SCEI president and group CEO Kazuo Hirai will take over Harrison's duties in addition to his own.
Harrison joined Sony in 1992, serving in a variety of executive roles during the company's early PlayStation period. Appointed to the newly-christened position of Worldwide Studios president in 2005, Harrison was responsible for developing a global strategy for Sony's game division, fulfilling a wide range of duties.
Harrison recently criticized Sony Japan for its lack of foresight in regards to the social gaming phenomenon.
"It's a very interesting and frustrating thing for me to experience because I have been banging the drum about social gaming for a long time, with SingStar, EyeToy and Buzz," said Harrison to GamesIndustry.biz last week.
"And our Japanese colleagues said that there is no such thing as social gaming in Japan--people do not play games on the same sofa together in each other's homes. It will never happen. And then out comes the Wii."