The 'Forger' actor - who has Benjamin, as well as 15-year-old daughter Ella, with wife Kelly Preston - was unsure whether the little boy was aware of his fame until recently and the youngster is now keen to work with him in the future.
John said: "I took him to Toys 'R Us recently, and he said to me when we got out of the truck and in the cart, 'Why are all these people wanting my photograph?' Because I didn't know if he knew I was in films or not. He said, 'Well, maybe they saw one of your movies!' And he said, 'I want to work with you!' So we'll see how that evolves. I don't want to force [it]."
John - whose eldest son Jett, 16, tragically died in 2009 - loves spending time with his kids and Benjamin particularly enjoys going for rides in the 61-year-old star's new truck.
He told talk show host David Letterman: "He loves trucks. For the first time in my life, I bought a red Dodge Ram pick-up truck, a big one, and he loves it -- Ella loves it. I take him for rides."
With Benjamin expressing a desire to join his parents in the e acting world, his famous father offered him a taste of the spotlight while on the show.
However, when Kelly carried the little boy to the front and he was about to step onto the set, he got nervous and ran away.
Though both John and David tried to coax him out onto the stage, Benjamin just ran back to his mother's arms and refused to join them.