Emotional mental imagery is a powerful part of our mental landscape. Given its capacity to depict, process, and generate emotional events, mental imagery could have an important role in psychological therapies. This Series paper explores whether harnessing emotional mental imagery is meaningful to young people; ways in which interventions use emotional mental imagery; contextual and individual factors influencing intervention effectiveness; and mechanisms underpinning imagery techniques. We completed a systematic review of imagery interventions and consulted young people with lived experience (n=10) and leading international experts (n=7). The systematic search identified 86 papers covering a diverse range of imagery interventions. Across the seven categories of techniques reviewed, imagery rescripting for aversive memories, techniques targeting positive imagery, and imagery-enhanced protocols indicated the most potential. The report suggests that harnessing emotional mental imagery in psychological interventions could be a promising approach to reduce anxiety and depression and that mental health science could inform the development of new interventions and help to maximise intervention effectiveness.