| Connolly Accountancy Services Ltd | Professional & scientific | 2022 |
| Conor Sally & Co Ltd | Professional & scientific | 2018 |
| Constructionpal Ltd | Administrative & support | 2023 |
| Contract Ground Services Ltd | Construction | 2015 |
| Contract Services (N.I.) Limited | Construction | 2015 |
| Conway Carpets Ltd | Wholesale & retail | 2015 |
| Conway Construction & Plumbing Ltd | Construction | 2020 |
| Conway Design and Innovation Ltd | Professional & scientific | 2019 |
| Conway MC Beth Limited | Administrative & support | 2013 |
| Coolaghy Ltd | Financial services | 2025 |
| Coolaghy Property Management Ltd | Administrative & support | 2012 |
| Coolfuel Ltd | Manufacturing | 2020 |
| Coolhill Construction & Hire Ltd | Construction | 2025 |
| Coolnagard Hollow Management Company Ltd | Households | 2006 |
| Copney Farm Estate Ltd | Real estate | 2023 |
| COR Group Limited | Financial services | 2025 |
| Cora Developments Limited | Construction | 2016 |
| Corbo Distributions Ltd | Wholesale & retail | 2024 |
| Corbo Farms Ltd | Agriculture & fishing | 2026 |
| Corcoran Control Holdings | Financial services | 2016 |
| Core Growth Ltd | Administrative & support | 2025 |
| Core Kids Ltd | Education | 2019 |
| Core Smartfit Community Interest Company | Other services | 2018 |
| Corkhill Holdings Ltd | Energy | 2015 |
| Corkhill Ltd | Agriculture & fishing | 2015 |
| Corlea Enterprises Ltd | Energy | 2015 |
| Corlin Limited | Construction | 2014 |
| Cornabracken - Afterschool C.I.C. | Health & social care | 2015 |
| Cornabracken at CKS Ltd | Health & social care | 2024 |
| Cornabracken Childcare Limited | Health & social care | 2014 |
| Cornerstone Developments (Omagh) Ltd | Construction | 2006 |
| Corr Performance Ltd | Wholesale & retail | 2021 |
| Corra Contracts Limited | Construction | 2009 |
| Corrigan Building Designs Ltd | Professional & scientific | 2019 |
| Corrigan Contracts Limited | Construction | 2019 |
| Corrigan Properties Ltd | Real estate | 2025 |
| Corrigs Consultancy Ltd | Professional & scientific | 2025 |
| Corrprop Ltd | Real estate | 2023 |
| Corry & O'Hare Vets Ltd. | Professional & scientific | 2019 |
| Corry and Stewart Estate Agents Limited | Real estate | 2018 |
| Corryglass Farm Ltd | Agriculture & fishing | 2017 |
| Corvan Campers Limited | Hospitality | 2022 |
| Costello Structural Design Ltd | Professional & scientific | 2025 |
| Country Hobo Limited | Wholesale & retail | 2024 |
| Countrywide Homes (NI) Limited | Construction | 2014 |
| Course Delivery Hero's Ltd | Professional & scientific | 2026 |
| Coyle Decor Ltd | Construction | 2002 |
| Coyle Suspended Ceilings Ltd | Construction | 2010 |
| CP Accounts (NI) Ltd | Extraterritorial | 2025 |
| CP Logue Enterprises Ltd | Real estate | 2025 |
| CPD Liquors Ltd | Hospitality | 2023 |
| CPD Promotions Ltd | Hospitality | 2025 |
| CPK Electrical Ltd | Construction | 2023 |
| CPM Construction Group Ltd | Professional & scientific | 2019 |
| CPM Electrical Ltd | Construction | 2012 |
| CPM Trading Ltd | Construction | 2010 |
| CR Signs Ltd | Professional & scientific | 2017 |
| Craig-Crosh Poultry Ltd | Agriculture & fishing | 2026 |
| Craig-Crosh Properties Limited | Construction | 2005 |
| Craignamaddy Ltd | Financial services | 2017 |
| Cranfield Developments Limited | Construction | 2009 |
| Cranny Farms Ltd | Wholesale & retail | 2024 |
| Crawford & Wilson Limited | Wholesale & retail | 1926 |
| Crawford Mchugh Ltd | Wholesale & retail | 2025 |
| CRD Holdings Ltd | Financial services | 2023 |
| Creative Arts and Music Ltd | Education | 2025 |
| Creevanmore Services Ltd | Wholesale & retail | 2017 |
| Creggan Business Development Ltd | Public administration | 2016 |
| Creggan Community Association | Arts & recreation | 1999 |
| Creggan Community Developments Ltd | Construction | 2017 |
| Creggan PIG Farms Ltd | Agriculture & fishing | 2021 |
| Creggan Tourism Ltd | Arts & recreation | 1997 |
| Creggandevesky Wind Ltd | Energy | 2016 |
| Crescent (NI) Management Company Ltd | Real estate | 2008 |
| Crevenagh Group Ltd | Transport & logistics | 2024 |
| Crevenagh Investments Limited | Real estate | 2016 |
| Crillyville Limited | Real estate | 2016 |
| CRO Co Coffee Limited | Manufacturing | 2018 |
| Cro/Mec Ltd | Professional & scientific | 2021 |
| Crocan Eggs Limited | Manufacturing | 2016 |
| Crocan Ltd | Financial services | 2011 |
| Crockanboy Cabins Ltd | Hospitality | 2023 |
| Crockanboy Wind Limited | Energy | 2017 |
| Crockhill Contracts Limited | Construction | 2020 |
| Crocknagrogan Limited | Energy | 2012 |
| Crosh Valley Contracts Ltd | Construction | 2008 |
| Crosh Valley Pigs Limited | Agriculture & fishing | 2017 |
| Cross 24/7 Ltd | Extraterritorial | 2013 |
| Cross Energies Ltd | Professional & scientific | 2009 |
| Cross Farms Limited | Agriculture & fishing | 2013 |
| Crossfit Omagh Ltd | Arts & recreation | 2020 |
| Crosshill Energy Limited | Energy | 2012 |
| CRS Hire and Recycling Rentals Ltd | Administrative & support | 2019 |
| Crusher Screen Parts Ltd | Wholesale & retail | 2022 |
| Crystal Skin Clinic Ltd | Other services | 2017 |
| CSC Properties Ltd | Real estate | 2024 |
| CSD Communications Ltd | Information & communication | 2018 |
| CSM Commercial Ltd | Financial services | 2024 |
| CSM Holdings Ltd | Financial services | 2015 |
| Csoccdr MCD Ltd | Financial services | 2022 |