Lawyer Rodolphe Bosselut, representing Le Pen in the case, confirmed the charges but wouldn't comment.
Le Pen's December 2015 tweets showed executions by IS extremists, including the killing of American reporter James Foley.
The other images showed a tank running over a man in an orange jumpsuit, while another jumpsuit-clad man was shown in a cage being burned alive.
The anti-immigration leader lost to centrist candidate Emmanuel Macron in the second round of the French presidential election run-off in May past year.
Ms. Le Pen was indicted Thursday by a judge in Nanterre and could potentially face a penalty of up to three years in prison or a fine of up to 75,000 euros, L'Express reports.
The move comes after the national assembly voted in November previous year to strip Le Pen of her parliamentary immunity over the three photos posted in 2015.More news: How to Preorder the Galaxy S9 (and 5 Other Great Tech Deals)
Calling the investigation "political interference", Le Pen told a French TV channel, "If they are trying to silence me, they will not succeed".
Ms Le Pen later deleted the picture of Mr Foley after a request from his family, saying she had been unaware of his identity.
The charge against the far right-wing leader was filed on Thursday near Paris.
Le Pen is even considering rebranding the party founded by her father, Jean-Marie Le Pen 45 years ago, with a new name.
She has been placed under formal investigation - a stage in the French legal process equivalent to being charged in Britain - for "distributing violent images", which is an offence in France.
The far-right politician is also under investigation for misuse of EU funds while she was a member of the European Parliament.
The U.S. First Amendment protects Trump from the sort of investigation Le Pen is facing.