Having trained in Leipzig with Karl Piutti and Carl Reinecke and Munich with Ludwig Thuille and Josef Rheinberger, he secured his first significant academic post at the young age of twenty-three, when he was appointed deputy director of the Stern Conservatory, Berlin.
In September 1939, Willner and his wife, Cecile Taufstein (°Paris, 31 January 1882[5]), moved to Kington, Herefordshire, to stay at the gardener's cottage at Gravel Hill, residence of English composer E. J. Moeran's family.
Willner remained here until 1945, when Cecile became fatally ill and, after a short period in Edgbaston Hospital in Birmingham, she was moved to a nursing home in London.
Despite his relatively prominent place in the German musical establishment during the first part of the century, most of his works are now completely unknown and many believed lost.
[7] Otherwise he is best remembered for arrangements, such as his string orchestra transcription of Béla Bartók's Romanian Folk Dances for piano, and for his orchestral reduction of Richard Strauss's Oboe Concerto.