The 36-year-old fighter, who was a professional matador for 12 years, died in the French town of Mont-de-Marsan, near the Spanish border.
Fandino's feet became tangled in the cape used to goad the specially trained fighting bull and he was left with horrific injuries after the animal plunged its horn into his lung.
The matador, who had a wife and a daughter, came from Spain's Basque region and fought hundreds of bulls during his career in the controversial bloodsport.
It is understood his heart stopped in the ambulance and on his arrival at hospital, doctors could not do anything to save his life.
Horrific photos show Fandino being tossed into the air by the enraged animal, which also suffered brutal wounds in the ring.
"It's a tragedy," said a shocked colleague. "We just do not know how it could have happened."
Tributes are flooding in on social networking sites, with rancher Victorino Martin tweeting: "Our friend and great bullfighter Ivan Fandino dies in France. A great loss for the world of bullfighting. We are dismayed."
Shocked spectators watched the matador land on the floor before the bull plunged its horn into his chest.
Two other matadors, Juan del Alamo and Thomas Dufau, were due to take to the ring later in the afternoon.
The last Spanish bullfighter who died due to a goring was Victor Barrio, who was killed at the age of 29 after being savaged in the bullring in Teruel on July 9, 2016.
He was the first Spanish matador to die in the arena since 1992.
Spanish-style bullfights enjoy legal protections in the parts of southern France where the so-called sport is practised.
Around 1,000 bulls a year are killed in this way in France every year.
The country has four bullfighting schools and the practice is designated as an "uninterrupted local tradition" in the limited areas where fights are held.
Humane Society International said in a statement: "The matador's death is a tragedy but for the 1,000 bulls brutally killed in French bullfights every year, every single fight is a tragedy in which they have no chance of escaping a protracted and painful death.
"Bloodsports like this should be consigned to the history books, no-one should lose their life for entertainment, human or animal."