Joshua Kimmich and Lennart Karl scored for the defending champions, while Philipp Tietz netted a late consolation goal for Mainz as Bayern claimed another important three points.
Bayern started the encounter confidently and took control of possession from the opening minutes. Their pressure paid off in the 14th minute when Kimmich opened the scoring with a superb long-range effort.
Harry Kane won possession following a misplaced pass from Jae-Sung Lee before setting up Kimmich, who drove towards the edge of the penalty area and fired a powerful shot into the top corner beyond goalkeeper Robin Zentner.
The visitors continued to dominate, with Nathaniel Brown and Dayot Upamecano both testing Zentner as Bayern searched for a second goal.
Mainz briefly threatened an equaliser when Jae-Sung Lee headed the ball into the net from Nadiem Amiri's free-kick. However, the goal was ruled out for offside following a VAR review.
Bayern also suffered a setback before half-time when goalkeeper Manuel Neuer was forced off with an injury in the 40th minute. Jonas Urbig replaced the experienced goalkeeper.
The visitors went into the break with a deserved 1-0 advantage.
Bayern continued their attacking approach after the restart and doubled their lead in the 54th minute.
Kane was again involved in the build-up, with the England captain recovering the ball after his initial effort was blocked before laying it into the path of Lennart Karl.
The young forward made no mistake, calmly finishing past Zentner to put Bayern 2-0 ahead.
Karl's goal gave Bayern greater control of the contest, although Mainz continued to fight for a way back into the match.
Bayern came close to extending their advantage through Upamecano, whose powerful header struck the crossbar, while Zentner also produced important saves to prevent further damage.
Mainz eventually found the net in the third minute of stoppage time. Benedict Hollerbach delivered a cross from the left, and Philipp Tietz rose above the Bayern defence to head home and reduce the deficit to 2-1.
However, the late goal proved insufficient as Bayern comfortably managed the remaining minutes to secure victory.
The result extended Bayern's unbeaten away run in the Bundesliga to 31 matches and kept them at the summit with 21 points from nine games, level with Borussia Dortmund.
Mainz remained on 10 points after suffering another league defeat.
Match details
• Competition: German Bundesliga
• Date: Saturday, 7 November 2026
• Venue: MEWA Arena, Mainz
• Half-time: Mainz 0-1 Bayern Munich
• Full-time: Mainz 1-2 Bayern Munich
Goalscorers
• Bayern Munich: Joshua Kimmich 14', Lennart Karl 54'
• Mainz: Philipp Tietz 90+3'