Prospective memory (PM) is the ability to remember to carry out future intentions when prompted by a cue, and previous studies have suggested that emotional PM cues may enhance PM performance. This study examined the influence of emotional cues on PM performance in patients with schizophrenia and major depressive disorder. All participants were required to respond to emotional or neutral PM cues while completing a working memory task. Healthy participants showed improved PM performance with positive and negative cues. Patients with major depressive disorder were not impaired in PM performance and showed significant improvement in PM performance when cued by negative but not positive cues. Patients with schizophrenia had impaired PM performance irrespective of cue emotionality. In addition, the majority of patients with schizophrenia failed to show an emotional enhancement effect, and only those who had normal arousal ratings for negative PM cues showed emotional enhancement effect. These findings show for the first time that patients with schizophrenia exhibit PM impairments even with emotional cues, and suggest that arousal may be a critical factor for schizophrenia patients to utilize emotional cues to facilitate execution of future actions. In patients with major depressive disorder, our findings suggest that the negative bias in attention and retrospective memory may also extend to memory for future actions. These novel findings have both theoretical and clinical implications.