Their right-wing "Freedom Alliance" took an absolute majority of 366 seats in the 630-member Chamber of Deputies and a qualified majority of 155 in the Senate, according to official returns.
Italy's neo-fascists were jubilant after scoring their biggest success since the rule of dictator Benito Mussolini.
The result was a crushing defeat for former communist Achille Occhetto, who seemed assured of victory until Berlusconi burst onto the scene just two months ago promising a "new economic miracle."
Occhetto's broad left Progressives pact was a distant second on 213 seats in the lower house. Of the remainder, 46 went to a small centrist alliance including the rump of the Christian Democrats.
As the extent of the triumph emerged, Berlusconi, owner of Europe's largest private media empire and soccer champions AC Milan, pledged to work fast to give Italy its 53rd government since World War II.
Strains in the fractious alliance led by his Forza Italia party, particularly with the federalist Northern League, could cloud the chances of rapid success but Berlusconi said he was confident.
"I do not believe that there will be any betrayal of the electorate which has said exactly what it wants -- a united alliance which gives the country a majority and a strong, authoritative government," he told a radio interviewer.
Gianfranco Fini, leader of the neo-fascist National Alliance, also called for a swift government accord.
"Tonight all of Italy knows we have finally won," Fini told a jubilant midnight victory rally in Rome to straight arm salutes from young supporters.
Financial markets had surged on Monday on rumors of a clean sweep for the right and on Tuesday operators remained happy with the result.
"The markets have got much of what they wanted. We have a winner. But now we need to see if we will get a government," said Banca di Roma economist Fabrizio Mennella.
Umberto Bossi, leader of the Northern League,which won 8.4 percent, insisted Berlusconi's vast business interests disqualified him from becoming prime minister. The League's support may be necessary to Berlusconi.
Berlusconi's Forza Italia polled 21 percent, Occhetto's ex-communist Democratic Party of the Left 20.4, and the National Alliance 13.5, according to returns for a proportional section of the lower house vote.
No percentages were available for individual alliance members in the more important constituency voting.
A Message from The Moscow Times:
Dear readers,
We are facing unprecedented challenges. Russia's Prosecutor General's Office has designated The Moscow Times as an "undesirable" organization, criminalizing our work and putting our staff at risk of prosecution. This follows our earlier unjust labeling as a "foreign agent."
These actions are direct attempts to silence independent journalism in Russia. The authorities claim our work "discredits the decisions of the Russian leadership." We see things differently: we strive to provide accurate, unbiased reporting on Russia.
We, the journalists of The Moscow Times, refuse to be silenced. But to continue our work, we need your help.
Your support, no matter how small, makes a world of difference. If you can, please support us monthly starting from just $2. It's quick to set up, and every contribution makes a significant impact.
By supporting The Moscow Times, you're defending open, independent journalism in the face of repression. Thank you for standing with us.
Remind me later.