| citytrafikskolan Norrköping AB | Norrköping | — |
| CityVVS Linköping AB | Linköping | — |
| C&J Behnan Holding AB | Linköping | — |
| CK Söderberg prevention & samverkan AB | Norrköping | — |
| Cleanpal AB | Norrköping | — |
| Cleariva Handelsbolag | Linköping | — |
| CLG Handelsbolag | Motala | — |
| ClientBoost Marketing Handelsbolag | Linköping | — |
| CloudTop AB | Linköping | — |
| C MEDCOIN AB | Linköping | — |
| Coaching by Lindström AB | Linköping | — |
| Collins Gastronomi Handelsbolag | Åtvidaberg | — |
| Colorview Handelsbolag | Linköping | — |
| Comlo AB | Norrköping | — |
| Comlo Holding AB | Norrköping | — |
| Commercia Omnia AB | Kimstad | — |
| CO-M Telecom AB | Motala | — |
| Concresia AB | Norrköping | — |
| Constantin Solutions AB | Norrköping | — |
| Contactive AB | Motala | — |
| Contessa Handelsbolag | Kolmården | — |
| Cooke Education Handelsbolag | Vadstena | — |
| CoreOps AB | Linköping | — |
| Core Principles AB | Linköping | — |
| CORINT AB | Motala | — |
| Cornercraft AB | Söderköping | — |
| Cosode AB | Norrköping | — |
| Coworken AB | Åtvidaberg | — |
| Creative Engineering Engström Östby Handelsbolag | Väderstad | — |
| Crispino Gluten Free AB | Norrköping | — |
| CRO Media Group AB | Linköping | — |
| CR Supply AB | Linköping | — |
| CS Måleri AB | Linköping | — |
| Curafrid AB | Sturefors | — |
| Curling Logistics AB | Norrköping | — |
| Curly Music AB | Vadstena | — |
| Custom by WG AB | Söderköping | — |
| Custom Corner Sweden Handelsbolag | Motala | — |
| CYB Consulting Handelsbolag | Motala | — |
| DA Applications AB | Linköping | — |
| Däckdepån i Norrköping AB | Norrköping | — |
| DAMA Consulting AB | Linköping | — |
| Dandu NeuroConsult AB | Linköping | — |
| Dani & Sandy AB | Norrköping | — |
| Daranyi Barnpsykiatri AB | Linköping | — |
| Darwishi konsult AB | Linköping | — |
| Datapath Design Kommanditbolaget | Norrköping | — |
| David Holding AB | Stockholm | — |
| David Restaurang Handelsbolag | Linköping | — |
| DAVIDS BIL LINKÖPING AB | Linköping | — |