Li's lawyers said the family will appeal.
The case focused attention on what the Chinese public often deems to be the wayward behavior of children of the privileged and on the sometimes-lenient treatment given to establishment figures by the courts, considered to be under the control of Communist Party leaders.
Li is the baby-faced son of Li Shuangjiang and Meng Ge, both known for singing rousing odes for the People's Liberation Army and starring in television galas.
Liu Shanying, politics researcher from the Chinese Academy of Social Sciences, said the public scrutiny of the case likely played a role in ensuring Li was not acquitted or given a light sentence.
"There has been too much public sentiment involved in this case, namely the hatred of the rich and powerful. That hatred has shaped and dominated the public sentiment," Liu said. "And the ruling has been directly or indirectly influenced by that."
By mid-afternoon, Li's case was the hottest topic in China's Twitter-like Sina Weibo, with his name the most-searched term.
In a news conference, the court took the highly unusual move of commenting on the public attention to trial, saying court officials understood the "grave responsibility" that came with the case and rigorously adhered to China's penal law in handling the case.
"We believed the focus of the public attention was whether the case would be tried strictly by law, and whether the verdict would be just," Fan Jun, a court official overseeing cases involving minors, said at the news conference, according to official transcripts posted online.
The case also had generated discussion of how Chinese courts would deal with violence in cases where the victim's reputation questioned. On Thursday, the court said allegations that the victim might be a prostitute were irrelevant to the rape case.
"The key is whether the female has consented to sex," Fan said.
Li Tianyi said he was drunk and passed out during the incident, that he never beat or had sex with the woman and that he could remember little of the night in question, according to state media.
But the Haidian court said Li was a main culprit, noting Li grabbed the victim's arm and dragged her into the hotel and that Li was seen hitting her head and face in an elevator as recorded on surveillance.
It said Li demanded the woman to disrobe and when she refused, slapped her, kicked her and stripped her with another defendant. It said Li was the first to force sex on the victim.
Li had run into legal trouble before the rape conviction. After beating a couple following a collision in 2011, Li was sent to a labor camp in the widely publicized case.
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News assistant Zhao Liang in Beijing contributed to this report.