Staumont was added to the 40-man roster Tuesday, Jeffrey Flanagan of MLB.com reports.
The Royals have selected Staumont's contract in an effort to protect him from the Rule 5 draft. He's yet to make his big-league debut but reached Triple-A Omaha in each of the last two seasons and posted a 3.51 ERA along with a 1.50 WHIP and 103 strikeouts over 74 innings in 2018.