The news isn't entirely unexpected given that Zander has been under fire for months for missing quarterly targets.
Brown is expected to give Motorola more discipline on the cost side and improve operations. Zander's tenure was marked by a strong start and the launch of the popular Razr phone. However, Motorola ran into trouble amid price competition.
"This is the right time for me to move on to the next phase in my life and spend more time with my family. I am grateful I had the opportunity to lead Motorola over the last four years. It's been a wonderful experience."
Brown joined Motorola in March and has run four different Motorola businesses. He also led the acquisition of Symbol Technologies.
Update: Billionaire Carl Icahn, who has been pushing for Zander's ouster, had the following to say in a statement:
"I believe that the replacement of Ed Zander as CEO is a positive step for Motorola, but that the action of the Board was long past due. As I said at Motorola's shareholder's meeting last year, although I like Ed Zander personally, I never thought that he was the right man for the job at Motorola. Further, I believe that the steps announced today do not even begin to address the major problems at Motorola. In my opinion, Motorola should be split into separate companies: a mobile devices company; an enterprise mobility company; a connected home company; and a company focused on mobile networks infrastructure. In particular, I believe that the best opportunity for the mobile devices' business to attract top flight management and to prosper and grow is to establish it as a stand alone business."