Seattle Mariners On June 6, 2011, Hultzen was the second player selected in the
2011 Major League Baseball draft, taken by the
Seattle Mariners. Hultzen signed a contract with Seattle on August 15. The deal was worth a minimum of $8.5 million over five-years, with a $6.35 million signing bonus. He made his professional debut in 2012 with the
Jackson Generals and was promoted to the
Tacoma Rainiers in June. In 25 total starts between the two clubs, he was 9–7 with a 3.05 ERA. He was named to appear in the 2012
All-Star Futures Game. Hultzen missed the majority of the 2013 season due to a shoulder injury. After the 2013 season, he underwent surgery to repair a torn
labrum and
rotator cuff in his shoulder, and missed the entire 2014 season. He played in only three games in 2015 due to injury. In 2016, while rehabbing with the
AZL Mariners, he suffered recurring problems and underwent another surgery. Hultzen elected free agency following the season on November 7, 2016. Hultzen sat out the 2017 season while finishing his university degree.
Chicago Cubs On March 1, 2018, Hultzen signed a minor league contract with the
Chicago Cubs organization. He was assigned to the Triple–A
Iowa Cubs to start the 2019 season. Hultzen allowed zero runs in his major league debut on September 8, 2019. He pitched the seventh inning for the Cubs against the
Milwaukee Brewers. After issuing a hit batsman and a single, he struck out the side. On December 2, Hultzen was non-tendered by Chicago and became a free agent. On January 22, 2020, Hultzen re-signed with the Cubs on a minor league deal. Hultzen did not play in a game in 2020 due to the cancellation of the minor league season because of the
COVID-19 pandemic. He became a free agent on November 2. ==Coaching career==