Procrastination is a maladaptive behavior associated with a wide range of negative life outcomes, such as poorer educational and occupational performance, and lower levels of physical and mental health. Although previous research has demonstrated that individuals with heightened future time perspective (FTP) exhibit reduced procrastination, the cognitive and neural bases of this relationship remain unclear. Drawing on the self-regulatory framework of time perspective, the present study used two large independent samples (N = 447, N = 459) to test whether self-control and its underlying neural substrates mediate the relationship between FTP and procrastination. Participants were recruited to undergo resting-state functional magnetic resonance imaging and complete questionnaires assessing FTP, procrastination, and self-control. Behavioral results from both samples indicated that self-control partially mediated the association between FTP and procrastination. Whole-brain correlation analysis in Sample 1 further revealed that self-control was associated with greater amplitude of low-frequency fluctuations in the left dorsolateral prefrontal cortex (DLPFC). Notably, amplitude of low-frequency fluctuations in the left DLPFC was also found to mediate the FTP-procrastination relationship in both samples. The current study provides considerable evidence that spontaneous activity in the DLPFC, which supports self-control, serves as a neural substrate mediating the association between FTP and procrastination.