The influencer, Cesar Gastelum, was killed on Tuesday night in the Sinaloa state capital of Culiacan, officials said.
Mexican authorities implied the killing of the young man was linked to cartel violence but did not blame any particular group.
A video of the moment of his death, which was viewed by The Associated Press, shows him laughing with two other men in the parking lot of a KFC when two men pull up on a motorcycle.
One is seen pulling out a gun and shooting Gastelum. The attackers then flee the scene.
The attack was carried out just blocks away from the local prosecutor's office during rush hour.
Mexico's security cabinet and local prosecutors said an investigation was ongoing, and it appeared Gastelum had released some videos in which he "alluded to a faction of a criminal group".
Mexican President Claudia Sheinbaum told journalists during her morning news conference on Wednesday that the "perpetrators must be arrested".
"We must find out why this deplorable homicide occurred," she said.
Gastelum had more than 650,000 followers on TikTok, and more on Instagram and other social media platforms and would regularly post comedy videos and content layered over Mexican regional music.
Sinaloa has in recent years been ravaged by warring between two factions of the Sinaloa Cartel.
At the height of the fighting, dead bodies would be left across the city marked with a faction's signature.
One of them, Los Chapitos, would regularly leave a pizza or a pizza box on a dead body.
The other, Los Mayos, would leave behind a sombrero, and it soon became dangerous to wear the hats in Culiacan as it could signify allegiance to one group.
On Tuesday night, Gastelum was filmed wearing a white sombrero.
On Wednesday, candles were lit on the pavement where he was killed.
It was the second time in little more than a year that a content creator was fatally shot by gunmen on a livestream.
In May 2025, 23-year-old beauty influencer Valeria Marquez was shot and killed while doing a TikTok livestream at a beauty salon in the central Mexican state of Jalisco.
