The singer, who was set to make his comeback at the event, backed out of the performance, blaming "scheduling conflicts" for the decision, reports Music-News.
Williams recently appeared on the television show X Factor. He enjoyed his stint on X Factor so much that he quickly accepted offers for other shows, including the MTV Europe Music Awards, and the BRIT Awards in February.
However, he mysteriously cancelled the MTV gig just a week before, and gave no further explanation.
The MTV gala will be held on November 5 in Berlin, and will highlight the 20th anniversary of the falling of the Berlin Wall. The show will be hosted by singer Katy Perry. Among the artists who will be performing are Foo Fighters, Green Day, Jay-Z, Leona Lewis, Shakira and Tokio Hotel. U2 will also perform in front of the Brandenburg Gate.