Although social support is an indispensable resource for coping with illness, the connections among the structural properties of one's support network, received social support from offline and online network members, and well-being are not well understood. This study aims to extend the model of structural-to-functional support by distinguishing offline from online support networks and identifying different pathways through which these two networks contribute to patients' emotional well-being. Using data from 386 cancer patients, the results revealed that offline and online support networks were associated with patients' emotional well-being via different types of received support. Specifically, offline support network size was negatively associated with their emotional well-being via informational support received offline. Online support network size was positively associated with their emotional well-being via emotional support received online.