Dortmund forward Pierre-Emerick Aubameyang snatched a 55th-minute equaliser to become the first Bundesliga player ever to score in each of the opening six matches of a season, after the hosts had gone ahead with Sebastian Rudy before the break.
But it was not enough for Dortmund, who have 16 points. Before Wednesday, they had won all 11 matches in all competitions this season to register the club's best start.
"I would not call it a reality check but we did miss a few percentages tonight," Dortmund coach Thomas Tuchel told reporters. "But we should be careful not to feel as if we've lost because in three days we will start a new winning run."
Champions Bayern are on 18 points after crushing VfL Wolfsburg 5-1 on Tuesday with Robert Lewandowski scoring all five goals in nine minutes, for the fastest hat-trick and five-goal run in the league's history.
Rudy put Hoffenheim, still without a win this season, in the lead against the run of play with a low drive in the 42nd minute.
Eduardo Vargas thought he had scored again for the hosts when he pounced on a Matthias Ginter mistake to chip the ball over keeper Roman Buerki but hit the post.
Instead it was Dortmund who struck, with Aubameyang on target from close range 10 minutes after the restart.
Despite pressing for a second goal and creating several good chances, Dortmund failed to score again and had to settle for their first draw of the season.
Schalke 04 leapfrogged into third place on 13 points with a 2-0 victory over Eintracht Frankfurt, with both goals coming in the final 14 minutes.
Bayer Leverkusen's Chicharito grabbed his first Bundesliga goal in their 1-0 win over Mainz 05 to end a three-game losing run and climb back up to 11th on nine points.
Two days after coach Lucien Favre quit, Borussia Moenchengladbach scored four times in 16 minutes to beat Augsburg 4-2 for their first win of the season after five straight losses and their worst start to a season.
The win under interim coach Andre Schubert lifted Gladbach off the bottom and into 16th place, a spot behind VfB Stuttgart, who came from a goal down to beat Hanover 96 3-1 to score their first points of the season.
(Reporting by Karolos Grohmann, editing by Pritha Sarkar)
