Photo: BFMTV screengrab
Three security guards carried the woman from the Femen group, who had the same slogan daubed on her chest and back, out of the Paris venue.
Femen activists also disrupted a speech by Le Pen in May 2015.
Le Pen, the only woman standing in France's presidential election, has styled herself as a feminist.
Femen said on Facebook that “nothing in Marine Le Pen's programme promotes the emancipation of women. No proposal is made to further the equality of the sexes.”
Le Pen's refusal to wear a headscarf to meet Lebanon's top Sunni Muslim cleric on Tuesday during a visit to Lebanon was no more than a “media stunt”, Femen said.
The 48-year-old head of the anti-EU, anti-immigrant National Front (FN) party, is tipped to win the first round of the two-stage presidential polls on April 23, scoring 25-27.5 percent in the latest voter surveys.
While she is currently forecast to lose in the second round on May 7, she appears to be closing the gap.
And she can count American white supremacist David Duke among her fans, after he took to Twitter on Wednesday to extoll her political prowess and controversial father.
“Her father is a great man, a true patriot. He raised a strong & intelligent woman who understands how to play 21st century politics,” Duke said on Twitter, responding to a question about his views on Le Pen.