Background This study's purpose was to examine the predictive validity and clinical utility of a brief measure assessing youths’ own expectations of their future risk of suicidal behavior, administered in a psychiatric emergency (PE) department; and determine if youths’ ratings improve upon a clinician‐administered assessment of suicidal ideation severity. The outcome was suicide attempts up to 18 months later. Methods In this medical record review study, 340 consecutively presenting youths (ages 13–24) seeking PE services over a 7‐month period were included. Subsequent PE visits and suicide attempts were retrospectively tracked for up to 18 months. The 3‐item scale assessing patients’ perception of their own suicidal behavior risk and the clinician‐administered ideation severity scale were used routinely at the study site. Results Cox regression results showed that youths’ expectations of suicidal behavior were independently associated with increased risk of suicide attempts, even after adjusting for key covariates. Results were not moderated by sex, suicide attempt history, or age. Receiver‐operating characteristic (ROC) analyses indicated that self‐assessed expectations of risk improved the predictive accuracy of the clinician‐administered suicidal ideation measure. Conclusions Youths’ ratings indicative of lower confidence in maintaining safety uniquely predicted follow‐up attempts and provided incremental validity over and above the clinician‐administered assessment and improved its accuracy, suggesting their potential for augmenting suicide risk formulation. Assessing youths’ own perceptions of suicide risk appears to be clinically useful, feasible to implement in PE settings, and, if replicated, promising for improving identification of youth at risk for suicidal behavior.