The aim of this study is to test the effectiveness of the flipped classroom method in improving the critical thinking skills of senior high school students in Islamic history. The study utilized a quasi-experimental design with a control group and pre- and post-testing. Participants included 68 eleventh-grade students from Hasmi Islamic High School in Bogor, divided into two groups: an experimental group (34 students) that utilized the flipped classroom method (using video tutorials for independent learning at home and in-depth discussions in class), and a control group (34 students) that utilized traditional methods. Data were collected using a validated critical thinking test based on the Facione dimensions (interpretation, analysis, evaluation, inference, explanation, and self-regulation), participant observation, and in-depth interviews. Data analysis utilized an independent t-test and N-Gain analysis to measure improvement. The results showed that the experimental group demonstrated a significant improvement in critical thinking skills (N-Gain 0.68; high category) compared to the control group (N-Gain 0.32; medium category), with a significance level of p < 0.001. Key findings indicate that the flipped classroom effectively improves students' skills in analyzing Islamic historical sources, evaluating historical arguments, and drawing contextual conclusions, as well as increasing their independence and active engagement in learning Islamic history. This approach has the potential to become an innovative teaching alternative for developing critical thinking in subjects related to the history of religion.