IntroductionProstate cancer (PCa), as a malignant tumour with rapid development in recent years, significantly affects men’s health, work, life and economy. Androgen deprivation therapy (ADT) plays an important role in the treatment of PCa and can be used as a complementary therapy in the late stage of castration-resistant prostate cancer. Though ADT targeting PCa shows an effective therapeutic effect, the underlying side effects (cognitive disorder, hot flashes, a decrease in sexuality) cannot be ignored. At present, cognitive behavioural therapy (CBT) has been widely used for patients with PCa after ADT due to its confirmed efficacy, fewer side effects and lower economic burden. However, the effectiveness of CBT for patients with PCa after ADT is still controversial. Therefore, we will conduct a systematic review and meta-analysis of the effectiveness of CBT for patients with PCa after ADT.Methods and analysisLiteratures will be searched from establishment of the database to 31 May 2021 with the language restrictions of English and Chinese in eight online databases (PubMed, Embase, the Web of Science, Cochrane Library, VIP, CNKI, CBM, and WAN FANG). This study will include RCTs that performed CBT as the main method of the experimental group for patients with PCa after ADT. Two or more reviewers will independently conduct the selection of studies, data extraction and data analysis. The risk ratios with 95% CIs will be used to present the data synthesis result of dichotomous data, while weighted mean differences or standardised mean differences with 95% CIs will be used to present the data synthesis result of continuous data. Meanwhile, evidence quality of outcome will be assessed by using the Grading of Recommendations Assessment, Development and Evaluation method. Stata V.13.0 and Review Manager software V.5.3 will be used for analysis and synthesis.Ethics and disseminationThis protocol is a second study based on a completed randomised controlled study. Thus, ethical approval is not required, and no additional data are available.OSF registration numberDOI 10.17605/OSF.IO/FUVEA