Trent Mays, 17, was sentenced to a minimum of two years in juvenile detention, with the maximum sentence being until he reaches the age of 21. Ma'lik Richmond, 16, was sentenced to a minimum of one year.
Richmond wept openly after the verdict was announced. After the sentencing, both teens apologized to the victim, who was from a nearby West Virginia town, and the community.
Mays received the extra year for a charge of illegal use of a minor in nudity-oriented material. He apologized for taking the photo of the girl, posted online, that brought the case into the public eye.
About 30 protesters against violence directed at women applauded and cheered outside the courthouse when the verdict was announced.
Both teens maintain their innocence. The accuser took the stand Saturday and testified that she could not recall what happened the night of the attack before waking up naked in a strange house.
The alleged victim said she drank a mixed drink, spiked punch and a shot before leaving the party with Mays, WKYC in Cleveland reports. The girl said she suspects she was drugged because of how intoxicated she became that night.
"I remember walking down the steps and in the street. That was it," she said.
The prosecution says Mays and Richmond sexually assaulted the intoxicated girl in the back of a car, and then in the basement of a house where she later awoke, naked. She testified she could not find her cellphone, earrings, shoes or underwear.
"It was really scary," she testified. "I was embarrassed and scared. I didn't know what to think. I couldn't remember. I woke up with no clothes on. I didn't know what happened at all."
The girl said she did not learn of the alleged assault until she saw a photo from that night and a friend gave her the link to a video posted on YouTube in which a student joked about the assault.
When the accuser was shown a nude photo of herself that students had shared through text messages, she broke down and cried on the stand.
She testified she did not remember being photographed as Mays and Richmond carried her, in an image that was widely circulated on social media sites.
Gionna Anile, a former friend of the alleged victim, testified she tried to stop the girl from leaving the party with Mays and Richmond.
Anile testified she picked up the alleged victim the next morning where she found her lying on a couch in the basement of a Steubenville student's home, the Cleveland Plain Dealer reports.
The alleged victim did not seem upset, Anile said, and was primarily concerned with finding her cellphone.
Anile asked the girl what happened the night before.
"We didn't have sex, I swear," the alleged victim said at first, according to Anile. But soon after that the girl said she didn't remember what happened.
West Virginia high school student Kelsey Weaver said the accuser told her what happened two days after the alleged attack then, sometime afterward, told Weaver she couldn't remember what happened.
"So two different versions?" asked Mays's attorney Adam Nemann.
"Yes," Weaver replied.
Weaver also said the accuser had been flirting with Richmond at the party.