He'd been diagnosed with lung cancer.
Grand Ole Opry VP Pete Fisher said the Opry family "is deeply saddened" by the passing of "our dear friend."
His illness came after a comeback that saw him recording again and gaining new fans even as he reached his 80s.
In May, he celebrated his 50th year in the Opry and signed his first record contract in years. His new CD "Wagonmaster" earned some of his best reviews. Over the summer he opened for the rock duo White Stripes at a sold-out concert at New York's Madison Square Garden where he was touched by the reaction of the young audience.
His many hits included "Green Green Grass of Home," but he is perhaps best known for hiring 21-year-old Dolly Parton in 1967 to be his duet partner.
Porter Wagoner was 80.