Informed by the dimensional approach to adversity, this study disaggregated child maltreatment effects to examine how abuse versus neglect influenced cortisol at the baseline assessment and longitudinal changes in diurnal cortisol among a sample of Chinese children and adolescents (N = 312; aged 9–13 years; Mage = 10.80, SD = 0.84; 67% boys). The moderating roles of resilience and sex differences in these associations were also explored. Results revealed distinct effects of abuse versus neglect on diurnal cortisol in girls, but not boys, which varied by the time scale of assessment and type of cortisol measure. Specifically, abuse was associated with girls’ longitudinal changes in awakening cortisol, cortisol awakening response, and diurnal cortisol slope over one year, whereas neglect was associated with girls’ awakening cortisol and cortisol awakening response at the baseline assessment. Further, resilience moderated the effects of abuse on girls’ baseline awakening cortisol and longitudinal changes in diurnal cortisol slope, suggesting both the potential benefits and costs of resilience. Findings support the application of the dimensional approach to research on stress physiology and deepen our understanding of individual differences in the associations between child maltreatment and diurnal cortisol.