Stefani videotaped an Instagram video originally posted by user @Makegirlz, which shows a nail artist impressively painting a portrait of Shelton as the country crooner's song "Lonely Tonight" plays in the background. Towards the end of the brief video, you can hear Stefani giggling.
"Congrats @blakeshelton," the No Doubt frontwoman wrote, using the hashtags "#cmtartistoftheyear #michaeljacksonofcountrymusic."
At the awards show, Shelton -- who divorced from fellow country singer Miranda Lambert in July -- referenced his rollercoaster ride of a year in his acceptance speech.
"I want to thank my entire team," the 39-year-old said onstage. "There's too many people to stand up here and name, but more importantly this has been a crazy year from the way it started to the way it's ending so awesome for me, so thank y'all. This is a great way to end it for me. Thank you so much."
Earlier this week, ET caught up with Shelton before Stefani's emotional performance of her newest hit, "Used to Love You," on The Voice. He couldn't help but gush over his new relationship with the edgy rocker.