"My wife's greatest dream came true today," Rory Feek wrote. "She is in heaven."
Rory Feek said his wife died about 2:30 p.m. with her family around her in a home in Indiana.
Martin Feek and her husband were discovered in 2008 after they competed on CMT's music competition show "Can You Duet." Their first single, "Cheater, Cheater," had a popular video with a cameo by Naomi Judd, a judge on "Can You Duet."
Fans fell in love thanks to their talent and to an audition video that showed the couple's devotion to each other. In it, they shared the story of their meeting at a songwriting event in 2002 and the restaurant, Mary Jo's, that Martin Feek opened with her sister-in-law near their home in Columbia, Tennessee.
In 2009, the Feeks won top new vocal duo at the Academy of Country Music Awards. They were nominated for a Grammy Award this year for "If I Needed You."
The couple and their restaurant were also featured in Overstock.com commercials, bringing further exposure. Joey + Rory went on to release six studio albums.
The couple shared Martin Feek's diagnosis of cancer in 2014, soon after the birth of their daughter, Indiana, who has Down syndrome.
Despite intensive treatment and surgery, the cancer spread to her colon, and in November, the devout couple asked fans to pray for her healing and "God's will." The next day, Feek posted that his wife's tumors had continued to grow and said doctors told them that "we need to concentrate now on helping her be comfortable."
"Not the answer we hoped for," he wrote on their blog. "But the answer He has given us."
On Friday he wrote
that, as his wife wished, he would return to Nashville. Saying goodbye was hard, he wrote, but her memories would stay with him and their children.
"It's hard for me to imagine being there without Joey," he wrote. "It's where she will be. ... She's gonna be in the mint growing beside our back deck, the sweet-corn frozen in our freezer and a million other places that her hand and heart has touched around our little farmhouse and community. Joey will still be with us. Everywhere."
Country singer Chris Young expressed his condolences on Twitter. "Have played shows with Joey and Rory before and it's so sad to lose her amazing voice," he wrote.
In addition to her husband and daughter, Martin Feek is survived by her husband's two daughters from an earlier relationship, her parents and three sisters.