This study investigated whether online communication among learners from different cultural backgrounds mediates Iranian EFL learners’ intercultural sensitivity (IS) development. To this end, two experimental and one control groups, and a group of intercultural speakers participated in the study. Each Iranian group consisted of 15 EFL learners who were university students majoring in English language and Literature at upper-intermediate and advanced levels of proficiency. The intercultural group consisted of 4 non-native English speakers of differing cultural backgrounds. The first experimental group engaged in intercultural discussions with intercultural speakers, while the second experimental group took part in in-person cultural discussions with their peers. Learners in the control group discussed general topics with their peers. Intercultural Sensitivity Scale (ISS) was used to evaluate IS of the participants prior and after the completion of the study. Findings revealed the outperformance of the first experimental group in IS. However, no significant difference was found between the control and second experimental groups in their interaction engagement, interaction confidence, and interaction attentiveness. Implications of the study are discussed in the paper.