Darnell enters his first season with the Somerset Patriots and first in the Atlantic League.
The southpaw made his Major League debut with the Minnesota Twins on May 6, 2014, where he limited the Cleveland Indians to three scoreless innings without and hit and one strikeout.
Overall, Darnell made seven appearances (four starts) with the Twins in 2014 and struck out 22 batters over 24 innings of work.
The Greenbrier, Tennessee resident has spent each of the past two seasons (and a majority of 2014) in the Twins organization with Triple-A Rochester. Last year, Darnell went 8-8 with a 3.53 ERA over 18 starts as a teammate of 2015 Somerset Patriots reliever Buddy Boshers.
The previous season, he went 5-1 with a 2.78 ERA over 35 appearances (seven starts). In 2014, prior to being called up by the Twins, Darnell impressed with a 3.60 ERA and 90 strikeouts in 115 innings of work at Rochester.
The 2010 sixth-round pick from the University of Kentucky owns a 54-46 record with a 3.81 ERA over his seven-year minor league career.