Objective Although suicide behavior is relevant in first-episode psychosis (FEP), little is known about suicidal ideation and its longitudinal stability. The aim of this study was (1) to assess incidence rates of suicide attempts, completed suicide, and suicidal thinking in FEP individuals at baseline and over a 24-month follow-up period; (2) to explore any significant association of suicidal ideation with psychopathology at baseline; and (3) to monitor longitudinally suicidal thinking along the 2-year follow-up. Methods Participants (134 FEP patients, aged 13–54 years) were assessed with the Brief Psychiatric Rating Scale (BPRS) and the Positive and Negative Syndrome Scale (PANSS). A Kaplan–Meier survival analysis to calculate cumulative incidence rates of attempted and completed suicide was also performed. Results FEP patients showed a 31.3% percentage of suicidal ideation (i.e., BPRS item 4 cutoff score of ≥ 3) and a 2-year cumulative incidence rate of attempted suicide of 11%. No completed suicide was found. In the FEP total sample, suicidal thinking was positively correlated with general psychopathology (especially depression) and negative symptoms. Conclusions Suicidal ideation is relevant in FEP patients, supporting a routine monitoring of suicide risk during the baseline assessment of adolescents and adults with early psychosis.