Heart rate variability has received growing attention in the depression literature, with several recent meta-analyses indicating that lower resting heart rate variability is associated with depression. However, the role of fluctuations in heart rate variability (or reactivity) in response to stress in depression remains less clear. The present review provides a systematic examination of the literature on heart rate variability reactivity to a laboratory-induced stressor task and depression, including 26 studies of reactivity in heart rate variability and clinical depression, remitted (or history of) depression, and subthreshold depression (or symptom-level depression) among adults, adolescents, and children. In addition to reviewing the findings of these studies, methodological considerations and conceptual gaps in the literature are addressed. We conclude by highlighting the importance of investigating the potential transactional relationship between heart rate variability reactivity and depression and possible mechanisms underlying this relationship. •Blunted reactivity of HRV may be associated with current depression in adults.•Further testing is needed for HRV reactivity among youth and adults with subthreshold and remitted depression.•Studies indicate the importance of contextual factors in the HRV reactivity- depression link.•Further research is needed to examine development, sex and curvilinear patterns.•Transactional Model of HRV Reactivity to Stress and Depression is proposed.