This study explored the effectiveness of using English sitcoms to enhance vocabulary learning among non-English major university students at Nguyen Tat Thanh University. Adopting a mixed-methods approach, including a pre-test and post-test, questionnaires, classroom observations, and semi-structured interviews, the research involved 220 participants at B1 level. The test results revealed significant vocabulary gains in the experimental group compared to the control group, with a mean of 74.2 compared to the control group’s mean of 63.1. Questionnaires also showed that students responded positively to the use of sitcoms in the classroom. Interviews provided a deep insight into teachers’ perceptions on using films as teaching tools and discovered limitations of sitcom-based vocabulary instructions. The study concludes that sitcoms are highly effective and engaging resources for vocabulary instruction when thoughtfully integrated into language curricula.