The couple took to Instagram on Tuesday with a picture of Stefani sporting a new ring, with the caption "@blakeshelton yes please!" I love you.
The two coaches on "The Voice" met on the set of the singing show in 2015, and their friendship soon turned into a partnership.
Shelton's track "Turnin' Me On" is about Stefani, and Stefani's 2016 song, "Make Me Love You" is about Shelton.
Stefani shares three children, Kingston, Zuma and Apollo with her ex-husband Gavin Rossdale.