The last permanent CEO, George Samenuk, resigned amid a stock option mess. Fuller will advise DeWalt during the transition, according to a statement.
McAfee's new CEO previously led EMC's Customer Service Operations, overseeing worldwide customer operations. DeWalt was CEO of content management software company Documentum prior to its 2003 EMC acquisition.
As CEO, DeWalt will have to alleviate concerns from Wall Street and federal prosecutors, experts say.
"McAfee seems to have a never-ending string of financial misdeeds coming to light," Gartner analyst John Pescatore told internetnews.com. "Any new CEO will first have to convince Wall Street and shareholders that McAfee is finally beyond that now."
Last week, former McAfee general counsel Kent Roberts pled not guilty to federal fraud charges, including allegedly falsifying an entry in Network Associates' board minutes in 2002 when then-CEO Samenuk received stock options.
Samenuk resigned in October after nearly six years as McAfee CEO, citing "the best interests of the company, shareholders and employees," internetnews.com previously reported.
McAfee non-executive Chairman Chuck Robel echoed Samenuk's words, pointing to DeWalt's "excellent track record in driving shareholder value to McAfee."
McAfee was not immediately available for comment.
By naming DeWalt, McAfee quieted Wall Street concerns that the troubled security company couldn't attract high-caliber candidates, said Cowen and Company financial analyst Walt Pritchard.