction Ltd | Construction | 2024 |
| Atva Premier Ltd | Wholesale & retail | 2016 |
| Autonomous Maritime Solutions Ltd | Professional & scientific | 2024 |
| Avecox Ltd | Other services | 2024 |
| Avenue Cars Limited | Transport & logistics | 2018 |
| AW Consulting Services Limited | Professional & scientific | 2016 |
| Ayton Interiors Ltd | Construction | 2019 |
| B Burlington Limited | Transport & logistics | 2025 |
| Baldwins of Dovercourt Limited | Wholesale & retail | 2021 |
| Baldwins Own Buy Ltd | Wholesale & retail | 2025 |
| Ballyroan Construction Limited | Professional & scientific | 2013 |
| Barley Meadow Residents Company Limited | Households | 2002 |
| Barnard Memorial Restorations Ltd | Other services | 2026 |
| Baycat Digital Limited | Information & communication | 2015 |
| BC Creatives Ltd | Professional & scientific | 2024 |
| Beach View Apartments Limited | Households | 2016 |
| Beautybydesignx Limited | Other services | 2025 |
| Beca Logistics Limited | Transport & logistics | 2025 |
| Beez Security Company Ltd | Administrative & support | 2023 |
| Bespoke Therapy and Advocacy Service Ltd | Professional & scientific | 2013 |
| Bessafe Ltd | Professional & scientific | 2026 |
| Better Fit Solutions Ltd | Construction | 2021 |
| Big M Ltd | Construction | 2016 |
| Bill Clinic Ltd | Extraterritorial | 2022 |
| BJN Consultancy Limited | Arts & recreation | 2024 |
| BK Turbotransport Ltd | Transport & logistics | 2025 |
| Blackstars African Market Ltd | Wholesale & retail | 2025 |
| Blindsbycatherine Ltd | Wholesale & retail | 2026 |
| Bluesteel International Limited | Administrative & support | 2015 |
| Bonthrone Companies Ltd | Wholesale & retail | 2005 |
| Book Time Ltd | Information & communication | 2022 |
| Boranefe Limited | Hospitality | 2024 |
| Boysie Developments Limited | Construction | 2020 |
| Bradley's Car Cosmetics Ltd | Wholesale & retail | 2019 |
| Briarsfield Systems Ltd | Professional & scientific | 2025 |
| Bridge 2 Education & Employment Limited | Education | 2026 |
| Bridgefoot Farm & Stables Limited | Agriculture & fishing | 2017 |
| Bridgefoot Farm Boarding Kennels Limited | Agriculture & fishing | 2026 |
| Bridges Heating and Cooling Ltd | Construction | 2022 |
| Brointermed Lines Limited | Transport & logistics | 1998 |
| BRONZE2 Ltd | Other services | 2024 |
| Brooklyn Court (Dovercourt) Management Company Limited | Real estate | 2008 |
| Build Plumb Plastics Ltd | Wholesale & retail | 2009 |
| BUMP2BEAUTY Ltd | Wholesale & retail | 2025 |
| Burwood-Coe Property Ltd | Real estate | 2023 |
| C & C Surfacing Ltd | Construction | 2007 |
| C Bull Limited | Construction | 2018 |
| C J Wills Ltd | Construction | 2021 |
| C.R.Bayley Ltd | Construction | 2011 |
| Cabin Foodhouse Ltd | Wholesale & retail | 2017 |
| Callum Boyne Limited | Construction | 2018 |
| Care Jobs Harwich Limited | Health & social care | 2020 |
| Carmichael Plumbing & Heating Limited | Construction | 2025 |
| Carter Michaelson Limited | Professional & scientific | 2018 |
| Case Construction and Development Limited | Construction | 2018 |
| Case Property & Developments Limited | Construction | 2020 |
| Caxab Limited | Financial services | 2026 |
| Cayenne Catering Ltd | Hospitality | 2010 |
| Cgmotors Ltd | Wholesale & retail | 2019 |
| Changlong Trading Ltd | Hospitality | 2019 |
| Character Locksmith Ltd | Manufacturing | 2025 |
| Charlotte Briscoe Interiors Ltd | Manufacturing | 2024 |
| Chris Jones Joinery and Carpentry Limited | Manufacturing | 2022 |
| CJT Group Ltd | Professional & scientific | 2015 |
| Clarkehaus New Homes Ltd | Construction | 2021 |
| Clarkehaus Sales & Lettings Limited | Real estate | 2021 |
| Cleanwater Ltd | Wholesale & retail | 2009 |
| Clifton Contracts (Harwich) Limited | Construction | 1988 |
| Clinical Equipment Consultants Limited | Professional & scientific | 2015 |
| Cluetopia Colchester Ltd | Arts & recreation | 2026 |
| CMJ Compny Limited | Real estate | 2023 |
| Co Fitness Ltd | Arts & recreation | 2026 |
| Co Fitness Reformer Ltd | Arts & recreation | 2026 |
| Colourful Medic Healthcare Limited | Health & social care | 2025 |
| Compass (Harwich) Ltd | Real estate | 2006 |