Intercultural and sociolinguistic competencies is an essential prerequisite to function effectively across cultures, to think and act appropriately, and to communicate and work with people from different socio-cultural backgrounds. Despite its significance in developing effective communicative competencies among the learners, intercultural and sociolinguistic competencies are often ignored in EFL pedagogic contexts. The current action research evaluates the impact of culture-based materials in developing and nurturing intercultural and sociolinguistic competencies among tertiary level EFL learners in Bangladesh. For the purpose of the study, the researcher designed some culture-based EFL materials and implemented them in 3 tertiary level online EFL classes. Here, semi-structured questionnaire survey, learner artifacts and teacher’s evaluation reports were used to collect data regarding the impact of these culture-based materials. The findings highlight an increase in learners’ cultural sensitivity as well as cultural awareness followed by an interest and preference for culture-based EFL materials in the teaching and learning process The findings also manifest some socio-cultural aspects, which need to be taken into account while designing and utilizing such culture-based EFL materials in the pedagogic setting of a country like Bangladesh. The study concludes by presenting some recommendations pertaining to designing and implementing culture-based materials in tertiary level EFL contexts.