According to TMZ, which first reported the news, Shelton filed for divorce "a while ago," and a judge was expected to officially dissolve the marriage on Monday.
"This is not the future we envisioned," their representatives told Us Weekly in a statement. "And it is with heavy hearts that we move forward separately. We are real people, with real lives, with real families, friends and colleagues. Therefore, we kindly ask for privacy and compassion concerning this very personal matter."
TVGuide.com's emails to the couple's reps were not immediately returned on Monday.
Under the couple's prenuptial agreement, Shelton, 39, will keep their ranch in Oklahoma and Lambert, 31, will keep their home in Nashville as well as the animals she kept on the ranch, including horses, a camel and a llama, TMZ reports.
Considered one of country music's power couples, Lambert and Shelton have been plagued by rumors of difficulty in their marriage and infidelity on the part of Shelton. Notably, Lambert did not thank Shelton in any of her acceptance speeches after winning multiple prizes at the ACM Awards back in April, despite the fact that he co-hosted the show with Luke Bryan.
Shelton was previously married to Kaynette Gern from 2003 to 2006, when they divorced. He and Lambert met in 2005, began dating in 2006, and were married in 2011. This was the first marriage for Lambert.