| DSI Data Science Institute | |
| DSI Security Systems, Inc. | Manitoba |
| DSolution | Quebec |
| DSPOne Systems, Inc. | Ontario |
| DSS Distributed Systems Software, Inc. | British Columbia |
| DT Computer Services | Ontario |
| DTI Computers | British Columbia |
| DTM Database Tools | British Columbia |
| DTM soft | British Columbia |
| DTM Systems, Inc. | British Columbia |
| Dual Code, Inc. | Ontario |
| Dublin Bay Ltd | Ontario |
| Dubuc Marketing, Inc. | Quebec |
| Dubyts Communications | Manitoba |
| Ducharme Design Works | British Columbia |
| Duchesnay, Inc. | Quebec |
| Ducktoes Computer Services | Alberta |
| Duco Consulting Ltd | |
| Dudley Thompson Mapping Corporation | British Columbia |
| Duess Design | British Columbia |
| Dugo Systems, Inc. | Nova Scotia |
| Dumont Solutions | Quebec |
| Duncan Instruments Canada Ltd | Ontario |
| Dundas Data Visualization, Inc. | Ontario |
| Dunedain Multimedia, Inc. | Ontario |
| Dunin Technologie | |
| Dunn Engineering, Inc. | Ontario |
| Dunrite! Services | Ontario |
| Duoject | |
| DuplexWeb | |
| Duplium, Inc. | |
| Dura PC, Inc. | Ontario |
| Durable, Inc. | |
| DurableDNS, Inc. | Alberta |
| Durham College | Ontario |
| Durham College - Faculty of Business and Information Technology | Ontario |
| Durham Web Designer | Ontario |
| Durham Web Services | Ontario |
| Durham Website Design | |
| DuroByte | Ontario |
| Duval Marketing | Quebec |
| Duvaltex | |
| DvCom, Inc. | Quebec |
| DVORE | Quebec |
| Dwarika Web Solutions | Ontario |
| Dwellfox | |
| DX3 Canada | Ontario |
| DYAD Infosys Ltd | Ontario |
| Dycor Technologies Ltd | Alberta |
| Dye & Durham Corporation | Ontario |