The study investigated how synchrony, or coordination of movements, affects social cognition and theory of mind (ToM) during online encounters between strangers. 126 young adults were randomly assigned to conditions with synchronized movement, unsynchronized movement, or casual conversation. Findings showed that synchronized movement increased feelings of social affiliation and improved ToM performance, but did not impact empathy. The results suggest that synchrony can foster some socio-cognitive abilities even in online interactions between unfamiliar individuals.