| Civils Rigid Limited | Construction | 2013 |
| CJC Demolition Ltd | Construction | 2025 |
| CK GAS Services Limited | Construction | 2026 |
| CKC Construction and Engineering Limited | Professional & scientific | 2019 |
| Claragh Coded Welding Ltd | Manufacturing | 2022 |
| Claran Court Limited | Real estate | 2023 |
| Claremount FM Limited | Professional & scientific | 2011 |
| Clarendon Chiropractic Clinic Limited | Health & social care | 1998 |
| Classic Blinds & Interiors (UK) Limited | Wholesale & retail | 2021 |
| Classique Floor Designs Ltd | Construction | 2005 |
| Claudes Cafe Ltd | Hospitality | 2010 |
| Clearview Orangeries Ltd | Construction | 2021 |
| Click Homepage Ltd | Professional & scientific | 2018 |
| Clifmac Limited | Construction | 2020 |
| Cloudkeeper Systems Ltd | Information & communication | 2025 |
| CM Property Management Ltd | Real estate | 2004 |
| CMD Cleaning Ltd | Administrative & support | 2023 |
| CMF1985 Electrical Services Limited | Professional & scientific | 2015 |
| Cmkennedy Limited | Hospitality | 2019 |
| CML Cloud Solutions Ltd | Information & communication | 2021 |
| CN Cloud Consulting Limited | Information & communication | 2022 |
| Co'Donnell Electrics Limited | Construction | 2025 |
| Coer Developments Limited | Real estate | 2014 |
| Cojaniel Limited | Wholesale & retail | 2018 |
| Colin Dooher Ltd | Professional & scientific | 2017 |
| Colo Plant Limited | Administrative & support | 2015 |
| Comip Limited | Real estate | 2021 |
| Commodore Amusements Limited | Arts & recreation | 1998 |
| Commodore Leisure & Entertainments Limited | Arts & recreation | 1995 |
| Commtec Services Ltd | Manufacturing | 2020 |
| Conall Mellon Electrical Limited | Construction | 2022 |
| Conlith Limited | Wholesale & retail | 2025 |
| Conor Devir Fitness Coach Ltd | Arts & recreation | 2024 |
| Construction Marketing Consultants Ltd | Construction | 2012 |
| Continuous Recruitment Solutions Limited | Administrative & support | 2017 |
| Convis Enterprises Limited | Wholesale & retail | 2002 |
| Corecare Counselling and Psychotherapeutic Services Ltd | Health & social care | 2024 |
| Corfields Property Investments Limited | Real estate | 2025 |
| Corrody Developments Management Company Limited | Households | 2025 |
| Cosworth Properties Limited | Households | 2005 |
| Countrywide Landscapes Limited | Administrative & support | 2003 |
| Cowan ALL Purpose Glass Ltd | Manufacturing | 2022 |
| CPH Services Ltd | Construction | 2021 |
| CPW Elec Ltd | Construction | 2024 |
| Cracka Dawn Ltd | Manufacturing | 2024 |
| Crampsey Construction Ltd | Construction | 2003 |
| Cranford Stone UK Ltd | Mining & quarrying | 2021 |
| Crawford Mason Administrative Services Limited | Professional & scientific | 2019 |
| Create the City Ltd | Information & communication | 2023 |
| Credit Solutions (Ireland) Ltd | Financial services | 2008 |
| Creggan Bakery Limited | Wholesale & retail | 2025 |
| Crossfit Derry Limited | Arts & recreation | 2023 |
| CSJ Developments (NI) Ltd | Real estate | 2022 |
| Culmore Community Partnership Ltd | Other services | 2018 |
| Culmore Enterprises Limited | Construction | 1990 |
| Cultura Resources (NI) Limited | Other services | 2018 |
| Curavita Group Ltd | Financial services | 2024 |
| Currys Properties Ltd | Hospitality | 2026 |
| D C Crystal Ltd | Wholesale & retail | 2016 |
| D Callaghan Electrical 1 Ltd | Wholesale & retail | 2022 |
| D Devlin Ltd | Health & social care | 2026 |
| D R Properties NW Ltd | Real estate | 2025 |
| D&G Hogan (Park Avenue) Ltd | Hospitality | 2016 |
| D. Bradley Engineering Ltd | Construction | 2024 |
| D. Harkin & Company (Roofing) Limited | Construction | 2000 |
| D.H. Marine Solutions Ltd | Other services | 2012 |
| D.S.S Plant Contracts Ltd | Construction | 2026 |
| Dale Mccormick Trading Limited | Construction | 2025 |
| Dalton Farm Produce Limited | Agriculture & fishing | 2014 |
| Daly Bros. Retail NI Limited | Wholesale & retail | 2021 |
| Daniel Rule Limited | Wholesale & retail | 2016 |
| Danu Aesthetics Limited | Health & social care | 2023 |
| Dartan Investments Limited | Real estate | 1996 |
| Davey Skips NI Limited | Water & waste | 2018 |
| David Hetherington Haulage NI Ltd | Transport & logistics | 2025 |
| DB Kitchen Ltd | Hospitality | 2019 |
| DB Utility Services Ltd | Construction | 2022 |
| Dbok Ltd | Real estate | 2017 |
| DC Bespoke Joinery & Construction Limited | Construction | 2024 |
| DC Catering Equipment Ltd | Wholesale & retail | 2024 |
| DC Fuels NI Ltd | Wholesale & retail | 2026 |
| DCV Mcdaid UK Limited | Real estate | 2019 |
| DE Productions Ltd | Information & communication | 2026 |
| Deccs (Ireland) Ltd | Professional & scientific | 2008 |
| Decsm Ltd | Information & communication | 2020 |
| Deegall Limited | Professional & scientific | 2020 |
| Deerpark Haulage Ltd | Transport & logistics | 2013 |
| Deery Design Ltd | Construction | 2018 |
| Deery Electrical Limited | Professional & scientific | 2024 |
| Deke Ltd | Real estate | 2015 |
| Deluxe Media Walls & Design Limited | Construction | 2023 |
| Demb Holdings Limited | Financial services | 2024 |
| Demco Limited | Real estate | 1988 |
| Derham Hospitality Ltd | Hospitality | 2024 |
| Derma Skincare Clinic Limited | Wholesale & retail | 2026 |
| Derrai Ltd | Information & communication | 2026 |
| Derry BUS Ltd | Transport & logistics | 2018 |
| Derry City Football Club Ltd | Arts & recreation | 2009 |
| Derry Guided Tours Limited | Administrative & support | 2025 |
| Derry Plumbing Limited | Construction | 2021 |