The president's office said that French planes struck targets identified during reconnaissance missions conducted over the past fortnight. French jets have previously carried out air strikes against IS targets in neighbouring Iraq.
"Our country thus confirms its resolute commitment to fight against the terrorist threat represented by Daesh," the French Presidency said, referring to the militant group by another of its acronyms.
"We will strike each time that our national security is at stake," the statement added.
President Francois Hollande announced earlier this month that he was preparing to send jets to Syria. He said at the time that terror attacks had been planned against France from Syria.
A US-led coalition has been carrying out airstrikes against IS in Syria and Iraq for more than a year. France, like the UK, has previously confined its air strikes against the Islamic State group to Iraqi airspace. The UK announced earlier this month it had carried out a drone strike against two British citizens in Syria but has yet to fly manned operations in Syrian airspace.
Analysis: Hugh Scholfield, BBC News, ParisHugh Scholfield, BBC News, Paris wrote an analysis on current events this is some of what he said:
The French air strikes in Syria reflect the shifting emphasis in the war against the Islamic State. Before now, France said that international law prevented it from attacking targets in Syria, and it was adamant that it would do nothing to help - even indirectly - the Assad government. But the situation has changed. France now says it has evidence that IS planned terror attacks against it from Syria - making air strikes against the militants legitimate under UN rules on self-defence.
The biggest change though is that France has swallowed hard and accepted that getting rid of Mr Assad is no longer the priority. Paris will not ever say it too loudly - because it used to be the Syrian president's most outspoken opponent - but today the fight against IS trumps everything else.
The biggest change though is that France has swallowed hard and accepted that getting rid of Mr Assad is no longer the priority. Paris will not ever say it too loudly - because it used to be the Syrian president's most outspoken opponent - but today the fight against IS trumps everything else.
I agree that we should start fighting against IS because all that they are doing is wrong and against humanity, but I fear they might start another un-needed war. Already thousands of innocent Syrians are fleeing the country in terror hoping they can survive. I feel the countries need to come together to battle IS but before that we need to help the refugees that are helpless otherwise we will have two serious problems to deal with, like we have at the moment. If we aren't careful we could end up hurting more people than needed not only Syrians but also from our own countries such as the British and French. If they are going to fight back they need to do so quickly to keep their people safe and to destroy IS.