With second-placed VfL Wolfsburg losing 3-2 at Schalke 04, Bayern go seven points clear, having yet to lose in any of the three competitions they are in this season.
Mario Goetze drilled in with Bayern’s first shot on goal in the 23rd minute to go joint top of the scorers’ list with seven and Robert Lewandowski headed in his sixth of the campaign from a cross by Arjen Robben.
The Dutchman then added a third for Bayern, who welcomed back Bastian Schweinsteiger as a second-half substitute for his first appearance since the World Cup final having recovered from a knee injury.
Substitute Sebastian Rode completed the rout to lift Bayern to 30 points. Hoffenheim finished with 10 men following the late dismissal of Adam Szalai.
“We had problems at the start but then we then hit our stride,” said coach Pep Guardiola, whose team travel to Manchester City for the Champions League next week.
“But 4-0 is too much,” said the Spaniard after his team set a club record having conceded just three goals in their opening 12 league matches.
Hoffenheim coach Markus Gisdol heaped praise on his opponents and predicted they would win the title.
“They are the best team and that is why they will be champions again,” he said.
Fellow Champions League club Bayer Leverkusen beat Hanover 96 3-1 with forward Stefan Kiessling ending a drought by scoring his first league goal since August.
Leverkusen are fourth on 20, level with third-placed Borussia Moenchengladbach, who lost 3-1 to Eintracht Frankfurt.
Schalke exploded into action against in-form Wolfsburg, scoring three times in the opening 25 minutes as they prepare to meet Chelsea in the Champions League on Tuesday.
Wolfsburg roared back with goals from Ivica Olic and Nicklas Bendtner and Naldo hit the bar in stoppage time but Schalke hung on to move up to sixth on 17.
Last season’s runners-up Borussia Dortmund, who visit Arsenal in the Champions League on Wednesday, squandered a two-goal lead to draw 2-2 at promoted Paderborn.
There was further bad news for last season’s runners-up as Marco Reus, who had only just returned to the side, was the victim of a robust challenge and was injured again.
Dortmund are 14th on 11 points, two above last-placed VfB Stuttgart.
(Reporting by Karolos Grohmann; editing by Toby Davis)