Background: Patient engagement is critical for realizing the value of telehealth modalities such as the patient portal. Family caregiver engagement may also be critical for facilitating the use of the patient portal among adult patients, including older adults. Objective: This study aims to analyze the 2019 Health Information National Trends Survey to characterize family caregivers’ use of their care recipient’s patient portal in terms of sociodemographic, health, and caregiving characteristics and caregivers’ use of their own portal.