Anthony Stokes headed the visitors into the lead in the third minute before 17-year-old substitute Liam Henderson, on for right-back Adam Matthews at the start of the second-half, opened his Celtic account in the 49th minute with a low drive from 12 yards.
Norwegian midfielder Stefan Johansen added a third in the 53rd minute to confirm the superiority of the visitors, who responded to losing a late goal to Thistle substitute Christie Elliott by scoring another two through Stokes and Kris Commons.
It secured a third successive title for Celtic and afterwards the manager said: "They finished it with the way we want them to play. In the second half some of the football was breathtaking. You could feel it over the last couple of weeks, the anticipation building and the style in which we finished it was fantastic, symptomatic of the way this team is.
"This title win is better. The next one is always better. This has been the most consistent in the league, although the cups were disappointing this season. But certainly the league form was magnificent. To lose one game and break a clean sheet record into the bargain, it has been an exceptional."
The former Celtic captain put the pitch invasion at the end of the match down to "a little bit of over-exuberance", even though it prevented the players coming out afterwards to take a bow.
Lennon said: "Our support tonight was magnificent. Some of the fans have never experienced the championship-winning run that we have had in the last nine or 10 years. We want to reach out to a younger generation and hope they come along for a lifetime, that is really important and I think they can all be really proud of the team and the club tonight.
"They are seeing Celtic dominate Scottish football and some of the older ones haven't seen these heady days for a long long time. Since Martin O'Neill came in in 2000, it has been superb, Gordon Strachan took over and I am just following on in that tradition. It is a great moment for me but it is all about the team, I have a great network behind me with the board and backroom team and I am just the front.
"We are seeing the evolution of a another team. It is not just about domestic success, we strive to be a successful Champions League side which is important.
"We have had two campaigns and we will do everything we can to have a third one and I will look to improve on the cup competitions but in terms of the league I couldn't ask for any more from the players."
Henderson, who scored his first Celtic goal with a right-footed drive in only his fourth first-team appearance, admitted he did not see his strike go in.
He said: "I am really happy by scoring the goal but it is the boys have done it from the very start, they have won the league and I have just been very fortunate that I have been given a run of games.
"Obviously I managed to get a goal and I am very happy with that. But I didn't even see it go in. I was away celebrating before it went in. It was an unbelievable feeling and it still hasn't sunk in yet, it will take a few days."
Alan Archibald, the Thistle manager, will try to forget the thumping defeat as his 10th-placed side try to stay away from the relegation play-off spot with a trip to St Johnstone next on the agenda.
He said: "I will chat to the lads tomorrow about the game but the main focus is on Saturday. Celtic started really positively and they went after us. We gave them that goal and they took the wind out of our sails. They did the same in the second-half and it is hard to play against a team in that form.
"But we have only had to play Celtic three times in a season and no disrespect to St Johnstone, Celtic are totally different altogether. You seen that in the second half, Commons, Stokes and Leigh Griffiths are a real problem for anybody. We have seven games which are seven cup finals."