The 17-year-old had also been linked with German giants Bayern Munich and Borussia Dortmund, but he will now join Leverkusen in January, despite initially agreeing to make the switch at the end of the season.
Brandt has signed a five-and-a-half-year contract with the Bundesliga outfit and Voller thinks that his capture will pay dividends as he anticipates a bright future for the Germany Under-19 international.
"Julian Brandt is one of the most gifted youngsters in the German game," he told Deutsche Presseagentur.
"His signature is a great investment for the future of Bayer Leverkusen.
"Julian will be with the first-team squad of our club for the training camp in Portugal in January 2014 to enable him to experience life with the professionals as early as possible."