The 26-year-old singer shared the news on Twitter. Gilbert proposed to her on Christmas, said The Hollywood Reporter.
She posted a photoshopped snap of the happy couple as they might look on their wedding day, along with caption, "Hey guess what?"
Gilbert posted about the engagement on his Instagram account. "Popped the question on Christmas Day!" he wrote.
Messages of congratulations soon flowed in from the singing community. Katy Perry and Taylor Swift were among the first to send their best wishes.