Although problem-based learning (PBL) approach in L2 classrooms might enhance students' critical thinking and creativity while contributing to their language development, its role in these classrooms has not been fully explored. Therefore, adopting a mixed method approach, this study aimed at exploring the changes in 68 Turkish tertiary-level EFL students' critical thinking and creativity in addition to their language abilities before and after participating in a PBL program. Convenience sampling was used in the research and students were sampled simply because they were convenient sources of data. Quantitative data gathered through the 21st century skills scale and pre and post language tests were analyzed through both descriptive and inferential analysis for comparison. Since the data were normally distributed, a paired t-test was conducted to compare the scores for the language achievement tests and the scales. The qualitative data gathered through an open-ended questionnaire were analyzed through a constant comparative data analysis method. The researchers coded the qualitative data set by identifying categories, patterns and codes. The findings indicated a statistically significant increase in students' level of critical thinking and creativity and improvement in their language scores. Hence, this paper might provide a model for English teachers to integrate PBL in their classrooms to promote their students' language skills as well as their critical thinking and creativity.