The couple, who have been in a relationship since 2016, shared the news on Instagram with the same photograph of a big diamond ring on the "Game of Thrones" star's hand.
While the DNCE frontman, 28, wrote, "She said yes", Turner, 21, shared the picture with the caption, "I said yes".
Jonas's brother Nick, who was a part of their pop band The Jonas Brothers, took to Twitter to congratulate his brother.
"Ahh! Congratulations to my brother... and sister in law to be on your engagement. I love you both so much," he wrote.
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