Locklin died Sunday at his home in Brewton, Ala., Opry publicist Jessie Schmidt said in a statement that did not list a cause. Schmidt did not immediately return calls for more details.
Locklin helped usher in "the Nashville Sound" that gave country music a more lush feel. He performed on the Grand Ole Opry for more than 40 years.
"I've been blessed to have hit songs that are timeless and appeal to the generations," he said in 2001.
He recently released his 65th album, "By the Grace of God."
His "Send Me the Pillow You Dream On" was a hit in 1958 and "Please Help Me I'm Falling" in 1960.
"Send Me the Pillow You Dream On," which Locklin wrote, also was recorded later by Johnny Tillotson and Dean Martin.
He joined the Grand Ole Opry cast in 1960 and was still performing as late as 2003.
Locklin spent 19 years recording for RCA Records.
His other hits included "Let Me Be the One," "Geisha Girl," "Why, Baby, Why" and "It's a Little More Like Heaven."
In 2001, he released his first album in two decades, "Generations in Song." Vince Gill and Dolly Parton joined him on the LP.
Locklin, as much as any one else, popularized country music in Ireland where he often toured. In the mid-1960s he recorded the album "Irish Songs Country Style" because of his popularity in Ireland.
"The Lord gave me a good voice and I can still sing," he said in 2001.
Locklin was born in McLellan, Fla., where he picked cotton as a youth.
He learned to play guitar at age 9 while bedridden after being hit by a school bus.
He once said he was paid $2 for one of his first paid performances at a Florida roadhouse. Trouble was, his expenses were $5.
Locklin became a regular performer on radio station WCOA in Pensacola, Fla., and on the "Big D Jamboree" on KRLD in Dallas. In 1949 he joined "The Louisiana Hayride" in Shreveport, La.
In the 1970s he was host of TV shows in Houston and Dallas.