In a statement, McPherson said: "I want to thank the wonderful team of individuals who have worked with me throughout my time here and wish them nothing but the best."
No replacement was named, but the network said one will be announced shortly. Multiple reports suggested that Paul Lee, president of ABC Family channel, was set to take over. Lee joined ABC in 2004; before that he was CEO and founder of BBC America.
During McPherson's tenure, ABC had seen mostly improving years at the network, pushing it up from last place among all network in the key adults 18-49 viewers -- but not quite to the No. 1 spot. He had been responsible for big-rated shows -- "Desperate Housewives," "Grey's Anatomy" and "Lost." In addition, to ABC's prime-time lineup, McPherson oversaw its sister company ABC Studios.
Always outspoken, McPherson had no problem jousting with other network executives, including Ben Silverman, chairman of NBC Entertainment.
The news comes as the nation's TV critics are about to gather at an annual summer event, the Television Critics Association meeting, in Beverly Hills.
Last year, ABC came in third place among all networks in total viewers; it tied with NBC for third place among key adult 18-49 viewers.