"He looked good," Harrison told reporters. "He's working his tail off in every aspect out here."
Less than halfway through a five-year, $125 million contract, Hamilton was traded to the Rangers by the Angels on Monday after two troubled seasons filled with poor performance, injuries and substance-abuse relapse.
Hamilton, who is on the 15-day disabled list while recovering from right-shoulder surgery Feb. 4, is working out in Arizona before beginning an injury rehabilitation assignment with Triple-A Round Rock.
He is on track to be activated during the second half of May.
Information from The Associated Press was used in this report.