Frankfurt dominated the first half, Takashi Inui hitting the post after 10 minutes, although they had a let off when Simeon Jackson intercepted a back pass but saw his effort saved by Frankfurt goalkeeper Kevin Trapp.
The Eagles went ahead early in the 52nd minute when a shot by Alexander Meier, making his 250th league appearance for the club, took a wicked deflection off Ermin Bicakcic's shoulder and flew in at the near post. The goal was awarded to Meier, making it the 50th he has scored in the Bundesliga.
Ten minutes later Braunschweig lost possession as they tried to play the ball out of defence.
Omar Elabdellaoui's pass across the face of the penalty area was intercepted by Stefan Aigner, who ran on to fire a low, right-foot shot past the helpless Daniel Davari.
(Writing by Brian Homewood in Berne; Editing by Pritha Sarkar)
