Music has been identified as a strength in people with Autism Spectrum Disorder, however, there is currently no neuroscientific evidence supporting its benefits. Given its universal appeal, intrinsic reward value and ability to modify brain and behaviour, music may be a potential therapeutic aid in autism. Here, we evaluated the neurobehavioral outcomes of a music intervention, compared to a non-music control intervention, on social communication and brain connectivity in school-age children (ISRCTN26821793). Fifty-one 6-12 year olds with autism were randomized to receive 8-12 weeks of music (n=26) or non-music intervention (n=25). The music intervention involved use of improvisational approaches through song and rhythm to target social communication. The non-music control was a structurally-matched behavioural intervention implemented in a non-musical context. Groups were assessed before and after intervention on social communication and resting-state functional connectivity of fronto-temporal brain networks. Communication scores were higher in the music group post-intervention (difference score=4.84, P=.01). Associated post-intervention resting-state brain functional connectivity was greater in music versus non-music groups between auditory and subcortical regions (z=3.94, P<.0001) and auditory and fronto-motor regions (z=3.16, P<.0001). Post-intervention brain connectivity was lower between auditory and visual regions in music compared to non-music groups, known to be over-connected in autism (z=4.01, P<.00001). Post-intervention brain connectivity in the music group was related to communication improvement (z=3.57, P<.0001). This study provides the first evidence that 8-12 weeks of individual music intervention can indeed improve social communication and functional brain connectivity, lending support to further investigations of neurobiologically-motivated models of music interventions in autism.