The German international sealed a move to Stamford Bridge last month, and despite speculation linking the club with Wayne Rooney, Voller believes that the 22-year-old can become one of the world's best under Jose Mourinho.
"Andre can become an absolute world-class player," Voller told German tabloid Express.
"He needs to gain more ruggedness and has to become more forceful. That is important - most of all in England. If he gains on those areas he will become a big player."
Voller also spoke of Germany's hopes at the World Cup next summer, and believes that Schurrle will have a major role to play in the national team's future success.