Blake Shelton was definitely not expecting this.

On the country crooner's 45th birthday, his fiancée, Gwen Stefani, threw him a backyard surprise party and proudly documented it on her social media.

In a video posted to Stefani's Instagram feed, Shelton is caught completely off guard walking through an open sliding door into a backyard full of people yelling, "Surprise!"

"The Voice" judge even moved out of the way, assuming the "surprise" was meant for someone else.

"It's your birthday," Stefani can be heard telling him before gently pushing him through the doors and onto the deck as the crowd of loved ones laughed in the background.

"celebrating my besties b day today love u @blakeshelton," Stefani captioned the post, adding the hashtag "#favoritecountrysinger.

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Video from Stefani's social media shows the average sized backyard full of the couple's friends and family. Large balloons that read "Happy Bday Blake" can be seen along the fence, and additional video shows an unidentified person dressed in a Superman costume singing "Happy Birthday" to Shelton.

Stefani shared old photos of Shelton on Instagram for his birthday.Instagram

Stefani shared old photos of Shelton on Instagram for his birthday.Instagram

Shelton's surprise party comes one week after he and Stefani sparked rumors they may have already tied the knot in secret. Photos showed Stefani wearing a diamond-covered wedding band along with her engagement ring while out with Shelton and her 7-year-old son, Apollo, on Saturday, June 13 in Santa Monica.

The bride-to-be was spotted wearing the alleged wedding band just two days after posting a photo on Instagram with the caption, "SHE'S GETTING MARRIIIEEEEED" while holding a present wrapped in white paper.

Shelton proposed to Stefani in October 2020 with a 6 to 9 carat ring – five years after a rep confirmed to Page Six that the two were dating in November 2015.