Bayern claimed the title with a 3-1 win at Hertha Berlin.
The Bavarian giants broke their own record for the earliest confirmed league title win, set last April under Jupp Heynckes en route to the treble of European, league and cup titles, by one match.
"We won the title with hard work and when you see what Jupp Heynckes achieved last season, that was the only way we were going to better that," said Guardiola. "He laid the foundations."
Bayern star Thiago Alcantara posted this photo of the post-match celebrations on Twitter.
In his debut season, Guardiola has now won three titles in nine months after last August's UEFA Super Cup triumph and December's Club World Cup success having won 14 titles in four years at Barcelona.
"Obviously I'm delighted that we have retained the title," said Guardiola as his side opened up an unassailable 25-point lead over second-placed Borussia Dortmund.
"I want to thank my players and the club who have helped me achieve this. We had a lot of injuries in recent months and we have not always played well, but my players showed character.
"Tonight we were very active from the start, but in the second half we lost a little of our control. I am just happy we have finally managed it. It didn't matter when we got it just as long as we won the title for this great club. We'll celebrate today and tomorrow."
Bayern's 19th consecutive Bundesliga win also extends their record unbeaten league run to 52 matches.
They are still on course to become the first side to finish a Bundesliga season unbeaten.
"It's unbelievable to clinch the title on the back of an unbeaten record," said winger Arjen Robben. "We're all unbelievably proud of the team and our achievements this season."
Midfielder Toni Kroos slammed home an early strike before Mario Götze headed their second as Bayern went 2-0 up after 14 minutes.
Hertha's Colombia striker Adrian Ramos converted a second-half penalty before France winger Franck Ribery came off the bench to net a superb third 11 minutes from time.
It is now mathematically certain that Bayern cannot be caught by their rivals, although in truth the title race has been over for weeks.
Germany midfielder Bastian Schweinsteiger, who has won the Bundesliga title for the seventh time in his career, said the players would party long into the Berlin night.
"I've given the assistant coaches a few tips, but we'll definitely enjoy the party tonight, wherever it is," said the 29-year-old.
Germany coach Joachim Löw, who was in the stadium, said Bayern's success could only help the national team during June's World Cup in Brazil.
"To win the title so early is an incredible achievement," said Löw. "Pep Guardiola has developed the team and made his mark in terms of dominance and possession. "Bayern have a mentality that demands unconditional success."
Jurgen Klopp, coach of rivals Borussia Dortmund offered Guardiola his congratulations.
"It's unbelievable the way you have torn things up down there," said Klopp, whose second-placed side were held to a goalless draw at home to Schalke in the Ruhr derby. "You're so far ahead, we'd need a telescope to see you.
"It's a fantastic achievement."