Suero was Washington's most used reliever during the 2019 season; he led the team in games pitched and relief innings. He recorded his first Major League save on June 21, 2019 at Nationals Park. Suero was left off Washington's roster to start the 2019 National League Championship Series, placed on the roster when Daniel Hudson went on paternity leave and then removed again when Hudson returned. Suero appeared in the 2019 World Series in three different games and retired all five batters he faced. He was the only pitcher to appear in the series and not allow any baserunners.