The network says Stelter will also serve as a senior media correspondent for CNN Worldwide.
He comes from The New York Times, where he was a media industry reporter. He replaces Howard Kurtz, who left the two-decade-old program earlier this year to join Fox News Channel.
Stelter joined The New York Times in 2007. Before that, he created TVNewser, a blog covering the TV news industry.
He is the author of "Top of the Morning: Inside the Cutthroat World of Morning TV," about the competitive world of morning news shows.
"Reliable Sources" airs Sundays at 11 a.m. Eastern time.