BACKGROUND: To explore changes in regional homogeneity (ReHo) of brain function in patients with Parkinson's disease with mild cognitive impairment (PD-MCI) using resting-state functional magnetic resonance imaging (rs-fMRI), and to analyze the correlation between ReHo values in differential brain regions and cognitive function, so as to identify potential neuroimaging biomarkers for PD-MCI. METHODS: A total of 43 patients with PD were enrolled and divided into the PD-MCI group (n = 23) and the PD with normal cognitive function (PD-NC) group (n = 20). Additionally, 20 healthy controls (HC) were recruited. The ReHo method was used to evaluate differences in functional consistency of brain regions, and the Montreal Cognitive Assessment (MoCA) scale was employed to assess cognitive function. Further, a correlation analysis was performed between the ReHo values of each brain region and MoCA scores in patients with PD-MCI and PD-NC and the receiver operating characteristic (ROC) curve was used to evaluate the discriminative efficacy of these brain regions for PD-MCI. RESULTS: Compared with the PD-NC group, the PD-MCI group showed significantly decreased ReHo values in the right middle frontal gyrus and right superior frontal gyrus (t = -3.3113, -4.1326, both p < 0.05), and significantly increased ReHo values in the right cerebellar lobule VIII, left inferior temporal gyrus, and right fusiform gyrus (t = 4.9059, 2.9759, both p < 0.05). MoCA scores were negatively correlated with ReHo values in the right cerebellar lobule VIII, left inferior temporal gyrus, and right fusiform gyrus (r = -0.5597, -0.6239, p < 0.05), and positively correlated with ReHo values in the right middle frontal gyrus and right superior frontal gyrus (r = 0.5690, 0.5296, p < 0.05). ROC analysis showed that the ReHo values of the right cerebellar area VIII and the left inferior temporal gyrus had high efficacy in distinguishing PD-MCI from PD-NC, with an area under the curve (AUC) of 0.9326. CONCLUSION: Functional abnormalities in brain regions including the right middle frontal gyrus, right superior frontal gyrus, right cerebellar lobule VIII, left inferior temporal gyrus, and right fusiform gyrus are closely associated with the occurrence and development of PD-MCI. ReHo indicators in these regions are promising potential neuroimaging biomarkers for auxiliary diagnosis and monitoring the progression of PD-MCI.