Jurgen Klopp's side came into the match knowing a win would secure them the championship with two rounds to spare.
And they rose to the challenge, taking the lead after 23 minutes through Ivan Perisic, with Shinji Kagawa adding another in the 60th minute.
Dortmund began the day with an eight-point advantage over nearest rivals Bayern Munich, who also needed a win in their earlier kick-off to keep alive their slim title hopes.
Franck Ribery scored a last-minute winner at Werder Bremen to earn Bayern a 2-1 victory, but Dortmund's later success meant their efforts were in vain.
Naldo's 51st-minute strike had put Werder ahead but the same player put through his own net 15 minutes from time to level things up, before Ribery had the final word.
Kaiserslautern claimed their first win in 21 games after seeing off 10-man Hertha Berlin 2-1, but it was not enough to save them from relegation.
Lautern went 2-0 up through goals from Oliver Kirch in the 27th minute and Andrew Wooten 11 minutes later.
Hertha pulled a goal back on the hour mark through Pieter Niemeyer, who was then sent-off 13 minutes from time after collecting a second booking.
Third-bottom Cologne's draw with Stuttgart ultimately proved decisive, though, with Kaiserslautern seven points from safety and facing 2.Bundesliga football next season.
Cologne's point came in a 1-1 draw against Stuttgart, who extended their undefeated run to 10 matches.
Slawomir Peszko gave Cologne the lead after 50 minutes but Cacau equalised for the visitors in the 71st minute.
Bayer Leverkusen kept up the pressure on fifth-placed Stuttgart with a 1-0 win at Hoffenheim.
Andre Schurrle scored the only goal of the game in the 79th minute to earn Sami Hyypia's side all three points and practically secure their place in the Europa League next season.
Sejad Salihovic missed Hoffenheim's best chance from the penalty spot in the 86th minute as Markus Babbel's men lost ground on the top seven.
Nuremberg secured their Bundesliga status with two matches to play thanks to a 1-1 home draw against Hamburg.
Heung-Min Son gave HSV the lead in the 59th minute, only for Daniel Didavi to equalise five minutes later.
On Friday, Mainz secured their top-flight status for a fourth season after recording a 0-0 draw with Wolfsburg.
Saturday's Bundesliga Results
Borussia Dortmund 2-0 Borussia Monchengladbach
Friday's Bundesliga Results