It was a Group G clash that the Hoops were not supposed to win but the East End of Glasgow exploded as Victor Wanyama and Tony Watt scored leaving Lionel Messi's late strike a consolation and pop singer and Celtic fan Rod Stewart crying in the stands after the final whistle.
Hoops boss Lennon, though, could hardly suppress his joy, saying: "I think it was one of the greatest nights in the club's recent history."
He continued: "It was very poignant at our 125th anniversary, one to play Barcelona in such a prestigious game and two, to win the game under huge difficulties with the squad decimated by injuries and illness.
"The players are heroes, they are heroes to me, I can't speak highly enough of their performance tonight and they will go down in the history books of the club as the team who beat probably the best team in the world.
"Everyone goes on about tactics but football is about players and they have covered themselves in glory tonight."
Celtic, with seven points from four games, two less than leaders Barca, travel to Benfica before hosting Spartak Moscow in their final group fixture. Benfica have four points following their home win over Spartak Moscow, who are bottom of the group with three points.
The Hoops fans will surely fancy their side's chances of reaching the knockout stages of the competition but Lennon remained cautious.
The former Celtic skipper said: "We have a chance, that's all it has given us. A greater chance than maybe we expected before the game.
"But we still have two very tough games. The problem is the players and staff will have to deal with is that the expectation level will increase. There is still a lot of work to do but we have given ourselves a platform. But that's for the future, I want the players to enjoy the moment and take it all in."
- Sports & Recreation