Sophie was already in Vegas to support Joe and his brothers at the Billboard Music Awards, where they were among this year’s performers.
Just hours after the awards show ended, the couple quickly headed to a Las Vegas chapel, where they seemingly made things official, in a ceremony officiated by an Elvis Presley impersonator.
And in an even more surprising twist, the whole thing came to people’s attention on Diplo’s Instagram Story, as he shared a stream of the ceremony on his profile...
The country music Dan + Shay also performed an acoustic version of their track Speechless as Sophie walked down the aisle.
Although the pair are yet to confirm they’re officially married, Entertainment Tonight has reported they’ve seen a copy of their marriage licence, which was obtained earlier that day.
HuffPost UK has contacted representatives for both Sophie and Joe for further comment.
Sophie and Joe confirmed they were engaged in matching Instagram posts in October 2017, after a year of dating.
So far, it’s been a big year for Sophie, who is currently playing Sansa Stark in the final series of Game Of Thrones, and continues to make headlines off-screen because of her social media commentary about the show.
Similarly, Joe reunited with his brothers Kevin and Nick Jonas earlier this year, with their first single in six years, Sucker, debuting in March, and quickly topping the singles chart in the US.
Joe is the last of the Jonas Brothers to get married, with Nick’s lavish wedding to actress Priyanka Chopra getting everyone talking last year.
Kevin Jonas has been married to his wife Danielle Deleasa, with whom he had a short-lived reality series on E!, for just under 10 years.