The use of digital medical consent forms in the healthcare process can not only improve medical efficiency and physician–patient communication, but also reduce paper document storage space and costs. Although many hospitals have overcome difficulties in adopting digital medical consent forms, the willingness of patients and their families to sign digital medical consent forms is low. However, the literature directly related to healthcare consumers’ signing behavior toward digital medical consent forms is scant. Thus, the purpose of this study was to integrate the decomposition theory of planned behavior model with e-health literacy to explain patients’ motivations for signing digital medical consent forms. The subjects of this study were Taiwanese citizens over 20 years of age. A total of 300 questionnaires were distributed, of which 296 valid questionnaires were received, resulting in a 98.67% response rate. Structural equation modeling was used to examine the data. The results indicate that attitude, perceived behavioral control, and e-health literacy have positive effects on signing intention, whereas the subjective norm does not significantly affect it. Furthermore, self-efficacy is affected by e-health literacy. This study has implications for the development of strategies aimed at increasing the signing of digital medical consent forms.