Walker (6-7, 220), a native of Chicago's south suburbs, considered Northwestern and a number of other schools for a potential transfer.
NCAA rules allow Walker to play with Xavier immediately this season due to the fact that he has already graduated from Vanderbilt and will study a program not available at his previous school.
As a junior, Walker averaged just three points per game while battling injuries and illness. In high school, he was ranked as a three-star prospect by Scout.com.
Walker would've been the Wildcats' second transfer added this offseason. In May, TCU transfer Nikola Cerina was added to the roster. Unlike Walker, Cerina will have to sit out the 2011-2012 season.