Alfredo Cardoso, a photojournalist from the violent, southwestern state of Guerrero, was gunned down after being abducted from his home on Friday, local media reported.
The Guerrero attorney general's office said in a statement Cardoso had succumbed to his injuries in hospital.
It was not immediately clear if the killing of Cardoso was linked to his work in Mexico, which is one of the most deadly countries for journalists worldwide.
On Thursday, Fredy Lopez, a radio broadcaster in the southern state of Chiapas, was shot dead.
During the first three years of the administration of President Andres Manuel Lopez Obrador at least 23 journalists had been murdered before Cardoso, according to a tally kept by freedom of expression advocacy group Article 19