Around 500 relatives attended the ecumenical service, with hundreds more watching on large screens outside the cathedral and in a neighbouring church. During the service 150 candles are to be lit to mark each of the lives lost.
According to AP, Cardinal Rainer Maria Woelki, the archbishop of Cologne, told victims' relatives that words alone were too weak to give them any solace, but that they should take comfort in the numbers of people at the memorial service, and those following it online or on television.
"You are not alone in these hours of loneliness," he said.
A choir also sang hymns, and religious leaders said multidenominational prayers.
The crash was intentionally caused by the co-pilot, Andreas Lubitz. Having previously been treated for suicidal tendencies and been declared "unfit to work" by a doctor, Lubitz kept this information from his employer and reported for duty.
During the flight, he locked the captain out of the cockpit before initiating a descent that caused the plane to crash into a mountain.
