The 23-year-old starter 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."
The Reds issued a statement saying, "We do not condone behavior of the type alleged, which is wholly inconsistent with the principles of this organization and our community and is detrimental to the positive direction we seek to follow. When the legal process has been completed, we will handle this matter internally."
Police arrest reports said Leake removed the price tags from six American Rag T-shirts at a Macy's store and tried to leave without paying for them. Leake makes $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 was the 21st player who went right from the draft to the majors since 1965.
The right-hander helped the Reds get started toward their NL Central title, going 8-4 with a 4.23 ERA in 22 starts and two relief appearances. The Reds shut him down at 138 1-3 innings, not wanting to hurt his arm by pushing him too far as a rookie.
The Reds have been relying on Leake again this season while they get through shoulder injuries to starters Johnny Cueto and Homer Bailey, who are on rehab stints in the minors and could return by the end of the month. Leake has made three starts, going 2-0 with a 5.40 ERA.