The 16-year-old came on to replace Oliver Burke at the start of the second half, as a brace from fellow youngster Michael Johnston helped the Bhoys record a 2-1 win in their final Scottish Premiership game of the season.
Speaking to BBC Sport, Lennon said that he had “no hesitation” about giving Dembele game time.
“He is the type of player that you want at Celtic,” the manager said. “He gets the crowd off their feet with his football intelligence. Obviously we need to keep a lid on it, but it’s great that the fans have seen the glimpse of the future.
“The kid is 16 and we just want to develop him in the right way. He has been training with the first team and I had no hesitation giving him 45 minutes.”