Le Pen is currently under investigation for posting the material in 2015 but the probe is not expected to finish before France’s presidential election, which begins in April.
In France, one can face up to three years in prison and receive a €75,000 ($79,000) fine if convicted on charges of spreading violent images.
A total of 563 MEPs voted in favor of lifting Le Pen's immunity; 48 voted against.
In 2015, Le Pen shared three photos of Daesh executions on her social media account as a response to a journalist who had compared the terror group with her National Front party.
After negative reactions, Le Pen deleted a graphic photo of the death of U.S. journalist James Foley but refused to delete the two remaining images.
Later, a French prosecutor opened an investigation into Le Pen, requesting the revocation of her parliamentary immunity.