Smith, who signed with the Arizona Diamondbacks back in June, tweeted a video of his parents learning of the surprise.
He wrote, “Thank you for everything you have done for me! This doesn’t make up for any of it. Love you both so much. Our home is finally all YOURS. Merry Christmas!”
“Thank you for raising me in a great home filled with love,” Smith said in a letter read by his mother. “Because of all the sacrifices you made to get me where I am. I want our family home to be yours.”
Smith’s mother and father could be seen crying toward the end of the video when they realized what their son had given them.
According to ESPN, Smith was picked seventh overall in the amateur baseball draft. He received a $5 million bonus.
After being drafted, Smith played for the Class A Hillsboro Hops. In 42 games, Smith hit .318 with 27 RBIs for the Oregon-based Diamondbacks affiliate, ESPN reported.
An executive with the Diamondbacks retweeted Smith’s video and wrote, “How awesome is this? Our first round pick paid off the mortgage on his parents’ home for Christmas. Also, someone is cutting onions in here.”