Georgios Samaras's last-gasp header gave the Hoops their first win away from home in the group stages of European football's elite club competition and it was a deserved victory for the Parkhead men.
"I am probably the proudest man in Europe tonight," said Lennon, "I cannot speak highly enough of the players, they were magnificent.
"They played magnificent football at a very tough venue against an excellent side.
"They showed great character and fortitude to come back after going behind just after half-time. I thought we thoroughly deserved to win it.
"We didn't start the game particularly well, we looked a bit nervous and our passing wasn't there for the first five or 10 minutes but we had a quick break and scored a good goal.
"I think people underestimate Celtic. I don't think we get the respect we deserve but maybe tonight's performance might change a few attitudes."
Celtic have four points from two games but Lennon refused to get carried away with regards their chances of qualifying for the knock-out stages.
He said: "We just have to play Barcelona home and away. It is a huge step for the club. It is our first away win in the Champions League so we have broken a record.
"It is fantastic but there is a lot of football to be played in the group. We have two home games and Benfica and Barcelona away so it is still an open group for second place as far as I am concerned.
"We are still novices in this tournament but a few more performances like that wouldn't do us any harm at all."