كتب : Omar Zaazou
Kahraba broke the deadlock at the stroke of half time before Croatian defender Tomislav Puljic made it two nine minutes from the end.
Making his full debut, the 19-year-old Kahraba hit his maiden Luzern goal on his fourth appearance, having made cameo appearances in previous league games.
He made a superb darting run in Zurich's half before being played through to slide home his side's first of the night.
The win lifts Luzern to third place on 18 points, one point adrift of leaders Basel who take on Lausanne the next day.