Prostate cancer (PCa) survivors frequently experience enduring psychosexual challenges following treatment, including sexual dysfunction, emotional distress, and reduced quality of life. Despite these difficulties, access to tailored support remains limited, highlighting the need for scalable and accessible alternatives such as digital interventions. This study presents the protocol for a randomized controlled trial (RCT) evaluating the effectiveness of E-Mergir, a digital psychosexual intervention developed for PCa survivors. Grounded in cognitive behavioral therapy (CBT) and mindfulness strategies, the intervention aims to enhance both sexual and mental well-being. The trial employs a wait-list control design with randomized allocation. Participants will complete assessments at baseline, post-intervention, and follow-up, using validated measures related to sexual outcomes (sexual satisfaction, pleasure, function, distress, and beliefs) and mental health outcomes (quality of life, anxiety, depression, mindfulness, relationship satisfaction, and automatic thoughts). The study aims to determine whether E-Mergir is an effective digital intervention for improving psychosexual outcomes in PCa survivors, compared to a wait-list control group. It also aims to examine treatment predictors to illustrate the mechanisms through which improvements in mental and sexual health are achieved. If effective, E-Mergir could address a critical gap in supportive care for PCa survivors and serve as a model for culturally tailored digital psychosexual interventions globally.