The 33-year-old pitched four innings in the controlled affair, with some innings going to four outs in order to elevate his pitch count. He allowed four hits and two runs with no walks and three strikeouts.
"I felt good overall today and had a better feel of my command, being able to locate where I wanted to," Iwakuma said through interpreter Antony Suzuki. "I was able to work from my stretch with runners on, and that was good to get that feel back.
"I felt like my arm speed and arm action was better than my first outing, so I am satisfied with where I am at being the second game in camp."
Iwakuma, who won 15 games last year for Seattle, threw two perfect innings in his Cactus League debut last Saturday against the D-backs as he prepares for his fourth season in the Majors with the Mariners.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.