The German champions produced a disciplined performance at the Parc des Princes, with an own goal from PSG goalkeeper Katarzyna Kiedrzynek and a strike from Klara Bühl giving them a two-goal advantage before half-time.
Bayern started brightly and created several opportunities before taking the lead in the 29th minute. Pernille Harder delivered a dangerous ball towards the goal, which goalkeeper Kiedrzynek inadvertently diverted into her own net.
The visitors doubled their advantage in the 40th minute through Bühl, who finished confidently after receiving an excellent through pass from Harder.
Dudek gives PSG hope
PSG returned for the second half with greater attacking urgency as they attempted to recover from their two-goal deficit.
Their persistence paid off in the 65th minute when the referee awarded a penalty following a handball by Bayern's Linda Dallmann.
Captain Paulina Dudek stepped forward and calmly converted from the spot to reduce the deficit to 2-1.
The goal gave the hosts renewed belief, and they pushed forward in search of an equaliser. Merveille Kanjinga and Tara Elimbi Gilbert both had opportunities late in the contest, but Bayern's defence stood firm.
The German side successfully protected their advantage until the final whistle to claim a valuable away victory.
Bayern strengthen Champions League ambitions
The result moved Bayern Munich into second position in the league-phase standings, strengthening their hopes of securing automatic qualification for the quarter-finals.
For PSG, the defeat ended their unbeaten start to the competition and left them with work to do in their remaining fixtures.
Bayern will now turn their attention to a Bundesliga meeting with Wolfsburg, while PSG prepare for their domestic fixture against Marseille before travelling to England to face Chelsea in their next Champions League assignment.
Full-time: Paris Saint-Germain Women 1-2 Bayern Munich Women
Competition: UEFA Women's Champions League, 2026/27 league phase, Matchday 4.
Venue: Parc des Princes, Paris, France.
Goals:
Bayern Munich: Katarzyna Kiedrzynek 29' (OG), Klara Bühl 40'.
PSG: Paulina Dudek 65' (pen).