We evaluated the effects of mental health interventions among people hospitalized with COVID-19. We conducted a systematic review and searched 9 databases (2 Chinese-language) from December 31, 2019 to June 28, 2021. Eligible randomized controlled trials assessed interventions among hospitalized COVID-19 patients that targeted mental health symptoms. Due to the poor quality of trials, we sought to verify accuracy of trial reports including results. We identified 47 randomized controlled trials from China (N = 42), Iran (N = 4) and Turkey (N = 1) of which 21 tested the efficacy of psychological interventions, 5 physical and breathing exercises, and 21 a combination of interventions. Trial information could only be verified for 3 trials of psychological interventions (cognitive behavioral, guided imagery, multicomponent online), and these were the only trials with low risk of bias on at least 4 of 7 domains. Results could not be pooled or interpreted with confidence due to the degree of poor reporting and trial quality, the frequency of what were deemed implausibly large effects, and heterogeneity. Trials of interventions to address mental health in hospitalized COVID-19 patients, collectively, are not of sufficient quality to inform practice. Health care providers should refer to existing expert recommendations and standard hospital-based practices. Registration: PROSPERO (CRD42020179703); registered on April 17, 2020.