Background: Most cerebral gray matter studies investigating suicidality in depression have used voxel-based morphometry analyses. This study aims to investigate cortical morphology alterations to provide more detailed insight into gray matter structure and to obtain evidence for neuroanatomical alterations in the suicidal brain. Method: We performed a surface-based morphometry analysis to estimate the complexity of cortical folding (fractal dimension, FD), sulcal depth (SD) and cortical thickness (CT) in 39 healthy controls (HC), 40 depressed patients without suicidality (PC) and 39 with suicidality (SU) using the Computational Anatomy Toolbox (CAT12). Then, we performed correlation analyses between clinical data and the cortical surface measurements in patients. Findings: We found compared to both the HC and PC groups, the SU group showed significantly decreased SD in the frontal, limbic, parietal, temporal, and occipital regions and decreased FD in the frontal regions. In both the PC and SU groups, a significant negative correlation was found between the SD of the left caudal anterior cingulate cortex and Hamilton Depression Rating Scale (HAMD) scores. Interpretation: Abnormal cortical morphology in the default mode network, frontolimbic circuitry and temporal regions are implicated in MDD patients with suicidality. These structural deficits may represent a neurobiological endophenotype related to suicidality in MDD patients, which may be related to reported deficits in emotional processing and impulsivity control. Funding Statement: This study was supported by National Natural Science Foundation (Nos.81971595, 81771812, 81761128023, 81621003 and 81801681), PCSIRT (No.IRT16R52), Science and Technology Department of Sichuan (2018SZ0391) and Innovation Spark Project of Sichuan University (2019SCUH0003). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: This study was approved by the Ethics Committee of West China Hospital, Sichuan University, and all subjects provided written informed consent.