The "Good Will Hunting" star was the headliner at a benefit at the Yamashiro Farmers Market, held to raise funds for beloved local children's entertainer Ellen 'Twinkles' Meyers, who suffered a severe stroke last year, reported Contactmusic.
But it was Driver's son Henry who stole the show as the four-year-old drew loud cheers after joining his mother for a rendition of The Killers' single 'Human'.
In video footage of their performance, Driver was seen holding the microphone up for little Henry, who pulled it away and continued to sing solo even after the track finished.
"My son just started piano lessons and we play the guitar together. He is clearly loving music. I was on tour when I was pregnant with him, between my seventh and eighth month, and he had a guitar pressed up against his head every night for two hours, rocking out, so he didn't have any choice! It's literally in him," she had said.