The incident occurred at the Town Center Mall in Kennesaw on Thursday, police said.
The suspect, Andres Wilhelm Schafer, molested a 7-year-old at a Belk store, police said. Police said Schafer, 31, touched the child inappropriately twice, once on an escalator and once in the store's shoe department.
Investigators charged Schafer after the girl told a family member what had happened. The victim's 10-year-old sister also witnessed one of the incidents, police said. Mall security then grabbed Schafer before he could leave.
Police said Schafer did not know the victim.
Schafer was arrested and charged with three counts of child molestation. He was being detained by U.S. Immigrations and Customs Enforcement.