Activity trackers (ATs) equipped with biometric sensors may support deep knowledge acquisition of health and active learning. The mechanism may be via personal data being pushed to the students, which deepens the knowledge about their own health and may impact long-term health action processes. To understand health knowledge acquisition, 43 students attending an undergraduate university course were equipped with an AT over a period of five months. Weekly observation on emerging personal data and consequent actions (lifestyle adaptations) were reflected in an individual course-related ePortfolio. Students' change in health action process was assessed using a short standard eHealth literacy scale at the beginning and end of the course. The usability of ePortfolio tool was tested with two previously validated scales. The combination of personal information from an AT and ePortfolio may have enhanced students' critical assessment of health-related personal and available digital information. eHealth literacy scores significantly increased by the end of the course (p < 0.01). The ePortfolio helped with learning, and the usability of the ePortfolio did not really interfere. The combination of AT and ePortfolio constitutes a novel and productive method of using ePortfolios in higher education in regards to eHealth literacy acquisition.