| Chesil Beach Mews Management Limited | Households | 2025 |
| Chesil Beach Properties Limited | Real estate | 2020 |
| Chesil Beach Specialist Contractors Limited | Construction | 2025 |
| Chesil Chippie & Fish Bar Limited | Hospitality | 2015 |
| Chesil Chippie Catering Ltd | Hospitality | 2020 |
| Chesil Court Weymouth Limited | Households | 1995 |
| Chesil Edge Cleaning Services Limited | Administrative & support | 2021 |
| Chesil Financial Planning Ltd | Financial services | 2022 |
| Chesil Property Maintenance Ltd | Construction | 2023 |
| Chesil Roastery Limited | Hospitality | 2025 |
| Chesil Studios Ltd | Professional & scientific | 2025 |
| Chesterman and Matthews Scaffolding Limited | Construction | 2015 |
| Chic Weymouth Limited | Other services | 2012 |
| Chickerell Codfathers Limited | Hospitality | 2024 |
| Chickerell Developments Limited | Real estate | 2020 |
| Chideock Grange Ltd | Hospitality | 2014 |
| Chilli Churchill Ltd | Construction | 2021 |
| Chillifish Ltd | Arts & recreation | 2020 |
| Chipmunks Day Nursery Limited | Health & social care | 2012 |
| Chipping Software Limited | Extraterritorial | 1995 |
| Chips Ahoy (Weymouth) Limited | Wholesale & retail | 2003 |
| CHK Surveying and Engineering Ltd | Construction | 2018 |
| Chris Goodwin Building Services Limited | Administrative & support | 2006 |
| Chris Norcott Building Ltd | Construction | 2011 |
| Christmas & Brugge Ltd | Professional & scientific | 2003 |
| Christopher David Limited | Professional & scientific | 2009 |
| Chronos Ventures Limited | Professional & scientific | 2020 |
| Churchill Gardens Management Company Limited | Households | 2005 |
| Ciniture Ltd | Manufacturing | 2021 |
| Cinnamon Spice Weymouth Ltd | Hospitality | 2025 |
| CJ Developments & Construction Ltd | Construction | 2023 |
| CJ Mortgage Hub Limited | Financial services | 2023 |
| CJK Electrical Services Limited | Construction | 2025 |
| CL Ocean City Limited | Hospitality | 2023 |
| Cladding Consultants (UK) Limited | Extraterritorial | 2004 |
| Cladworks Ltd | Construction | 2018 |
| Clarence House (Weymouth) Limited | Construction | 1950 |
| Clarin Aviation Ltd | Other services | 2022 |
| Clarin Education Ltd | Other services | 2022 |
| Clarin Properties Ltd | Households | 2022 |
| Clarin Trading Ltd | Other services | 2022 |
| Clark Brooks Access Limited | Construction | 2005 |
| Clark's Boatworks Limited | Manufacturing | 2003 |
| Clarkes Windows Limited | Construction | 2009 |
| Classic Modern Cars Limited | Wholesale & retail | 2016 |
| Clayson Holdings Limited | Financial services | 2015 |
| Clayson Scaffolding Limited | Construction | 2012 |
| Clayton Construction Ltd | Construction | 2014 |
| Clean AS a Whistle Dorset Ltd | Administrative & support | 2021 |
| Clear Restoration Whitehaven Ltd | Real estate | 2022 |
| Clear View Farm Limited | Agriculture & fishing | 2019 |
| Clearasaurus Ltd | Water & waste | 2025 |
| Clearer Horizons CIC | Education | 2023 |
| Cleveland House (Weymouth) Limited | Households | 1957 |
| Click to Book Ltd | Information & communication | 2024 |
| Clifton Hotel Weymouth Ltd | Hospitality | 2015 |
| Clout Limited | Administrative & support | 2010 |
| Clover Cabinet Makers Ltd | Manufacturing | 2022 |
| CM Energy UK (Weymouth) Ltd | Administrative & support | 2013 |
| CMB Engineering Services Limited | Professional & scientific | 1989 |
| CMH Leadwork and Roofing Services Ltd | Construction | 2020 |
| Coaching Helps Limited | Professional & scientific | 2015 |
| Coast 2 Coast Haulage Ltd | Transport & logistics | 2009 |
| Coast and County Homes Limited | Real estate | 2024 |
| Coast Software Limited | Information & communication | 2009 |
| Coastal Culture Ltd | Wholesale & retail | 2025 |
| Coastal Customs Ltd | Other services | 2017 |
| Coastal HR Consultancy Limited | Administrative & support | 2025 |
| Coastal Lettings & Property Management Limited | Real estate | 2017 |
| Coastal Tree Care Limited | Agriculture & fishing | 2015 |
| Coastalcombatleague Ltd | Arts & recreation | 2025 |
| Coastline Covers Ltd | Construction | 2002 |
| Coastline Cruises Ltd | Transport & logistics | 1999 |
| Coastline Developments (Dorset) LLP | | 2017 |
| Coastline Plumbing and Maintenance Ltd | Construction | 2017 |
| Cobblekeys Limited | Wholesale & retail | 2016 |
| Coco Property Group Limited | Real estate | 2023 |
| Coffee Jazz Ltd | Manufacturing | 2023 |
| Cohort Computers Limited | Wholesale & retail | 2001 |
| Colin Bover Limited | Construction | 2003 |
| Commando Heating Ltd | Professional & scientific | 2025 |
| Compass MC Limited | Professional & scientific | 2022 |
| Compass Rose Marine Consultancy Ltd | Professional & scientific | 2009 |
| Complete Installation Solutions Limited | Construction | 2004 |
| Complete Renewable Services Ltd | Construction | 2022 |
| Completely Floored in Weymouth Ltd | Wholesale & retail | 2012 |
| Connect Sphere Ltd | Information & communication | 2024 |
| Conscar Limited | Transport & logistics | 2017 |
| Considerate Freehold Management Ltd | Real estate | 2022 |
| Construction & Maintenance (Dorset) Limited | Construction | 2010 |
| Consultancy, Coaching and HR Services Limited | Professional & scientific | 2009 |
| Contanti Limited | Extraterritorial | 2006 |
| Conteq International Ltd | Information & communication | 2021 |
| Conutrol Instrument Services Limited | Professional & scientific | 2017 |
| Cooke Construction Limited | Construction | 2004 |
| Cooke Contracts Limited | Construction | 2025 |
| Cookie(Uk) Ltd | Administrative & support | 2022 |
| Cooknell Electronics Limited | Manufacturing | 1989 |
| Coombe Farm Cattery Limited | Other services | 2026 |
| Cooper and Cooper Investments Ltd | Real estate | 2021 |