This study aimed to elucidate the formation of adolescents’ communicative lifeworld within social media environments and to conceptualize their cultural and social experiences, together with the tensions arising from the intersection of these experiences. The study adopted a qualitative approach and employed thematic analysis. The research was conducted in Tehran and Karaj and involved 23 adolescents aged 15–18, selected through purposive maximum-variation sampling. Data were collected in the Iranian year 2026 through semi-structured interviews lasting 45–60 minutes and were analyzed in accordance with Braun and Clarke’s six-phase analytical process. The trustworthiness of the findings was assessed using Lincoln and Guba’s criteria of credibility, transferability, dependability, and confirmability. The findings indicated that adolescents’ communicative lifeworld constitutes an extension of their everyday lives, within which peer relationships, belonging, self-presentation, privacy, cultural learning, and platform logic are closely intertwined. Cultural experiences were manifested in the recombination of local and global resources, reflexive identity formation, content production, and linguistic transformation, whereas social experiences were reflected in the reconfiguration of relationships, support, trust, family negotiation, and vulnerability to exclusion. Rather than remaining passive in the face of networked pressures, adolescents exercised communicative agency by regulating audiences, engaging in selective self-disclosure, negotiating relationships, adopting critical distance, and recalibrating their online presence. Accordingly, the concept of the communicative lifeworld offers an integrated framework for understanding culture, relationships, agency, and platform logic within the experience of adolescence.