Four RAF Tornado jets, which carry a range of munitions including Paveway IV guided bombs and precision-guided Brimstone missiles, took off from the Akrotiri base in Cyprus, reportedly targeting an oil field in eastern Syria.
A Ministry of Defence spokesman said the sorties had returned from the "first offensive operation over Syria and have conducted strikes".
Prime Minister David Cameron has said MPs took the "right decision to keep the UK safe" after they overwhelmingly backed air strikes.
MPs voted by 397 to 223 last night in favour of extending British action to quash IS, also known as Isis, Isil and Daesh, from Iraq into its Syrian strongholds - a majority of 174.
Shadow foreign secretary Hilary Benn was lauded by MPs from across the House for making a powerful speech warning his party that "we never have and we never should walk by on the other side of the road".
He was among 66 Labour MPs who voted with the Government while seven Conservatives opposed the plans for military action.
Mr Cameron said: "I believe the House has taken the right decision to keep the UK safe - military action in Syria as one part of a broader strategy."
Foreign Secretary Philip Hammond said Britain was "safer" following the decision to back air strikes.
"We are very pleased that a significant number of Labour MPs have voted with the Government tonight so we have got a clear majority across the House of Commons in support of the action that we are now going to be taking to degrade this evil terrorist organisation, " he told Sky News.
"Britain is safer tonight because of the decision that the House of Commons has taken."
The vote has blown open deep divisions in the Labour Party with claims that MPs in favour of military action have faced threats of recriminations.
Leader Jeremy Corbyn's protests that the Government had failed to set out a convincing case did little to persuade a significant number of his parliamentary party, with 11 members of the shadow cabinet - including shadow foreign secretary Hilary Benn, deputy leader Tom Watson, shadow education secretary Lucy Powell, shadow health secretary Heidi Alexander and shadow Commons leader Chris Bryant - choosing to support Mr Cameron.
Pacifist Mr Corbyn was forced to offer his MPs a free vote and allowed Mr Benn to wrap up the debate arguing in favour of air strikes, in a messy compromise to stop the party from falling apart.
In astonishing scenes, the shadow foreign secretary gave an impassioned speech directly challenging his party leader, who sat beside him watching while MPs from across the House broke out into cheers of support.
Mr Benn told MPs Britain was under threat from fascists that held the country in contempt.
He added: "I say the threat is now and there are rarely, if ever, perfect circumstances in which to deploy military forces."
Mr Cameron opened more than 10 hours of debate in the Commons by warning that the "women-raping, Muslim-murdering, medieval monsters" of IS were "plotting to kill us and to radicalise our children right now".
Critics of the military intervention have disputed claims that 70,000 moderate fighters in Syria would be able to take on IS.
Tory chairman of the defence select committee Julian Lewis warned that "instead of having dodgy dossiers, we now have bogus battalions of moderate fighters".
US president Barack Obama welcomed the vote, describing IS as "a global threat that must be defeated by a global response".
The US-based SITE Intelligence Group, which monitors jihadist threats, said "Islamic State (IS) supporters on Twitter erupted in threats toward the UK and other Western countries" following the vote.
Statement from UUP MPs
Ulster Unionist MPs, Tom Elliott and Danny Kinahan, have issued a joint statement following Wednesday night's vote in the House of Commons.
"The vote has been taken and we must all coalesce around the will of Parliament.
"A wide-ranging strategy has been decided on, which includes air strikes against Daesh in Syria. We have a collective duty to unite behind our brave service men and women who will be flying sorties over Syria, potentially within hours.
"Commanding our men and women to intervene where they could potentially be killed or injured is one of the gravest decisions that Parliament can take. Our thoughts and prayers are with them and all our Armed Forces.
"We ask everyone to remember we did not seek this fight, but we cannot walk away from taking a stand against the slaughter of the innocent that is the tactic of those who attack us and despise our way of life."
The Prime Minister was asked 14 times to apologise for his "terrorist sympathiser" comment throughout the debate.
