New signing Pierre-Emerick Aubameyang and Robert Lewandowski netted twice each, Marco Reus capped a virtuoso performance with a goal and Henrikh Mkhitaryan completed the scoring as the Bundesliga leaders made it five wins out of five.
Champions Bayern Munich, also unbeaten and two points behind in second place, rode their luck to beat Hanover 96 2-0 while the club's former player Luiz Gustavo was sent off again for his new team VfL Wolfsburg as they lost 3-1 at Bayer Leverkusen.
Kevin-Prince Boateng's first goal for Schalke 04 earned a 1-0 win at Mainz 05 and Tobias Werner grabbed a stoppage-time goal to give Augsburg a 2-1 home triumph over second from bottom Freiburg who are still without a Bundesliga victory this season.
Vaclav Kadlec's double helped Eintracht Frankfurt win 3-0 at Werder Bremen who had Franco Di Santo sent off after 26 minutes for a dangerous high challenge which left Bastian Oczipka's face splattered with blood.
Dortmund got off to a flying start when Aubameyang and Mkhitaryan put them 2-0 ahead after 22 minutes, only to see Hamburg level through Zhi-Gin Lam's curling shot and a Heiko Westermann header.
New signing Mkhitaryan then combined with Aubameyang before the Gabon forward scored with an angled shot in the 65th minute and Lewandowski added a fourth goal after being set up by a brilliant Reus dummy in the 73rd.
Reus made it 5-2, nonchalantly rolling the ball in after the Hamburg defence twice failed to clear, before Lewandowski headed the sixth with nine minutes to go.
The old Arjen Robben-Franck Ribery partnership was involved in both Bayern goals, with Mario Mandzukic stroking home the first and Ribery sidefooting the second.
Coach Pep Guardiola again fielded captain Philipp Lahm in a new defensive midfield role rather than his usual right back position.
Bayern, who smashed 11 goals past Hanover in their two league meetings last season, were unimpressive in the first half and could easily have been one goal and one man down at halftime.
Didier Ya Konan's shot hit the inside of Manuel Neuer's left post and bounced out while defender Jerome Boateng escaped a red card for a dangerous over-the-ball challenge.
Bayern took the lead in the 51st minute with a slick move which bore the hallmark of former Barcelona coach Guardiola.
Ribery slipped the ball to Robben and the Dutchman carved open the defence with a diagonal pass to Toni Kroos in the area. He then played a first time ball for Croatia forward Mandzukic to sweep home from near the penalty spot.
The second goal started with Ribery feeding Robben whose shot was saved by Ron-Robert Zieler, only for the Frenchman to follow up and sidefoot home the rebound in the 64th minute.
Former Bayern midfielder Luiz Gustavo had a less happy afternoon at Leverkusen as he was ordered off for a second yellow card in the 85th minute, his second dismissal in three games for Wolfsburg.
Stefan Kiessling, the Bundesliga's top scorer last season, scored twice in the second half to give Leverkusen a 3-1 win and take his goal tally for this campaign to four.
Adam Szalai, last season's leading scorer for Mainz, returned to his old hunting ground with Schalke but it was Boateng who stood out, grabbing the only goal in the 34th minute after the hosts gave away possession.
Werder slumped to their third defeat in a row in a match that was effectively settled after 34 minutes when Kadlec gave Eintracht a 2-0 lead.
A miserable day for the home team was completed when Austria defender Sebastian Proedl turned the ball into his own net in the 77th minute.