Leake, 23, was booked at the Hamilton County Justice Center on a first-degree misdemeanor charge of shoplifting. It carries a maximum of 180 days in jail.
He was arrested about two hours before Cincinnati pitchers were expected at Great American Ball Park to take batting practice before the final game of a series against Pittsburgh. Leake started and got the victory in an 11-2 win over the Pirates on Saturday.
Leake said in a statement released by the Reds that his attorney told him not to discuss the arrest. Leake apologized to his family, to the club and to fans "for this distraction."
In a statement, the Reds said that "when the legal process has been completed, we will handle this matter internally."
Police arrest reports said Leake removed the price tags from six T-shirts at a Macy's store and tried to leave without paying for them. Leake is paid $425,000 in his second season in the majors.
A Macy's spokesman said the company had no comment beyond what was reported by police.
Leake was the eighth overall pick in the June 2009 draft and made the jump directly from Arizona State to the majors last spring, when he won the fifth starter's spot in the rotation. He finished 8-4 with a 4.23 earned-run average in 22 starts.
Colorado Rockies ace Ubaldo Jimenez comes off the 15-day disabled list Tuesday for the middle game of a three-game series.
Jimenez was put on the disabled list after his first start, in the club's season opener, because of a cut cuticle on his right thumb that prevented him from getting velocity on his fastball and spin on his breaking pitches.
Yankees' Feliciano puts off surgery
New York Yankees left-hander Pedro Feliciano will put off shoulder surgery for at least 11/2 months.
Sidelined since spring training, Feliciano was examined Monday by Dr. James Andrews, who recommended a six-week program of shoulder strengthening.
The Yankees said Feliciano will remain with the team during the rehabilitation process. The team said last week that Feliciano has a torn capsule in his left shoulder.