Labour leader Jeremy Corbyn, put the PM on the spot by saying that those with different views must be "treated with respect".
He says the Prime Minister's attempt to brand people not supporting his view as 'terrorist sympathisers', "demeans the office of Prime Minister and I believe undermines the seriousness of deliberations today."
He also called for the PM to apologise by saying: "If the Prime Minister wants to apologise I would be happy to hear from him."
Corbyn told MPs: "It is impossible to avoid the conclusion that the prime minister understands public opposition to his ill thought-out rush to war is growing - and wants to hold the vote before it slips from his hands.
"It's become increasingly clear that the prime minister's proposals for military action simply do not stack up."
He disputed Cameron's claim about ground troops, saying it was "quite clear there are no such forces" and only extremists would take advantage of the strikes against Isil.
Margaret Beckett, Labour's former foreign secretary: We must help France
Margaret Beckett argued in support of air strikes in Syria, saying that Isil can be judged not by their words, but by their "deeds" and action must be taken to stop them.
She said Britain has a duty to help France and posed the question: "How would we feel if France refused to help us in the reverse situation?"
UK has an important role to play in global fight against Daesh – Danny Kinahan MP
South Antrim MP Danny Kinahan has said the United Kingdom has an important role to play in the global fight against Daesh in Syria.
He said: “This is not a decision to be made lightly. Having recently visited Kurdistan, witnessing the efforts on the ground to fight Daesh and hearing the extensive proposals of the UK Government, I am certain that doing nothing is not an option.
“Having read the motion, I believe that there is a framework in line with the United Nations Charter. This is not a vote to go to war; nor is it a vote to bomb Syria. The vote today is to decide on a coordinated operation to tackle Daesh in Syria, as our forces are currently successfully doing in Iraq.
"Air strikes would form part of a wider campaign, which will include humanitarian support and planning for post-conflict stabilisation in Syria. Political and diplomatic efforts must be paired with military action, and I feel assured that extensive humanitarian work within the region will be paramount in any short or long term plan.
"The United Kingdom is a top tier target for Daesh. It is important that we are part of the coalition effort to bring an end to their indiscriminate terror. If you are stung by a wasp, you must remove the nest.”
DUP and Ulster Unionist Party to support vote
The majority of Northern Ireland's MPs will support air strikes in Syria during Wednesday's vote.
The Democratic Unionist Party (DUP) deputy leader, Nigel Dodds, said the party's eight MPs will support the Government and has warned against "the consequences of appeasing and indulging terrorism".
Along with the eight MPs of the DUP supporting Wednesday's vote, two MPs from the Ulster Unionist Party will back the intervention.
Tom Elliott MP of the UUP said: “The Ulster Unionist Party has indicated for some time that if the conditions set out by the Prime Minister on military intervention in Syria were reasonable that our MPs would support the action.
“We have now seen the motion and believe that it is a framework in line with the United Nations Charter and United Nations Security Council Resolution 2249.
“While we will monitor today’s debate and assess what is said by the Prime Minister and other Government representatives, it is the intention that the Ulster Unionist Party Members of Parliament will be voting in favour of the motion. The Party believes it meets the criteria we had outlined as necessary to support military action."
Social Democratic and Labour Party to oppose
The Social Democratic and Labour Party MPs will vote against air strikes in Syria.
The leader of the SDLP, Colum Eastwood, said his party's three MPs "will proudly walk through the voting lobbies with our colleagues in Labour, the Scottish National Party, Plaid Cymru and other parties to oppose military action".
MPs will vote on war in Syria after more than 10 hours of debate throughout the day.
SDLP leader Colum Eastwood asks for Mr Cameron to withdraw remarks against the opposition
Mr Eastwood also called on David Cameron to withdraw remarks describing MPs opposed to air strikes in Syria as 'terrorist sympathisers'.
On Tuesday David Cameron told Conservative MPs not to side with "a bunch of terrorist sympathisers" ahead of the vote on UK air strikes.
