State prosecutors in Gera, Thuringia, said that Brandt, 39, would answer 157 charges for acts that took place between 2011 and 2014.
“This means that he himself had sexual contact with children and young people,” a spokesman for the prosecutor's office said.
Brandt is accused of having supplied minors to adults for sex in exchange for money in 45 cases.
As leader of the “Thuringia Homeland Defence” group, Brandt had contact with the National Socialist Underground members Uwe Mundlos, Uwe Böhnhardt and Beate Zschäpe before they began their serial murders.
News of the charges against Brandt came just one day after his handler from the Office for Constitutional Protection (Verfassungsschutz) had given evidence at Zschäpe's trial.
Prosecutors said that there was no connection to his political opinions in the present charges.
They added that Brandt, who has been in custody since June during the investigation, had co-operated with the investigation and admitted to some of the allegations.