| Cinch Corsets Limited | Manufacturing | 2015 |
| Claire Ritchie Travel Ltd | Administrative & support | 2025 |
| Clarehill Developments Limited | Construction | 1978 |
| Clarke Advisory Ltd. | Professional & scientific | 2026 |
| Clarke Brookville Ltd | Financial services | 2025 |
| Clendinning (Holdings) Limited | Financial services | 1960 |
| Clever Ghost Ltd | Professional & scientific | 2018 |
| Clodan Limited | Hospitality | 2016 |
| Club Engine X Ltd | Information & communication | 2026 |
| CMP Creative Ltd | Professional & scientific | 2024 |
| Coast to Coast Newcastle Ltd | Hospitality | 2021 |
| Coby Investments Limited | Professional & scientific | 2022 |
| Coco Lodge Properties Ltd | Real estate | 2021 |
| Coffee BT18 Ltd | Hospitality | 2018 |
| Coffee Yard Ltd | Hospitality | 2009 |
| Coflo Consultancy Limited | Professional & scientific | 2025 |
| Cohara Limited | Real estate | 2021 |
| Cohort Living Limited | Real estate | 2024 |
| Cohort Living Propco 003 Limited | Financial services | 2020 |
| Coleraine Coffee Ltd | Transport & logistics | 2018 |
| Colinwell Concrete Limited | Real estate | 1962 |
| Colinwell Properties Holdings Limited | Financial services | 2021 |
| Complex Print Media Ltd | Manufacturing | 2020 |
| Condor Club Limited | Arts & recreation | 2026 |
| Confluence Consulting N.I. Limited | Professional & scientific | 2023 |
| Consort (N.I.) Limited | Professional & scientific | 2015 |
| Contacts Plus Limited | Other services | 2017 |
| Content Press & Media Ltd | Information & communication | 2018 |
| Controvert Ltd | Manufacturing | 2015 |
| Cooptical Group Ltd | Wholesale & retail | 2022 |
| Cooptical Ltd. | Wholesale & retail | 2013 |
| Copper Green Management Company Limited | Extraterritorial | 2016 |
| Cormac Ltd | Hospitality | 2023 |
| Corner Flag Management Limited | Arts & recreation | 2003 |
| Corporation Investments Limited | Real estate | 2014 |
| Cosmetech Clinics Limited | Health & social care | 2007 |
| Cpr-Consultancy Ltd | Professional & scientific | 2023 |
| CR Financial Planning Limited | Professional & scientific | 2015 |
| Craigantlet Landscapes Limited | Administrative & support | 2020 |
| Cranmore Consulting Limited | Information & communication | 2008 |
| Cranmore Group Limited | Financial services | 2023 |
| Cranmore Holdings Ltd | Real estate | 2020 |
| Craven Street Partners LP | | 2015 |
| Crawford and Linden Limited | Professional & scientific | 2023 |
| CRD (N.I.) Limited | Real estate | 2020 |
| Create Express Ltd | Professional & scientific | 2003 |
| Creative Ashram Limited | Other services | 2026 |
| Creche Nurseryco Limited | Education | 1994 |
| Crjc Properties Limited | Hospitality | 2018 |
| Croft Management Company (Down) Limited | Real estate | 2007 |
| Crofton Property Group Ltd | Construction | 2026 |
| Cromwell Court Limited | Households | 2001 |
| Crown Bookmakers Limited | Arts & recreation | 1979 |
| CRP Labs Ltd | Wholesale & retail | 2026 |
| CTC (N.I.) Ltd | Other services | 2015 |
| Culinary Concepts (Hospitality) Limited | Other services | 2022 |
| Cultra Developments Ltd | Construction | 2012 |
| Cultra Properties Ltd | Construction | 2012 |
| Curzon Capital IRE Ltd. | Real estate | 2016 |
| D Quick Media Ltd | Information & communication | 2022 |
| DAG Residential Ltd | Real estate | 2026 |
| Dakota Capella LLP | | 2017 |
| Dakota Partners Carry LLP | | 2017 |
| Dakota Partners Limited | Real estate | 2016 |
| Dancing Leopards Ltd | Other services | 2006 |
| Daniel James Creative Ltd | Professional & scientific | 2025 |
| Daniel Mccabe Sound Ltd | Information & communication | 2023 |
| Darvicar Limited | Financial services | 2025 |
| Datnap Limited | Financial services | 2022 |
| David Meade Limited | Information & communication | 2012 |
| David Sweet Paediatrics Ltd | Health & social care | 2020 |
| Daybreak Investments Ltd | Real estate | 2023 |
| DC13RV Limited | Professional & scientific | 2015 |
| Dckni Limited | Health & social care | 2011 |
| Derek Hamilton Limited | Wholesale & retail | 1995 |
| Design and Management Limited | Professional & scientific | 2022 |
| Design by Omak Ltd | Wholesale & retail | 2023 |
| Digital 12 Limited | Information & communication | 2019 |
| Dillons Grange Management Company Limited | Households | 2007 |
| Distribrands Corp Ltd | Wholesale & retail | 2023 |
| Djmurrs Ltd | Administrative & support | 2024 |
| Dogs Life Pet Services Ltd | Agriculture & fishing | 2024 |
| Donaldson Planning Limited | Professional & scientific | 2017 |
| Dormie Golf Limited | Wholesale & retail | 2021 |
| Down Construction Company Limited | Extraterritorial | 1994 |
| Downshire Auto Repairs Limited | Wholesale & retail | 2019 |
| Downshire Partners I LP | | 2018 |
| Downshire Partners II LP | | 2022 |
| Downshire Partners III LP | | 2018 |
| Downshire Partners VII LP | | 2022 |
| Dozer Useful Ltd. | Manufacturing | 2026 |
| DR Angela Mcgreevy Ltd | Extraterritorial | 2012 |
| DR Paul Chan Ltd | Extraterritorial | 2012 |
| Dragon Claw Whiskey Ltd | Manufacturing | 2021 |
| DRD Manufacturing Solutions Ltd | Professional & scientific | 2014 |
| Drumalane Limited | Construction | 2008 |
| Drumhill Construction Limited | Construction | 2009 |
| Drumlin Management Ltd | Extraterritorial | 2012 |
| Drummaul Enterprises Ltd | Hospitality | 2023 |
| Drummaul House Limited | Health & social care | 1987 |