Yitzhak Bergil, a member of the Neturei Karta sect, was charged with intending to commit treason and contacting a foreign agent in August.
He has confessed to the charges, and reached a 4 /12 year prison sentence deal with the Jerusalem State Attorney's Office, the Jerusalem Post reported.
The Jerusalem District Court approved the deal Tuesday.
Bergil made contact with the Iranian government and offered to spy in an attempt to replace Israel's leadership with non-Jews.
Neturei Karta rejects Zionism and opposes the existence of Israel.
Members of the sect have burned the Israeli flag and sent representatives to attend conferences in Iran.