The 47-year-old singer and 41-year-old country star collaborated on the song "You Make It Feel Like Christmas" for Stefani's upcoming holiday album of the same name.
"#ChristmasCameEarly preorder & stream #YouMakeItFeelLikeChristmas @blakeshelton now," the singer announced on Twitter.
You Make It Feel Like Christmas includes 11 other songs, including Stefani's renditions of "Jingle Bells," "Let It Snow" and "Santa Baby." The album is scheduled for release Friday, Oct. 6.
Stefani and Shelton previously collaborated on the song "Go Ahead and Break My Heart," which appeared on Shelton's 10th studio album, If I'm Honest. Shelton discussed the duet in an interview with People in April 2016.
"We were at a point where it's like, 'Do we want to go there? What will people think?'" the country star told the magazine. "And then we finally just got to the point where it's like, 'You know what? I don't give a [expletive]."
"I love this song!" he said. "This song's important to us and the fact that we wrote it together is so important to both of us."
Stefani and Shelton confirmed their relationship in November 2015 following their splits from their respective spouses, Gavin Rossdale and Miranda Lambert. Rossdale and Lambert have since started dating Sophia Thomalla and Anderson East.