His side remain in second place with only two games left in Group G after goals from Victor Wanyama and Tony Watt, the 18-year-old substitute, brought down Barcelona by 2-1. Even a very late Lionel Messi goal could not prevent Celtic from joining Real Madrid as the only clubs to beat the mighty Catalans in any competition this season.
Celtic now travel to face Benfica on November 20 before the campaign ends at home to Spartak Moscow on December 5, and Lennon has a real chance of emulating former manager Gordon Strachan by taking the club into the last 16. Barcelona should still win the group but the Scottish champions could go through with them.
Lennon was conspicuously composed and measured after the match, but his assessment was still revealing. "This is up there with anything I have done in my life," said the Celtic manager. "As a manager I don't know if I will ever top that. I hope I do, I'm still young and still learning, but that is right up there with anything I have achieved not just in my football career but in my life.
"That is one of the greatest results in the club's recent history. The players are heroes to me and I can't speak highly enough of their performance."
Watt, Charlie Mulgrew and goalkeeper Fraser Forster received individual praise, the goalkeeper producing a number of saves to help Celtic through what Lennon called a "storm" of Barcelona pressure.
"We have just played the best team in the world," he said. "The difference in the teams is that Tito [Vilanova, the Barcelona coach] can bring Cesc Fabregas and David Villa off the bench and I bring on an 18-year-old kid who cost £50,000 from a team called Airdrie. You can talk about tactics until you are blue in the face as far as I am concerned but football is about the players. They have covered themselves in glory tonight. We do prepare the team as well as we can."
Celtic had identified that a run to the back post by Wanyama, to meet a Mulgrew corner, could expose the lack of height in Barcelona's defence. So it proved at the opening goal. "We did feel there was an area where Barcelona were vulnerable from corners," he said. "Jordi Alba is zonal at the back post and they basically leave half of the box empty. But the delivery is so important and Charlie Mulgrew is one of the best dead-ball deliverers in British football.
"We can give them instructions but it's down to the players to go and do it, and they made it happen tonight. Tony Watt has written himself into the history books of the club. He is only 11 games into his career. I hope he has a fruitful career but what he has done tonight will take some topping.
"We have a chance of reaching the last 16. That's all it's given us: a greater chance than we maybe expected before the game. The problem that myself and the players will have to deal with now is that the expectation level will increase.
"I have to commend the supporters tonight. This is what Celtic is about, it makes the club so special. It's one of the greatest arenas in football and you saw that tonight. I hope this restores some pride for Scottish football. This is a country with a great footballing history; I hope this has given the game a huge boost."
Vilanova was questioned by the Spanish media about the lack of height in his team, which Celtic exploited. "Yes we could sign taller players but I also like to have fun on the bench and that is the way we play. This isn't the first game we have lost like this and it won't be the last. It is a really difficult stadium and we played as though we were the local team.
"I would like to give my congratulations to Celtic and to their fans who have been amazing tonight. We knew before the game that Celtic were really good at set-pieces and they are. We had many chances and you have to talk about the Celtic goalkeeper; he was brilliant tonight. Celtic play as well; it's not just about us."