The Supreme Court declared the ruling on Monday, which calls for all preparations for the September 25 vote to be halted, following a review of multiple "requests to stop the referendum".
"The supreme court has issued the order to suspend organising the referendum set for September 25 ... until it examines the complaints it has received over this plebiscite being unconstitutional," it said in a statement.
Iraq's prime minister Haider al-Abadi, had previously demanded the suspension of the referendum.