Mejia will serve as the Twins fifth starter to open the season, Mike Berardino of the St. Paul Pioneer Press reports.
Mejia posted a 1.88 ERA and struck out 14 over 14.1 innings this spring, and that proved to be enough for the 23-year-old to beat out Tyler Duffey for a rotation spot. The left-hander made his majors debut in 2016, but it spanned just one appearance, so he's a largely unproven commodity. Mejia sports a fastball that can touch the mid-90s, though his size (6-3, 195) suggests there's potentially room to grow in that area.