“You should not be walking through the lobbies with Jeremy Corbyn and a bunch of terrorist sympathisers,” the PM reportedly told a meeting of the 1922 committee.
Mr Eastwood said: "David Cameron’s remarks describing those opposed to air strikes in Syria as ‘terrorist sympathisers’ are appalling, inaccurate and offensive in the extreme.
"Opposing military action in Syria that will kill innocents and can only feed the evil we all want to defeat is not sympathy with terrorists, it’s part of the lesson we have learned from decades of conflict.
"To describe people like Mark Durkan, Margaret Ritchie and Alasdair McDonnell as ‘terrorist sympathisers’ is absolutely galling. These are people who stood strongly against violence for over forty years at great personal risk while people like David Cameron enjoyed a life of privilege. His comments are totally despicable and he should withdraw them immediately.
"SDLP MPs will proudly walk through the voting lobbies with our colleagues in Labour, the SNP, Plaid Cymru and other parties to oppose military action tomorrow. We will not legitimise the trigger finger of a Prime Minister more concerned with the theatrics of winning a political victory over the Labour Party than the devastation that will rain down on innocents in Raqqa as they are used as human shields by vicious cowards in IS.
"There are all sorts of claims that airstrikes are a precise form of attack. Yet we know from experience in places like Gaza that they’re not. I’ve been at the scene of an airstrike the day after someone pressed the button. I know the devastation they can have. This is not the right way to deal with the threat from IS."
"Cameron will win no allies by decrying those with legitimate concerns about his plans. He should resile from his comments immediately and see sense."
Labour dismissed the Prime Minister’s comments as a "contemptible and desperate slur which demeans his office".
A Labour party spokesman said: "He clearly realises he has failed to make a convincing case for military action in Syria and opinion is shifting away from him."
Earlier DUP Deputy leader Nigel Dodds MP said that the DUP would be supporting the Government’s motion on UK military action in Syria.
Mr Dodds said: "Our test throughout has been one of realism. Our experience in Northern Ireland has taught us that no other approach can be brought to terrorism.
"We needed to know that the vile terrorists of ISIL/Daesh would be the target. We had to be sure that they are a clear and present danger to the UK. We needed to be convinced that British action would make a real and practical difference. And we required a definite strategic framework being in place, including a clear exit strategy for British personnel.
"After repeated briefings from the National Security Council on Privy Council Terms, and much discussion with the Prime Minister and others in government, we have concluded that the time is right for us to act, and to act decisively.
"Terrorism requires an answer from all civilised countries. We in Northern Ireland know what it’s like for terrorism to be ignored or appeased.
"Unlike the failed strategy advocated in 2013, which we opposed, there is now a realistic chance that overwhelming pressure can be brought to bear against Daesh.
"The Vienna agreement, the range of countries, now including Germany, ready to act militarily, and the unanimous support in the UN Security Council all point to the differences with 2013.
"Paris, like the downing of the Russian Metrojet in Sinai and the recent bomb attacks in Beirut, were assaults upon civilised values which must be met with resolve and quiet certainty. No other British City should have to suffer the way Belfast and other towns and places in Northern Ireland did for so many years. If we can realistically do something to destroy this evil, to prevent it spreading still further, we should act now.
"I applaud the specific commitments the Prime Minister has made in response to the points I have put to him, not least about the use of British ground forces. Western arms can do their bit to help address Middle Eastern problems, but ultimately they must solve their problems themselves.
"But the moment has come where we can no longer stand by on the other side. Civilians are dying, being raped or enslaved at the hands of ISIL/Daesh every day. These are the civilian casualties already happening and we must not through inaction prolong their suffering.
"Now that British armed forces are to be employed in the common good, it is the duty of every credible political figure to offer them his or her support. The Leader of the Opposition has a reprehensible track record of defending the claims of terrorists against our brave servicemen and women. He will not easily be forgiven if he does so again. We wish HM Armed Forces success as they do their hard and necessary work, and pray for a safe return for them all."