Johnson posted a photo of Gretzky's hand with an engagement ring on her finger with the caption "She said yes!!!"
Gretzky, the daughter of hockey legend Wayne Gretzky, retweeted the picture and several congratulatory messages from friends and family.
"Congrats to my sister @PaulinaGretzky and @DJohnsonPGA on the engagement. Love you guys," tweeted Trevor Gretzky, Paulina's younger brother and a prospect in the Chicago Cubs organization.
Johnson is a professional golfer on the PGA Tour.