Now _ dogged by a sex scandal and ordered back to trial this week to face corruption and fraud charges _ he's staring into the abyss of a spectacular downfall.
But this master of self-transformation has bounced back from scandal countless times in the past, and the Constitutional Court's decision Wednesday to lift his political immunity as premier may be just another chink in the leader's Teflon armor.
With the opposition in disarray, the Italian people still behind him and almost inexhaustible avenues for appeal, Berlusconi's fate ironically rests with his political allies. The most dangerous are key figures of his own coalition: one the boisterous head of a xenophobic party, the other a cool-headed former neo-Fascist who considers himself the media magnate's successor.
Despite setbacks that would have cost other leaders their jobs long ago, the 73-year-old leader says he has no intention of stepping down and intends to serve the final 3 1/2 years of his term.
He has launched into combat mode, denouncing the high court judges as "leftists" and implying that the president _ a dignified figure who has sought to be a voice of reason _ is a communist stooge.
There's little question the high court's decision to remove Berlusconi's immunity as premier _ clearing the way for his corruption trial to resume _ is a massive political blow that could hobble his premiership if he holds onto power.
Preparing for court appearances and defending himself against political attacks will prove a major distraction from such critical issues as Italy's economic crisis and Afghanistan, where six Italian troops recently were killed in a bombing.
Stefano Folli, a commentator for the business daily newspaper Il Sole 24 Ore, calls this the "most critical moment of his political life."
But Berlusconi is never quite so alive as when he's battling his critics _ and the Italian public often appears to applaud the spectacle of the premier sneering and snarling as he fends off his accusers.
Berlusconi's enduring popularity may lie partly in the way he's seen by millions as the living embodiment of their dreams _ a leader who rose from nothing to become Italy's richest and most powerful man, wielding the reins of state even as he parties on yachts with starlets.
As a businessman, he's shown a genius for tapping into powerful national obsessions.
In a soccer-crazy nation, he owns AC Milan, one of Italy's most successful clubs. And his media empire has fed Italy an endless stream of glitz that has helped the masses vicariously live "la dolce vita" _ the sweet life.
Polls have shown that Berlusconi, who has ruled for seven of the past eight years, enjoys broad support despite repeated scandals. His wife has accused him of having inappropriate relationships with far younger women _ one was 18 _ and a self-described call girl said he spent a night with her.
Berlusconi says he is "no saint" but has denied ever paying anyone for sex or having any improper relationships.
The premier said Thursday he will go on TV and appear in courtrooms to prove that corruption and tax fraud charges in two trials against him are false.
"These two trials are laughable, they are a farce which I will illustrate to Italians also by going on TV," Berlusconi said. "I will defend myself in the courtrooms and ridicule my accusers, showing all Italians ... the stuff I am made of."
If anyone proves to be Berlusconi's downfall it could very well be his coalition partners.
One key ally, Umberto Bossi, head of the anti-immigrant Northern League, said he needs the government to carry out its promised federalist reforms, shifting some tax and other powers away from Rome to the regions.
Berlusconi is generally luewarm to federalism _ but would cross the unpredictable Bossi at his peril: he brought down Berlusconi's first government after only a few months in 1994. The premier's legal woes could turn him into a hostage to Bossi's whims, and make him lose credibility with the public.
Gianfranco Fini, the speaker of the lower house, is sounding ever-more statesmanlike as he moves from the far-right to mainline European conservatism. Italian newspapers said he was irritated by Berlusconi's attacks on the president, and he has increasingly appeared to distance himself from his partner in power.
If Berlusconi is dragged into a legal quagmire, Fini may find it ever harder to resist a grab for power. And in stark contrast to Berlusconi's sleazy image, Fini comes across to the public as squeaky clean.
The corruption trial is particularly threatening for Berlusconi, because the premier's co-defendant already has been convicted of accepting a bribe to lie in court to protect Berlusconi.
Even if convicted, Berlusconi could still stay in power _ sentences in Italy are usually not served until all avenues of appeal are exhausted.
His lawyers said the trial would have to start anew, making it possible that the statute of limitations will kick in before it is completed.
In the Milan corruption trial, Berlusconi was accused of ordering the 1997 payment of at least $600,000 to British lawyer David Mills in exchange for the lawyer's false testimony at two hearings in other corruption cases in the 1990s.
Berlusconi faces the tax fraud charge in a trial over Mediaset's purchase of TV rights.
In a separate ruling just a few days ago, Fininvest was ordered to pay euro750 million ($1 billion) to a rival for its 1990s takeover of the Mondadori publishing house. Fininvest said the ruling is unjust and it will seek to suspend the "absurd" judgment pending an appeal.
The civil damage award stems from a case in which three Berlusconi associates were convicted of corrupting a judge so he would overturn a ruling that had gone in favor of industrialist Carlo De Benedetti and against Berlusconi for control of Mondadori.
It is De Benedetti's media group that has been spearheading the coverage of the sex scandal, including putting a tape on its Web site of spicy conversations in bed between a call girl and a man it identified as Berlusconi.
Rome Bureau Chief Victor L. Simpson has covered Silvio Berlusconi since the media magnate entered politics.