The prosecutors, who filed their request in Milan, are seeking a trial now because they believe there is overwhelming evidence against the 74-year-old leader.
A judge must decide whether to accept the prosecutors' request and indict Berlusconi, or dismiss it. The decision is expected to be made in the next two weeks.
Berlusconi has a long history of legal woes and fierce battles with the Italian judiciary, which he accuses of being politically motivated against him. But this is the first judicial action that targets his private life and not his business dealings as a media mogul, raising new questions over how long he can hold on to power.
The case centers on his relationship with the Moroccan nightclub dancer nicknamed Ruby. Italian newspapers have been filled for weeks with salacious details about Berlusconi's parties at his villas, based on wiretaps of conversations between women who attended them.
"It's shameful, really," Berlusconi told reporters Wednesday in Rome, criticizing the prosecutors' move. "It's shameful and disgusting."
"I wonder who's going to pay for these activities that, in my humble view, only have a subversive aim," Berlusconi added, lamenting that the case had "offended the dignity of the country."
In Milan, dozens of his supporters rallied against the prosecution's decision, some waving Italian flags across the street from the courthouse.
The prosecutors allege that Berlusconi paid for sex with Ruby, who has since turned 18, then used his influence to get her out of police custody when she was detained for the suspected theft of ¿3,000 ($4,103), allegedly fearing her relationship to him would be revealed.
Ruby ultimately was released into the custody of a Berlusconi aide who also is under investigation.
Paying for sex with a prostitute is not a crime in Italy, but it is if the prostitute is younger than 18.
The child prostitution charge carries a possible prison sentence of six months to three years; the abuse of influence charge, which experts say is more dangerous for Berlusconi, carries a possible sentence of four to 12 years.
Both Ruby and Berlusconi have denied a sexual relation.
The premier's supporters say he made the call to avoid a diplomatic incident because Berlusconi believed at the time that the girl was the niece of Egyptian President Hosni Mubarak. His defense maintains the case should be handled not by the Milan prosecutors but by a special tribunal set up to deal with alleged offenses committed by public officials.
"I have intervened as prime minister because I was worried that there could be an international diplomatic incident," Berlusconi said Wednesday.
The prosecutors insist they don't believe the alleged crime was committed in the exercise of Berlusconi's institutional duties.
"This is not an act that can be ascribed to his office," said Prosecutor Edmondo Bruti Liberati. He noted Berlusconi as premier does not have control of police forces, but in calling police he abused his influence.
The prosecutors have transferred a 782-page document to the office of the judge who has to make the decision, Cristina Di Censo, including wiretaps of conversations among participants at Berlusconi's parties.
In some purported conversations, Berlusconi's house is described as a brothel with topless girls dancing around; the premier himself is described as a "caricature" by one guest and as having gained weight and having become ugly by another. Other published wiretaps have a woman identified as Ruby saying that Berlusconi was willing to pay for her silence.
The transcripts were sent weeks ago from the Milan prosecutors to a parliamentary commission in Rome examining documents relating to the investigation - and they were soon leaked to the Italian press.
Although allegations of Berlusconi's sexual escapades have been raging for more than a year, opposition politicians have been unable to capitalize on them as Berlusconi continues to hold a narrow majority in parliament despite the loss of a key ally.
There have been many protests, and one is planned this weekend by women who say they are insulted. Yet demonstrations have been held heavily along the ideological divide. Just this week five women lawmakers from Berlusconi's party appeared on a major TV talk show to defend the premier and say the charges against him are lies.
While this is the first legal case to touch on Berlusconi's private life, it is not the first sex scandal that has engulfed the premier.
In one case, Patrizia D'Addario, a self-described call girl, said she spent the night with Berlusconi when Barack Obama was elected U.S. president. She later gave purported tapes of her encounter with Berlusconi to an Italian magazine.
In 2009, his second wife, Veronica Lario, announced she was divorcing him, citing Berlusconi's purported fondness for younger women. Berlusconi has made no apologies for his lifestyle, but has denied ever paying to have sex.
Berlusconi's legal worries also include several cases pertaining to his business dealings that are set to resume in the coming weeks, after Italy's Constitutional Court weakened a law that had temporarily shielded the premier from prosecution. Since the decision last month, court dates have been set in trials where Berlusconi is charged with tax fraud and bribery.
Another tax fraud case, but pertaining to more recent events than the ongoing Mediaset trial, will continue its preliminary hearing next month.
Berlusconi has always denied wrongdoing in the many cases involving is media empire, and has always either been acquitted or seen the statute of limitations expire - something that is considered likely in the two trials now under way.
Berlusconi was elected at the helm of a conservative coalition in 2008 for a five-year term. In December, he narrowly won back-to-back confidence votes in Parliament.
Rizzo reported from Rome.