Flexen signed a minor-league contract with the Rockies on Thursday, Thomas Harding of MLB.com reports.
Flexen has posted a 7.71 ERA over 17 appearances (four starts) at the major-league level this season but was a solid arm for the Mariners from 2021-22 while bouncing between the rotation and bullpen. He will report to Triple-A Albuquerque for now but is a good bet to join the Rockies' rotation sooner rather than later.