The aim of this study was the investigation of the impact of a year-long, student-centered Physical Education (PE) project, in which mobile applications for Physical Activity (PA) and nutrition monitoring, exergames and an online social learning platform were utilized, on students' PA, sedentary behavior and food selection criteria. The study followed a pretest/posttest design involving 51 students (aged 15-16 years), split into two groups: the experimental group (n = 25), that participated in the project in parallel with attending the regular PE course, and the control group (n = 26), that only attended the regular PE course. The project lasted 7 months, two of which coincided with a quarantine because of COVID-19, during which, all project activities were coordinated through the online platform. The analysis of the data, which were collected through questionnaires, showed an increase in the experimental group students' use of mobile devices for PA and nutrition monitoring as well as a greater improvement of their perceived helpfulness of PA applications and food selection criteria, in relation to the control group. The quarantine did not significantly affect their levels of PA and sedentary behavior, although, in the control group, PA decreased significantly and sedentary time increased significantly. The students were highly satisfied with the project.