The lethal hazing of the 26-year-old occurred after the band's performance at a football game in Orlando last November, the Orlando Sentinel reported.
Prosecutors said 11 of the 13 students face felony hazing charges.
Orange-Osceola State Attorney Lawson Lamar, who announced the charges at a news conference Wednesday, called the case "an American tragedy."
"No one would have expected that his college experience would have included being pummeled to death," Lamar said.
Lamar said no names of the suspects would be released until all are in custody.
Christopher Chestnut, the attorney for Champion's family, said the Champions were disappointed the charges weren't more serious. He said the family learned about the charges an hour before the announcement.
"Their son is dead. He was beaten to death on a bus -- that constitutes murder," Chestnut said.
Lamar said he pursued only hazing charges because they would be easier to prove, requiring only evidence of participation in hazing and that there was a death.
"It's a very different burden of proof than we have in a homicide case," Lamar said.
The Sentinel said state prosecutors have been considering charges since March, when the Orange County Sheriff's Office and Florida Department of Law Enforcement turned over their findings to prosecutors.
In the hazing incident aboard a charter bus, Champion was punched, kicked and suffocated by band members, the Champion family's attorney said. The family also has filed a wrongful-death lawsuit against the charter bus company and bus driver.
Lamar said up to 20 misdemeanor charges are also being filed involving "different victims who were not seriously injured."