The government published the offers of up to 1.5 million pesos (USD 83,000) in today's official gazette.
Six journalists have been killed in Mexico so far this year.
The Attorney General's Office did not immediately explain why it included four from this year and one from December.
The government promised changes to protect journalists and pursue their killers following the May 15 murder of prominent journalist Javier Valdez in the western city of Culiacan.
Disclaimer: No Business Standard Journalist was involved in creation of this content