Background Cognitive dysfunction is one of the most prominent characteristics of psychiatric disorders. At present, the neural correlates of cognitive dysfunction across psychiatric disorders are poorly understood. The aim of this study was to investigate functional connectivity and structural perturbations across psychiatric diagnoses in three neurocognitive networks of interest, including the default-mode (DMN), the frontoparietal (FPN) and the salience network (SN). Methods We performed meta-analyses of resting-state functional MRI (R-fMRI) whole-brain seed-based functional connectivity in 8,298 patients (involving 8 disorders) and 8,165 healthy controls and a voxel-based morphometry analysis of structural MRI data in 14,027 patients (involving 8 disorders) and healthy 14,504 controls. To aid the interpretation of the results, we examined neurocognitive function in 776 healthy participants from the Human Connectome Project. Results We found that the three neurocognitive networks of interest were characterized by shared alterations of functional connectivity architecture across psychiatric disorders. More specifically, hypoconnectivity was expressed between the DMN and ventral SN and between the SN and FPN, whereas hyperconnectivity was evident between the DMN and FPN and between the DMN and dorsal SN. This pattern of network alterations was associated with gray matter reductions in patients, and was localized in regions that subserve general cognitive performance. Conclusions This study is the first to provide meta-analytic evidence of common alterations of functional connectivity within and between neurocognitive networks. The findings suggest a shared mechanism of network interactions that may associate with the generalized cognitive deficits observed in psychiatric disorders.