Owens died at a Bakersfield hospice hospital Monday after a long battle with Alzheimer's disease, said family spokesman Jim Shaw, who played keyboards in Buck Owens' band, the Buckaroos.
Her death came weeks after Buck Owens died on March 25.
Born Bonnie Campbell, she met Buck Owens in Mesa, Ariz., in the mid-1940s when she was a teenager and he had a local radio show. When Owens discovered that she could sing, he helped her get a job with him on another radio show in 1947.
They married a year later, had two sons and separated in the early 1950s. They remained friends and she sometimes performed with Owens in the truck-stop town's thriving juke joints.
While working as a waitress at a Bakersfield club, she sang with Fuzzy Owen and his band, the Sun Valley Playboys. It was Owen who suggested that she records a duet with a young Merle Haggard, and their rendition of "Just Between the Two of Us" hit the top of the country charts in 1965 and won the best vocal group award from the Academy of Country Music.
She married Haggard that same year and toured with him and his band, The Strangers, for nearly a decade. They divorced in 1978 and she later married her third husband, Fred McMillan.
Despite recording six solo albums and two duet albums with Haggard she remained modest about her musical contributions.
"I was a follower; Buck and Merle were leaders," she said. "I did what was needed and I did what I could."