Véronique Robert, 54, worked for France Télévisions. Her colleague, Stéphane Villeneuve, and Kurdish journalist Bakhtiar Haddad died Tuesday in the same incident.
"Too many headstones at the cemetery of the great reporters," Christophe Deloire, secretary general of Reporters Without Borders, said in a tweet.
The journalists were with Iraqi army forces in an ISIS-held area of the Ras Al-Jadah district of Mosul when the blast occurred. They were on assignment in Mosul for the France 2 TV channel's current affairs program "Envoyé Spécial," the monitoring group Reporters Without Borders said.
A fourth journalist -- Samuel Forey -- was injured as well.
Iraqi forces are in the final stages of ousting ISIS from Mosul, the country's second largest city.
Robert had undergone an operation in Baghdad earlier this week and was flown overnight Thursday to a hospital near Paris, France Télévisions said.
The French Ministry of Foreign Affairs issued condolences on Saturday to Robert's family and the network.
Desperation in Mosul
As ISIS has been squeezed to just a handful of Mosul neighborhoods, including the Old City, the civilians held hostage there are running out of food. ISIS fighters have massacred people, young and old, who tried to flee, residents have said.
The fighting has caused the displacement of more than 700,000 people since the offensive began, and the United Nations migration agency has warned in recent weeks that the number of people fleeing the city has soared.
ISIS this week blew up a historic mosque in Mosul that was the ideological heart of the terror group and the birthplace of its self-declared caliphate, the United States and Iraq have said. The Great Mosque of al-Nuri, with its leaning minaret, was in the Old City.