Numeracy skills are integral to the National Assessment, serving as a benchmark for gauging learning success. In addition to cognitive aspects, the affective aspect crucial in learning is self-efficacy. However, according to PISA 2018 data, the average score for numeracy skills of Indonesian students ranks in the bottom 6. The existing condition of students does not reflect optimal self-efficacy. This reality stems from the lack of meaningful application of the learning model. Consequently, there is a need for a student-centered learning approach, such as the project-based learning (PjBL) model. This study aimed to assess the enhancement of students' numeracy skills and mathematical self-efficacy when taught using the PjBL model. Employing an experimental design with a pretest-posttest control group, the research sample comprises two groups: experimental (PjBL) and control (conventional), each consisting of 50 students. Data collection involved tests and questionnaires, with the numeracy test and self-efficacy questionnaire serving as research instruments. The ANOVA test was applied for data analysis. The results indicate that (1) students' numeracy skills, when exposed to the PjBL model, surpass those of students undergoing conventional learning; (2) students' self-efficacy, influenced by the PjBL model, is superior to that of students engaged in conventional learning.