The evaluation of the competencies corresponding to the different professional profiles of future nursing graduates is fundamental to their training. In this regard, students’ self-evaluation must be part of their training. This study aimed to develop and psychometrically test the Perceived Self-Efficacy in Nursing Competencies (PSENC) Scale. This study was conducted in two phases: selecting and adjusting items and assessing the instrument’s psychometric properties. A sample of 1416 students completed the scale online. Exploratory factor and confirmatory factor analyses were conducted. Inferential analysis was carried out. The exploratory factor analysis of the PSENC scale with 20 items resulted in five factors (76.3% of variance). All factors showed Cronbach’s alpha coefficients > 0.70. The confirmatory factor analysis measurement model showed satisfactory and adequate goodness-of-fit indices. The developed scale showed the psychometric adequacy and usefulness to the self-assessment of nursing students regarding their self-efficacy expectations in competencies during their clinical practicum. This study was not registered.