The motion, requesting British "military action, specifically airstrikes, exclusively against IS in Syria," was approved by 397 votes to 223, Xinhua reported.
The approval will pave the way for British warplanes to extend their bombing missions from Iraq to Syria.
Britain has been bombing IS in Iraq since the House of Commons voted to authorise airstrikes in the Middle East country in September 2014.
Speaking after the vote, British Foreign Secretary Philip Hammond said: "Britain is safer because of the actions taken by MPs today."
He added that he was "very pleased that a significant number of Labour MPs voted with us to degrade this terrorist organisation".
British members of the Parliament (MPs) clashed bitterly in a whole day of heated debate in the House of Commons over whether to extend British airstrikes against the IS targets to Syria.
Opening the debate on Wednesday, British Prime Minister David Cameron said Britain "should not wait any longer" before reducing the treat from IS to its security.
"We should answer the call from our allies. The action we propose to take is legal. It is necessary, and it is the right thing to do to keep our country safe," he said in his opening speech.
Describing IS militants as "women-raping, Muslim-murdering, mediaeval monsters," Cameron said he wants to "pursue a comprehensive strategy that also includes political, diplomatic and humanitarian action."
Jeremy Corbyn, leader of the opposition Labour Party, opposed extending Britain bombing into Syria, warning that "the prime minister's proposal for military action simply does not stack up."
"For all members, taking a decision that will put British service men and women in harm's way and almost inevitably lead to the deaths of innocents is a heavy responsibility," he said.