The EDA's role is to attract businesses to the state and keep them here.
The agency said it was also splitting up Franzini's role, creating a new position of president and chief operating officer at a salary of $205,000.
Before joining the authority, Franzini was an assistant treasurer with the New Jersey Department of the Treasury. She holds an M.B.A. degree in finance and public management from the Wharton School of the University of Pennsylvania.
Brown is Christie's appointments counsel, a job that involves assisting with high-level appointees.
She resigned as second-in-command of the U.S. Attorney's Office in Newark in 2009 amid headlines over the mortgage loan she accepted from Christie in 2007.
Christie did not disclose the loan on mandatory ethics forms or initially report it on his federal income taxes. He said at the time that he and his wife made the loan to Brown, a family friend, after her husband lost his job.
Brown, a graduate of Drew University and the Georgetown University Law Center, was responsible for the management and operation of a 300-employee office when she worked as a federal prosecutor specializing in white-collar crime, the EDA said.
She will be responsible for providing oversight of the EDA's "strategic direction, sound ethical and governance processes," the authority said.
The board named the EDA's senior vice president of finance and development, Timothy Lizura, to the new post of chief operating officer and president.
He will oversee management of the EDA's incentive and financing program portfolio and real estate development. He'll also handle the authority's financial and accounting matters.