Cognitive impairment is significant in the progression from clinical high-risk (CHR) to schizophrenia-spectrum psychosis. A study aimed to explore cognitive trajectories of CHR individuals over three years, comparing those who converted to psychosis (CHR-C), those who did not (CHR-NC), and healthy controls (HC). Participants included 43 CHR individuals and 18 HC, assessed at five time points using the Chinese version of the MATRICS Consensus Cognitive Battery. Results indicated that CHR-C individuals exhibited more severe cognitive impairments compared to CHR-NC and HC at all assessments, with the most pronounced decline occurring in the first year. Growth curve modeling revealed a significant negative impact on neurocognitive composite scores for the CHR-C group, while repeated-measures analysis of variance showed significant differences among groups and time-related changes in cognitive scores. Over the study period, the effects of time and group were highly significant. Different cognitive domains demonstrated varying change trends across groups, highlighting the first year after CHR identification as a crucial period for cognitive changes. These findings underscore the significance of early cognitive assessments in predicting psychosis and inform strategies for early intervention.