"I can't wait to make you my wife," Chmerkovskiy captioned the photo, which shows him on one knee in a suit as Johnson expresses serious shock in a silver mini.
"I knew the moment I met you, you were the man of my dreams and I wanted to be with you forever," she added on her own page. "Thank you for making my fairytale come true today! Cannot believe I get to call you my FIANCÉ!!!! #engaged"
The two first started dating in February 2016, but split. They rekindled their romance in 2017 and have had engagement on the mind since.
"I should def put a ring on it," he wrote on Twitter in May, while retweeting a GIF of Johnson looking all kinds of gorgeous in a red dress. She also said "Time's a-ticking" around the same time when asked about possibly tying the knot.