Ahmed Bassam Zaki, in his early 20s, was referred to trial by public prosecutors in September on charges of the indecent assault and blackmail of at least three women, all under 18 at the time, between 2016 and 2020. He was detained in July.
Zaki, who was the target of a flurry of accusations on an Instagram account, showed no reaction as the sentence was read out at the criminal court in Cairo, the sources said.
He is not known to have addressed the accusations publicly and Reuters was not able to locate a lawyer representing him.
Zaki can appeal against the ruling before the court of cassation, Egypt's top civilian court, the sources said.
The case attracted widespread attention from media, religious figures and women's groups in a country where rights defenders say sexual harassment or abuse often goes unpunished.
Zaki was sentenced to three years in jail by another court in December for harassing two girls online. He has appealed against the ruling.