Unesco is the first UN agency the Palestinians have sought to join as a full member since President Mahmoud Abbas applied for full membership of the United Nations on Sept. 23.
The United States, Canada and Germany voted against Palestinian membership. Brazil, Russia, China, India, South Africa and France voted in favour. Britain abstained.
Huge cheers went up in Unesco after delegates voted to approve the membership Monday. One shouted "Long Live Palestine!" in French.
Israel said that the vote will harm prospects for the resumption of Middle East peace talks.
"This is a unilateral Palestinian manoeuver which will bring no change on the ground but further removes the possibility for a peace agreement," Israel's Foreign Ministry said in a statement. "This decision will not turn the Palestinian Authority into an actual state yet places unnecessary burdens on the route to renewing negotiations."
On Sunday, Riyad al-Malki, the foreign minister had said of the bid: "This success, if it is realised, and with this large number of votes, will give a great boost to the efforts that we are making to get the required vote in the United Nations."
Admission will be seen by the Palestinians as a moral victory in their bid for full UN membership.
Washington, which has the power to veto such applications, opposes the Palestinian bid for a full UN seat on the grounds it is unhelpful to efforts to revive peace talks with Israel, the last round of which broke down a year ago.
Israel's closest international ally, the United States has said it will use its veto power in the Security Council to quash the bid for full UN membership, were it brought to a vote.
But Unesco is one of the UN agencies the Palestinians can join as a full member regardless of their broader status at the United Nations, where they are currently classified as "an observer entity".
Palestinian success could bring a financial cost for Unesco. Under US law, the admission as a full Unesco member would trigger a cut-off in US funding which accounts for 22 per cent of the agency's funding.