Ernesto was a famous singer and musician who dazzled audiences with his good looks and his charm. Ernesto was a source of Mexican pride due to his handsome looks, strong morals and his standing up for his fellow Mexicans. He was also thought to be Miguel's great-great-grandfather as well. After his sudden death from being crushed by a giant bell during a performance, he resides as a soul in the Land of the Dead. It is later revealed that Hector had written the songs that Ernesto performs in the film; however, Hector was feeling homesick and had an argument with Ernesto. Ernesto subsequently poisoned Hector and stole the credit for the songs he had written. To preserve his reputation, he orders his personal guards to eject Miguel and Héctor and seizes the latter's family photograph for himself.
When Miguel, Héctor, and Imelda infiltrate Ernesto's Sunrise Spectacular concert to retrieve the photo, Ernesto unintentionally reveals the truth to his whole audience, who turn against him and begin to boo and jeer. In the ensuing altercation, Ernesto is flung by Pepita into a bell tower; the bell comes loose and crushes him in a manner parallel to his real-life death. One year after Miguel returns to the Land of the Living, Héctor is now credited by Santa Cecilia as an authentic musician and songwriter, while Ernesto’s mausoleum is defaced and abandoned, with a sign reading "FORGET YOU" hung on his bust.
- In a deleted scene, Ernesto tries to stop Miguel from exiting the bridge after the countdown, but Ernesto ultimately disintegrates allowing Miguel to escape in the nick of time as the bridge completely dissolves into clusters of flower petals.
- Ernesto was born in 1896 and died in 1942, implying that he was 46 years old.
- Unlike most Pixar villains who die, Ernesto, like many characters in Coco, is already deceased at the beginning of the film and resides in the Land of the Dead.