Primary care providers (PCPs) are increasingly called upon to screen for and treat depression. However, PCPs often lack the training to diagnose and treat depression. We designed an innovative 12-month evidence and mentorship-based primary care psychiatric training program entitled the University of California, Irvine (UCI) School of Medicine Train New Trainers Primary Care Psychiatry (TNT PCP) Fellowship and examined whether this training impacted clinician prescription rates for antidepressants. We retrieved information on 18,844 patients and 192 PCPs from a publicly insured health program in Southern California receiving care between 2017 and 2021. Of the 192 PCPs, 42 received TNT training and 150 did not. We considered a patient as exposed to the providers TNT treatment if they received care from a provider after the provider completed the 1-year fellowship. We utilized the number of antidepressant prescriptions per patient, per quarter-year as the dependent variable. Linear regression models controlled for provider characteristics and time trends. Robustness checks included clustering patients by provider identification. After PCPs completed TNT training, exposed patients received 0.154 more antidepressant prescriptions per quarter-year relative to expected levels (p < 0.01). Clustering of standard errors by provider characteristics reduced precision of the estimate (p < 0.10) but the direction and magnitude of the results were unchanged. Early results from the UCI TNT PCP Fellowship demonstrate enhanced antidepressant prescription behavior in PCPs who have undergone TNT training. A novel, and relatively low-cost, clinician training program holds the potential to empower PCPs to optimally deliver depression treatment.