This mixed-methods study investigates the development of intercultural communicative competence (ICC) among Bangladeshi university students through the creation of online advertisements for products like tea, kettles, and mango drinks. Grounded in the frameworks of Ertay and Gilanlioglu’s multidimensional ICC scale, Kress and van Leeuwen’s social semiotics, and Dooly’s asynchronous interculturality, the research examines how student-made ads serve as cultural texts that manifest evolving ICC. Quantitative results from 90 participants revealed significant disparities in self-assessed ICC, with Attitude scoring highest (71%) and Awareness lowest (54%). Longitudinal analysis of 60 students showed Language Appropriateness improved most (37%, p  < 0.01), while Visual Cultural Cues showed minimal gains (18%, p  = 0.08), indicating a cultural bias in visual literacy development. Pedagogically, advertisement creation supported by a structured ICC rubric yielded significantly higher competence gains (29%) than case studies or ad creation alone. Qualitative findings illuminated the challenges students faced in negotiating “glocal” identities and the emotional labor of cultural mediation. The study concludes that student-generated advertisements are potent pedagogical artifacts for ICC development but require tailored, critically reflective scaffolding to address contextual biases and effectively prepare students for the demands of global digital business communication.