| Callan Contracts Limited | Construction | 2014 |
| Callowhill Farms Limited | Agriculture & fishing | 2026 |
| Calry Properties Ltd | Real estate | 2006 |
| CAM Trac Limited | Wholesale & retail | 2021 |
| Camber Developments Limited | Real estate | 2006 |
| Camica Ltd | Real estate | 2022 |
| Campbell Quarries Ltd | Mining & quarrying | 2025 |
| Campbell Solutions Limited | Construction | 2011 |
| Cancer Connect NI | Health & social care | 2009 |
| Candy Shop North Limited | Wholesale & retail | 2026 |
| Cara Contracts Limited | Construction | 2019 |
| Cara Veterinary Clinic Ltd | Professional & scientific | 2023 |
| Care Direct 24/7 Group Limited | Health & social care | 2024 |
| Care Plus (N.I.) Ltd | Health & social care | 2016 |
| Carewell Homes Contract Services Ltd | Administrative & support | 2023 |
| Carewell Homes Limited | Health & social care | 1990 |
| Carey Brothers Ltd | Transport & logistics | 2016 |
| Carey Roofing Limited | Construction | 2023 |
| Carl Sullivan Cycles Ltd | Wholesale & retail | 2025 |
| Carn Music Limited | Arts & recreation | 2017 |
| Carneyhill Garden Services Ltd | Administrative & support | 2025 |
| Carnmore Stone Limited | Manufacturing | 1996 |
| Carolan Contracts Limited | Construction | 2003 |
| Carran Properties Limited | Real estate | 1991 |
| Carrickbeg Properties Limited | Real estate | 2004 |
| Carrickreagh Bay Ltd | Hospitality | 2020 |
| Carron IT Consulting Ltd | Information & communication | 2020 |
| Carrs Property Limited | Real estate | 2025 |
| Carry on Glamping Limited | Construction | 2024 |
| Carter Medical Limited | Health & social care | 2023 |
| Casa Narrative Ltd | Wholesale & retail | 2024 |
| Cashel Investments Limited | Financial services | 2007 |
| Cassidy & Mccreesh Orthodontic Practice Limited | Health & social care | 2020 |
| Cassidy Mechanical Limited | Construction | 2024 |
| Cassidy Retail Ltd | Wholesale & retail | 2025 |
| Cassidy's Poultry Ltd | Agriculture & fishing | 2023 |
| Castle Archdale Boat Hire and Watersports Ltd | Arts & recreation | 2018 |
| Castle Archdale Marina Ltd | Arts & recreation | 1995 |
| Castle Archdale Retail Ltd | Wholesale & retail | 2015 |
| Castle Food Services Ltd | Wholesale & retail | 2018 |
| Castle Gate Marina Ltd | Construction | 2019 |
| Castle Hume Court | Financial services | 2018 |
| Castlecoole Holdings Ltd | Wholesale & retail | 2025 |
| Castlecoole Manor Management Co. Ltd | Real estate | 2015 |
| Castlecoole Properties Limited | Real estate | 2022 |
| Castlehill Tractors Ltd | Wholesale & retail | 2025 |
| Castlemonea Management Company Limited | Real estate | 2010 |
| Castlennis Management Limited | Real estate | 2001 |
| Catalina Bay Limited | Extraterritorial | 2009 |
| Catar Limited | Hospitality | 2014 |
| Catering HQ Limited | Manufacturing | 2011 |
| Cathcart Contracts Ltd | Manufacturing | 2018 |
| Cathcart Holdings Limited | Financial services | 2020 |
| Cats Cradle Productions Ltd | Information & communication | 2022 |
| Cavan Fermanagh Leitrim Community Group CIC | Mining & quarrying | 2021 |
| CB Properties and Rentals Ltd | Real estate | 2024 |
| CBR Consultancy Services Ltd | Professional & scientific | 2026 |
| CCD Investments Ltd | Real estate | 2026 |
| CCJ Solutions Ltd | Real estate | 2020 |
| CCM Autobody Repairs Ltd | Wholesale & retail | 2025 |
| CD Consulting (N.I) Ltd | Professional & scientific | 2020 |
| CDD Childcare Services Ltd | Education | 2016 |
| Ceannfort Ltd | Professional & scientific | 2026 |
| Cecil Elliott & Sons Ltd | Transport & logistics | 1999 |
| Centra Belleek Ltd | Wholesale & retail | 2022 |
| Ceramics Direct Limited | Wholesale & retail | 2000 |
| Chairway to Heaven Ltd | Wholesale & retail | 2025 |
| Chanterhill Developments Ltd | Construction | 2015 |
| Chaocao Bying Limited | Wholesale & retail | 2025 |
| Charles Male Grooming Ltd | Other services | 2019 |
| Charlie's Bar (Enniskillen) Limited | Hospitality | 2024 |
| Cherish Life Property Group Ltd | Financial services | 2026 |
| Chernobyl Children Appeal (NI) Ltd | Health & social care | 1996 |
| China City BT74 Limited | Hospitality | 2025 |
| Chirpy Bird Food Limited | Wholesale & retail | 2016 |
| Church Meadows (Clabby) Management Ltd | Households | 2020 |
| CI Automation Ltd | Construction | 2022 |
| Ciaranmandysean Property Developments Ltd | Construction | 2025 |
| Circuits Alive Limited | Professional & scientific | 1998 |
| CJG Groundworks Limited | Construction | 2018 |
| CJO Entertainment Ltd | Arts & recreation | 2024 |
| CJP at Height Services Limited | Construction | 2018 |
| CJS Technology Services Ltd | Information & communication | 2025 |
| CL 3 Limited | Arts & recreation | 2019 |
| CL Financial Services (Enniskillen) Ltd | Financial services | 2017 |
| Clado Ltd | Hospitality | 2022 |
| Claire Mulligan Opticians Limited | Wholesale & retail | 2012 |
| Clarbiz Limited | Administrative & support | 2019 |
| Clarhen Group Limited | Hospitality | 2026 |
| Cleaning Doctor Limited | Administrative & support | 1998 |
| Clear Plant Trading (NI) Limited | Wholesale & retail | 2013 |
| Cleenish Community Association | Other services | 2004 |
| Cleenish Island Lamb Limited | Wholesale & retail | 2025 |
| Cleenish Renewal Co Ltd - the | Other services | 2006 |
| Cliff Street Properties Ltd | Real estate | 2024 |
| Cliff Street Trading Limited | Hospitality | 2020 |
| Clive Alexander Ltd | Other services | 2014 |
| CLM Estates Limited | Real estate | 2007 |
| Cloghanramer 2026 Limited | Real estate | 2026 |
| Clonahinch Enterprises Ltd | Agriculture & fishing | 2023 |