The prince, 26, said he was sure she would have been "proud" of his work in Africa for which he picked up a Golden Heart gong on the German fund-raising TV show 'Ein Herz fur Kinder' ('A Heart for Children').
He told Germany's Bild newspaper: "I always think of my mother in everything I do. I hope she would be proud of my work. My brother and I often ask ourselves: what would our mother have done in this situation?
"That helps us again and again. But I learned also enormously from my father who has been engaged with numerous charities for decades."
At the awards the wife of German President Christian Wulff, Bettina presented him with the honour saying: "You have helped 3,000 children so far.", to which the prince replied in a mix of English and German: "From the bottom of my heart, Vielen Dank."
He then added: "Compared to so many people who devote their whole lives to restoring hope to children around the world, I have done very little."
While in the city, Harry laid a wreath at a memorial to those killed at the Berlin Wall trying to escape from communist East Germany and met a Holocaust survivor at a Jewish museum.
