This study describes the effectiveness of using Quizizz in fundamental physics online learning activities regarding learning outcomes and student responses. The research was conducted at Musamus University in the odd semester 2020/2021 academic year. This type of research used a mixed method. The subjects in this study were 59 students who took fundamental physics courses. The instruments used in this study were multiple-choice questions, student response questionnaires, and interview guide sheets. This study indicates that the percentage of students’ complete learning outcomes in fundamental physics courses is 79,24%. In addition, 14.3% of students said they strongly agree that Quizizz is effective in learning, and 85.7% say that they agree. The learning outcomes obtained are also supported by interviews, which state that students are pleased and motivated in participating in fundamental physics learning. Because learning basic physics using Quizizz makes them feel that learning is exciting and increases their interest in listening to basic physics learning materials. Thus, it can be concluded that the use of Quizizz in learning Basic Physics in the era of the Covid-19 pandemic has very high effectiveness.