The survey by the Swg institute gave Berlusconi's People of Freedom (PdL) party 27.9 percent, the centre-left Democratic Party (PD) 24.0 percent and the anti-establishment Five Star Movement 20.1 percent.
The PdL came a very close second to the PD in February parliamentary elections that led to a two-month political stalemate.
Compared to the February election results, the poll shows a slight drop for the PD, a bigger fall for the Five Star Movement and a major rise for Berlusconi.
The telephone survey was carried out on Tuesday and Wednesday before the cabinet agreed to a demand from the PdL to scrap an unpopular property tax, which may give Berlusconi a further boost in the polls.
The poll for Rai 3 television had 1,500 respondents.
The PD and PdL, two traditionally rival parties, are now in an uneasy coalition led by Prime Minister Enrico Letta which appears constantly under threat.
Berlusconi this month lost his final appeal against a tax fraud conviction and faces possible expulsion from parliament for the first time in his political career.
His supporters have threatened to resign from their seats in parliament if the PD goes ahead with the Senate vote required to eject Berlusconi from the chamber.
A court in October is also due to decide whether he will have to serve out his one-year prison sentence under a form of house arrest or community service.
Berlusconi is also appealing convictions for having sex with an underage teenage prostitute, for abusing the powers of his office and for leaking a police wiretap in an attempt to damage a political rival.
Despised by Italian leftists, he remains enduringly popular despite the scandals among a core electorate which sees him as a victim of judicial persecution and a defendant of free-market capitalist principles.
Observers have repeatedly predicted the political demise of the 76-year-old billionaire tycoon and three-time prime minister, only to see him rise again.