Evolutionary theory argues that dance and music have evolved as collective rituals for social bonding and signaling. Yet, neuroscientific studies of these art forms typically involve people watching video or sound recordings alone in a laboratory. Across three live performances of a dance choreography, we simultaneously measured real-time dynamics between the brains of up to 23 audience members using mobile wet-electrode EEG. Interpersonal neural synchrony (INS) in the delta band (1–4 Hz) was highest when performers directly interacted with audience members (breaking the fourth wall) and varied systematically with the dancers’ movements and artistically predicted and actual continuous engagement. In follow-up studies using video recordings of the performance, we show that audience brain synchrony and engagement are highest when dance is experienced live and together. Our study shows that the ancient social functions of the performing arts are preserved in engagement with contemporary dance.