The purpose of this study was to design and validate an assessment tool to find out how primary school students perceive their competency-based learning. By examining the content validity (n = 35 experts), comprehension (n = 173 students) and construct (n = 523 students) of the instrument, the results showed correct psychometric quality, internal consistency, reliability and adequacy of the structural model: X-2/df = 2.08, TLI = 0.88, CFI = 0.90, GFI = 0.90, RMSEA = 0.04, and SRMR = 0.04. The final version of the Questionnaire on Perceived Competency-based Learning of primary school students (#ICOMpri1) includes eight dimensions and 27 items. The results showed a high perceived competency-based learning of primary school students. This is therefore a valid and reliable instrument that provides a more subjective and real vision of primary students' academic performance. Nevertheless, future studies should analyse the criterion-related validity by comparing perception results with those of international academic achievement.