Educators constantly seek innovative and engaging methods to engage students and ensure their academic achievement. Using humor in the classroom is one of the strategies which can promote classroom environment and facilitate teacher-student rapport. The purpose of the present study was to investigate the effectiveness of using humor techniques through synchronous computer-mediated communication (SCMC) in enhancing EFL teacher-student rapport. The population of this quasi-experimental study consisted of 70 Iranian female EFL intermediate learners and eight TEFL instructors. Initially, the Oxford Placement Test (OPT) was initially administered to the language learners in two English classes. Subsequently, the Questionnaire on Teacher Interaction (QTI) was administered to both teachers and students to gather their feedback. Afterward, the treatment began and lasted for twelve sessions. The control group received speaking skill instruction through traditional face-to-face teaching without humor techniques, while the experimental group received instruction incorporating humor techniques through SCMC using WhatsApp. After the treatment period, both student and teacher groups completed the QTI post-test. Upon data collection, the non-parametric Mann-Whitney U test was used to analyze potential differences in teacher-student rapport between the two independent groups at both the beginning and end of the study. The results indicated that the experimental group demonstrated a significant improvement in teacher-student rapport from both student and teacher perspectives, whereas the control group showed only minimal improvement. The results emphasize the potential of humor to serve as an effective means for fostering a positive and engaging learning environment, particularly in online or blended learning contexts.