"Jacob has been dealing with leukemia and he spends a lot of time in his bedroom, so I said, 'Why not go to this boy's house and revamp, renovate and change his bedroom in one of the most massive ways possible?'" Hart told ET.
Inspired by Jacob's interest in muscle cars, Hart linked up with BrittiCares and Rally Health to give Jacob's room a race-car makeover complete with sports car wall figures and drawers made to look like tool chests.
There wasn't a dry eye in the house when Jacob tearfully thanked everyone after the epic unveiling.
"Thank you so much for all of this," Jacob said. "I just can't put it in words."
BrittiCares, with the help of Kevin Hart and Rally Health, are helping to increase the quality of life for children suffering from cancer.