US House of Representatives Speaker John Boehner's invitation on Wednesday to Netanyahu - whose relationship with President Barack Obama has been acrimonious - had drawn criticism from the White House, which said it had not been consulted.
Shortly before Netanyahu's formal acceptance of the invitation, Israel's Mossad intelligence chief publicly closed ranks with the right-wing prime minister - denying in a rare press statement reports that he opposed further sanctions on Iran while world powers negotiate with the Islamic Republic on limits to its disputed nuclear programme.
On his Twitter page, Boehner said the Congressional address was scheduled for March 3 - exactly two weeks before Israel's general election in which Netanyahu is vying for a fourth term.
Netanyahu's office said the Israeli leader would also attend the March 1-3 annual policy conference in Washington of the prominent pro-Israel AIPAC lobby.
Netanyahu has long faced opposition from Israeli security chiefs to unilateral military action against Iran; they fear it could lead to protracted conflict and severe damage to Israel.
AT LOGGERHEADS OVER IRAN
Netanyahu, who has frequently clashed with Obama over the Iranian issue and Jewish settlement on occupied territory that Palestinians seek for a state, has accused the president of making too many concessions to Tehran for too little in return.
The Democratic president has said he would veto Iran sanctions legislation in the works in Congress because it could undermine the chances of a nuclear settlement with Tehran.
Resistance from Mossad chief Tamir Pardo to new sanctions could have weakened what is expected to be a Netanyahu call to U.S. lawmakers for tougher economic penalties against Iran.
"The head of the Mossad stressed (in a meeting last week with visiting U.S. senators) that the exceptional effectiveness of the sanctions imposed on Iran in recent years are what brought Iran to the negotiating table," the statement said.
In the absence of strong pressure, it added, "the Iranians will make no meaningful compromises".
Israeli political commentators portrayed Boehner's invitation as either a Republican attempt to give Netanyahu a boost in the election campaign or an Israeli bid to meddle in U.S. politics - or both.
Some analysts said however that a third Netanyahu address to Congress would have little impact on Israelis long accustomed to his oratory skills in English on the international stage.
His main challenger in what polls show is a neck-and-neck race, Labour Party chief Isaac Herzog, cautioned against further straining Netanyahu's relations with Obama.
"We need the president on our side, day and night, on so many sensitive and important issues," Herzog said.
In his statement, Netanyahu appeared to try to smooth over any ruffled feathers at the White House.
He said he was "honoured to accept the invitation" and that would use the speech "to thank President Barack Obama, Congress and the American people for their support of Israel".
